5 Crop Protection

5.1 Integrated Pest Management Integrated Pest Management (IPM) is a system- Pest Prevention atic decision-making process that supports a balanced approach to managing crop and Pest prevention is the first step in avoiding pest livestock production systems for the effective, problems in your vineyard. The objectives are to economical and environmentally-sound suppres- prevent the plants from becoming susceptible to pest sion of pests (insects, mites, plant diseases, attack, to preserve natural enemies (biological weeds, and problem wildlife). control agents), and to avoid attracting or intro- ducing pests into the vineyard. Best management The elements of IPM include: practices to achieve these objectives include:

1. Planning and managing agricultural production  Selecting a vineyard site that is suitable for the systems to prevent insects, plant diseases and grape varieties to be grown, or select grape weeds from becoming pests varieties suited to the site 2. Identifying pests, their natural enemies and  Optimize plant health to avoid predisposing damage plants to attack and to reduce the impact of pest 3. Monitoring populations of pests and beneficial attack on plant production through proper organisms, pest damage, and environmental irrigation and nutrition programs conditions  Encourage the establishment of natural enemies 4. Making control decisions based on potential through use of compatible pesticides and damage, cost of control methods, value of flowering plants that supply nectar and pollen production, impact on other pests, beneficial for these biocontrol agents organisms and the environment  Use recommended crop waste management 5. Using strategies that may include a combina- practices to avoid attracting or maintaining pests tion of behavioural, biological, chemical, such as proper disposal of prunings, diseased/ cultural and physical methods to reduce pest infested plants/plant parts populations to acceptable levels  Manage movement of soil, plants, equipment 6. Evaluating the effects and efficacy of manage- and vehicles to avoid introduction of pests ment decisions Identification of Damage, The IPM concept has evolved in response to problems caused by an over-reliance on chemical Pests and Natural Enemies pesticides. Some of these problems are develop- An essential step in applying IPM is to correctly ment of pesticide resistance, adverse impacts identify pest damage or a specimen that might be on natural enemies of pests and other non- a pest or a biological control agent (natural target species, outbreaks of formerly suppressed enemy). The text under individual insects, mites pests, and risks to environmental, human and and diseases in this Guide tells when and where to food safety. look, describes symptoms of disease and pest IPM requires knowledge of how to identify injury and the life cycle of pests and natural pests and evaluate their damage, how to identify enemies. Correct identification ensures that the natural control agents, and how to select effective correct control product or management practice control methods that minimize undesirable side is used. If you do not recognize the pest, plant or effects. disease/ disorder, submit samples to your nearest BCMAL or Canadian Food Inspection Agency Select control options for individual pests with the office for identification. Early detection of entire vineyard management system in mind. invasive alien species will allow earlier application Many pest prevention and cultural control of management practices to eliminate the new methods are part of normal crop production problem or slow its spread. operations. 2010 Best Practices Guide for Grapes for British Columbia Growers 5-1 5 Crop Protection

Monitoring tap) to dislodge any insects onto the tray for counting. Make sure to clear the board of all Monitoring is another essential component of insects and debris between each limb tap. all IPM programs. Monitoring involves timely Insect traps can collect insect pests either by sampling of the crop or site using prescribed meth- visual attraction (e.g. yellow sticky boards) or by ods to quantify the abundance and distribution traps (e.g. earwigs). Proper placement and of pests and their damage. Also monitor natural maintenance of these traps is essential if they enemies where methods are available. Use the are to be effective. Sweep nets are useful for information to decide if and when control action collecting insects from vines and from vegeta- is required. For example, examine leaves for the tion within rows and around the vineyard. presence and abundance of mites and leafhoppers. Some monitoring and sampling equipment is As well, inspect green berries to determine the available through local grower supplies retailers. degree of powdery mildew infection. Where pest forecast models are available, monitor- Undertake to monitor regularly and consistently as ing daily temperatures and rainfall is necessary for required to get valid information. Monitoring is these computer-generated models to indicate the not only important for deciding if control is presence of a specific development stage of an necessary, but is also useful for evaluating the insect (egg, larva, nymph, etc) and to indicate effectiveness of a control treatment or practice. an infection period of a plant disease. Monitoring techniques are available for some vineyard pests and diseases. These techniques Control Decisions are used at a particular time in the life cycle of a The objective of IPM is not to control 100% of pest or disease (such as larval stage or spore the pests in a vineyard. This is neither possible release) or in vine development (such as dormant, nor desirable. The potential impact of a particu- bud growth or cap fall). These techniques also lar level of pests varies greatly depending on vine involve the use of specific sampling units (such as vigour and variety, crop value, weather conditions number of leaves or vines, one hour) and equip- and abundance of natural enemies. For example, ment (thermometer, trap, beating tray, sweep net). little leafhopper damage may result to leaves early Failure to follow the instructions as described in the season if the weather is cold and rainy. Cool can result in incorrect information and poor weather delays egg laying and hatching which control decisions. would postpone spray applications. A block of The presence of damage alone is not a clear very vigorous vines with a light crop may be able indication that treatment is necessary as the pest to tolerate much higher numbers of mites than may be gone or not in a stage susceptible to another block suffering from inadequate nutrition. control. Severity of powdery mildew varies according to temperature, moisture conditions and the degree Use a 10 to 20x hand lens to inspect plants and of infection the previous year. Because of these a notebook to record observations and num- influencing factors, the control action thresh- bers for later evaluation. Beating trays, sweep olds recommended in this Guide are only nets and insect traps are useful for capturing guidelines. insect pests and their natural enemies. Once you have reviewed the monitoring and other You can make a beating tray using white or pale relevant information, you or your advisor can then green preshrunk fabric stretched over a 45 cm x determine the need for a pesticide application. This 45 cm piece of plywood or wooden or PVC pipe task is easier if there is an economic threshold frame, to form a smooth, taut surface. Light value to follow. Otherwise you must weigh the coloured insects are easier to spot on darker economic benefit expected from the treatment cloth. Attach a handle to one side or to the against the direct and indirect costs of control. underside to make handling easier. Cover the Never protect a crop simply for ‘cosmetic’ purpos- impact end of the beating stick with rubber or es. To estimate the benefit of control, compare other soft padding to prevent injury to vines. the expected loss from the pest(s) if you do not The beating tray is held under a limb which is apply a pesticide to the cost of applying the then rapped sharply three times (= one limb

5-2 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection pesticide. Direct costs of pesticide application floor vegetation may create a pest problem. include purchase and transport of pesticide, For example, do not destroy flowering plants from application and clean-up time, protective clothing about one week prior to one week after full bloom and training and licensing requirements. Indirect of grapes to minimize western flower thrips move- costs are difficult to measure and include hazard ment up into the vines and fruit clusters and to the applicator, workers, pollinators and other subsequent damage (pansy spot). non-target species and risk of pesticide resistance development. This Guide includes information on bee poisoning, minimum days to harvest and IPM Record Keeping and relative toxicity of pesticides to help in selecting a Evaluation suitable pesticide. A very important but often neglected component Spray effectiveness varies depending on quality of of IPM is evaluating the results of pest and crop application equipment and technique, weather management programs at the end of the season. conditions, timing with respect to presence of Did the management decisions result in the susceptible stage of pest or disease and the status expected outcomes? If not, why? Such evaluation of pest resistance to the pesticide. is only possible by keeping accurate records of pest and crop management activities. Growers should IPM Control Methods record results and observations of pest, damage As previously stated, IPM involves the combined and beneficial species monitoring, and also record use of chemical, biological, cultural and other irrigation, fertilizer and pesticide applications. control methods supported by accurate pest Keep separate records for each block to form a identification, monitoring, and economic thresh- permanent record for future reference. Such olds to minimize crop losses and undesirable side information is useful to identify changes in pest effects on people and the environment. The IPM and natural enemy prevalence. Use these records programs used in grape production differ in the use to identify weaknesses and plan adjustments in of control options; however, they all involve some the programs for the next growing season by form of pest or pest damage monitoring. consulting available technical publications and advisory services. Accurate record keeping is an IPM of mites begins with avoiding use of chemi- essential component of IPM and these records may cals harmful to predatory mites. Mite IPM also be required as part of any production certification involves monitoring pest and predatory mite programs developed for the commodity. abundance and noting evidence of damage (yellowed leaves) and vigour of vines. If a miticide For various pest and disease monitoring activities, treatment is necessary, select a product that will record the date, block/variety, pest/disease name, reduce plant-feeding mites without killing preda- number found, sample size or unit, and any obser- ceous mites. vations that could useful when the pest management programs are evaluated. IPM of leafhoppers involves monitoring (for egg hatching or for foliage damage), application of an Record all pesticide and fertilizer application insecticide as needed, monitoring of parasitized activities performed by you, an employee or leafhopper eggs, and proper irrigation and consultant. Information to record includes the nutrition to ensure healthy vines. IPM of cut- application date, block ID, vine growth stage, pest worms involves monitoring developing buds in controlled, product used (trade name) and the spring for signs of feeding (buds hollowed amount per tank, rate used/ha, spray volume/ha, out), inspecting the subsoil at the base of vines pre-harvest interval and re-entry interval (as and the foliage for cutworms, and applying a stated on the label), and notes on weather recommended insecticide if required. conditions. Vineyard floor vegetation management should apply a balanced approach to minimizing rodent damage and nutrient and water competition to vines and preserving suitable habitat for some natural enemies of vine pests. Also, destruction of

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5.2 Grape Diseases Disease Diagnosis  Check that the chosen fungicide is acceptable The BC Ministry of Agriculture and Lands to your buyers; (BCMAL) Plant Diagnostic Lab in Abbotsford  provides identification of pathogenic and non- Ensure that all the cultural alternatives for pathogenic disorders affecting commercial the disease in question have been considered. crops in B.C. Instructions for submitting sam- Be cautious and accurate when pesticides are ples, including fees and submission forms, are used for pest control. Use proper equipment, located on the ministry website at: maintained in good condition and calibrated www.al.gov.bc.ca/cropprot/lab.htm. accurately. Consult the section on Pesticide Accurate diagnosis of pests and diseases is an Application Equipment in this publication for important component of integrated pest man- instructions on sprayer calibration and the agement. Selection and implementation of section on Pesticide Safety. effective disease control strategies requires Grape Powdery Mildew knowledge about the identity of a disease and an understanding of its life cycle. Any pest or Powdery mildew, also known as oidium, is disease problems that you are not familiar with caused by the fungus Uncinula necator. This should be submitted for identification. There is fungus has a narrow host range attacking only no fee charged for specimens submitted as grape plants and a few related species. It is the suspected invasive alien species. most common and widespread disease of grapevines in the Okanagan/Similkameen area. Prior to using a pesticide for disease control: Popular wine grape varieties vary in susceptibil-  Always read the label first! Follow label ity to powdery mildew (Table 5.1). instructions and precautions, and note the pre-harvest interval; Table 5.1 - Level of resistance of grape cultivars to powdery mildew Susceptible Intermediate Least Susceptible Bacchus Chelois Auxerrois Cabernet Franc Chenin Blanc Malvoisie Cabernet Sauvignon Concord Melon Chancellor Foch Pinot Gris Chardonnay Pinot blanc Semillon Chasselas Malbec Gamay Merlot Gewurztraminer Ortega Grenache Pinot Noir Himrod Perlett Madeleine Angevine Sheridan Madeleine Sylvaner Vidal Blanc Malbec Weissburgunder Muller Thurgau Pearl of Csaba Petit Verdot Rkatzeteli Riesling Sauvignon blanc Schonburger Siegerebe Syrah Viognier

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Symptoms Life Cycle Powdery mildew symptoms can be seen on The powdery mildew fungus overwinters as foliage, fruit, flower parts and canes. Mildew cleistothecia (tiny, round, black fruiting bodies), usually appears first as whitish or greenish- in bark, on canes, left-over fruit, and on leaves white powdery patches on the undersides of on the ground. Spores (ascospores) from the basal leaves. It may cause mottling or distor- overwintering cleistothecia are released in the tion of severely infected leaves, as well as leaf spring after a rainfall of at least 2.5 mm. For curling and withering. Lateral shoots are very primary infection to occur the spores require at susceptible. Infected blossoms may fail to set least 12-15 hours of continuous wetness at 10- fruit. Berries are most susceptible to infection 15°C to infect developing plant tissue. during the first three to four weeks after Once primary infection has occurred the disease bloom, but shoots, petioles and other cluster switches to its secondary phase. Secondary parts are susceptible all season. Infected berries colonies (white mildew patches) form in 7 to 10 may develop a netlike pattern of russet, and days, although the disease is not noticeable early may crack open and dry up or never ripen at in the season. The white patches of powdery all. Old infections appear as reddish brown mildew produce millions of spores (conidia) areas on dormant canes. which are spread by wind to cause more infec- Early powdery mildew infections can cause tions. Free moisture is not needed for secondary reduced berry size and reduced sugar content. infection; temperature is the most important Scarring and cracking of berries may be so environmental factor (Table 5.2). The disease severe as to make fruit unsuitable for any spreads quickly in early summer when tempera- purpose. Be aware that many winemakers have tures are moderate. The incubation time (the a very low tolerance for powdery mildew on time between infection and the production of grapes. Research has shown that infection spores) can be as short as 5 to 6 days under levels as low as 3% can taint the wine and give optimal temperatures. Shaded and sheltered off-flavours. locations favour mildew development. High temperatures and sunlight are inhibitory to powdery mildew. Extended periods of hot weather (>32°C) will slow the reproductive rate of grape powdery mildew, as well as reduce spore germination and infection.

Table 5.2 - Effect of temperature on the development of grape powdery mildew Temperature of leaf* Days for spores to develop, infect vine parts and (oC) produce new spores 6 32 9 25 12 18 15 11 17 7 23 6 26 5 30 6 33 (for at least 3 days) 0 (but 10% can recover in 5 days) 40.5 (for at least 6 hrs) 0 (kills the fungus)

* Note: Leaf temperature can be slightly higher or lower than air temperature.

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Control approximately one week later and what the potential disease severity will be two weeks Cultural Control: later, allowing them to plan their fungicide 1. Manage canopies to increase air drainage and program in terms of product and application light penetration by removing lateral shoots interval. Several years of data from many in dense canopies. If necessary remove leaves different sites around the Okanagan and in the fruiting zone. Dense canopies provide Similkameen indicate that the risk mode low light intensity, which favours powdery consistently predicts severe powdery mildew mildew development; and the shortest interval between fungicide 2. Use an under-vine irrigation system (drip or sprays in July and August. Typical Okanagan micro-jet); temperatures during the summer months are 3. Manage irrigation carefully. Excessive irriga- optimum for powdery mildew. tion leads to excessive vigour and higher For more information on powdery mildew disease potential; forecasting models, refer to the University of 4. Select varieties that are less susceptible to California website at: mildew (Table 5.1) ww.ipm.ucdavis.edu/DISEASE/DATABASE/ grapepowderymildew.html. If not using a disease Fungicides and Disease Forecasting: forecasting model, apply powdery mildew con- Start mildew programs before the overwintering trol materials as frequently as necessary when fungus can infect new growth. General recom- severe mildew conditions exist, keeping in mind mendations are to begin spray coverage between the leaf temperature and the number of days budbreak and early shoot growth. The most needed for spores to infect grape parts and important fungicide timings in this area are the produce new spores (Table 5.2). blossom spray (generally just before or just after blossom) and the spray immediately following Spray Schedule the blossom spray. Protective fungicide treat- Protect grape foliage from primary infection by ments prevent infection of grape tissue by fungal application of fungicides from early shoot spores. Good coverage is important. growth until after bloom. Good control early in A mildew risk model can be used to forecast the season to prevent establishment of the disease severity of secondary infections. The disease is the key to preventing a powdery UC model developed at the University of mildew epidemic later in the summer. California, Davis is the one most widely availa- Apply fungicides such as Kumulus (sulphur), ble and is sold with weather instrument Nova, Lance, Sovran, Flint, Milstop or Serenade software. The UC model requires a data logger at the following growth stages (also see “Fungi- for leaf wetness and temperature. Initially the cide Notes” below for more information). model predicts primary infection based on 1. When new growth is 5 to 10 cm long hours of leaf wetness and temperature and then switches to the risk phase based only on 2. Just before or immediately after bloom. temperature. The risk indices can be used to 3. Every 10 to 14 days until grapes begin to help time fungicide applications. When the risk soften and red varieties begin development of is high the model recommends that fungicides colour and white varieties change from green be applied more often. In trials in California, to white or yellow. If Kumulus (sulphur) is the model has reduced the amount of fungi- used, shorten the spray interval to 7-10 days. cides applied to grapes. In tests in the Contact your winery at the beginning of the Okanagan, the primary phase of the model has season to determine the acceptable pre-harvest not been accurate and more research is re- intervals for any pesticides or sulphur products quired to adapt the model to local conditions. that may be used in the growing season. Some However the risk phase of the model could be products contribute to the development of off valuable for assessing the risk of secondary odours and off flavours and may interfere with infection during the growing season. Daily the fermentation process. analysis of the model allows the grower to visualize what the conidial population will be 5-6 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection

Dormant spray: Lime Sulphur is effective at Post-harvest powdery mildew spray: Post- suppressing the overwintering population of harvest sprays to control powdery mildew are powdery mildew. It should be applied in early beneficial. Harvest date will determine the need spring before bud break to dormant vines to to keep foliage and canes protected. Severe kill powdery mildew cleistothecia (initial powdery mildew conditions are generally a inoculum). Good spray coverage of dormant result of poor control of this organism during vines is important. the growing season. Additional sprays for powdery mildew under such conditions after harvest will not protect canes. Table 5.3 - Fungicides registered for control of powdery mildew on grape Active Chemical PHI2 Fungicide Rate/ha Rate/acre Notes Ingredients Group1 (days) Excellent mildew fungicide. Apply on a 14 day 300-480 122-194 interval. Do not exceed 5 applications/season. Quintec quinoxyfen 13 14 Use higher rate for severe disease conditions. ml/ha ml/acre Alternate with other fungicides. See Fungicide notes. Excellent mildew fungicide. Apply preventively trifloxystrobin 105- 43-57 using a 14-21 day interval. Do not use Flint or Flint 11 14 other group 11 fungicides more than 2 times per 50% WG 140g/ha g/acre season. Alternate with fungicides from other groups. See Fungicide notes. Excellent mildew fungicide. Apply at 14-21-day kresoxim- 240-300 100-122 intervals. Do not use Sovran or other group 11 Sovran methyl 50% 11 14 fungicides more than 2 times per season. Alter- g/ha g/acre WG nate with fungicides from other groups. See Fungicide notes. Excellent mildew fungicide; also provides pyraclostrobin 420-735 170-300 suppression of botrytis. See label for details on Pristine 11 + 7 14 rates and spray intervals. Do not use Pristine or + boscalid g/ha g/acre other group 11 fungicides more than 2 times per season. boscalid 70% May also provide some suppression of botrytis Lance 7 315 g/ha 128 g/acre 14 bunch rot. Alternate with fungicides from other WDG groups. Excellent mildew fungicide. Apply at 21-day myclobutanil intervals. Do not use more than 2 times per Nova 3 200 g/ha 81 g/acre 14 40% season. Alternate with fungicides from other groups. Kumulus Good mildew fungicide. Apply at 10-day inter- sulphur 80% M 4.2 kg/ha 1.7 kg/acre 21/13 DF vals. 2.25 kg/ha 910 g/acre pre-bloom pre-bloom wettable Use the higher rate when vines are in full leaf. sulphur 92% M 4.5-6.0 1.8-2.4 21/13 sulphur Apply at 10-day intervals. Re-apply after rain. kg/ha post- kg/acre bloom post-bloom Milstop potassium 2.8-5.6 1.1-2.3 NC 0 Apply at 7-14 day intervals bicarbonate kg/ha kg/acre Serenade 3.0-6.0 1.2-2.4 Bacillus subtilis NC 0 Biofungicide. Disease suppression only. MAX kg/ha g/acre 120 Apply 500L of spray mixture per hectare once Lime sulphide 100 L lime sulphur in per season during dormant stage prior to bud M (apply sulphur sulphur 1000 L of water swell (early March to early April). Spray to point dormant) of runoff, cover completely. 1 Chemical Group: Products with the same number belong to the same class of compounds. Alternate products with different chemical groups to help delay or prevent the development of resistance 2 PHI = Pre-harvest Interval, or minimum number of days between last spray and harvest. 3 Sulphur can be used on table grapes up to the day of harvest (1 day PHI), but the pre-harvest interval for wine grapes is 21 days. Excessive amounts of sulphur are detrimental to winery yeasts. It is suggested that the last application to wine grapes be made not later than 30 days before harvest. Check with the winery before application of any fungicides within the last month. 2010 Best Practices Guide for Grapes for British Columbia Growers 5-7 5 Crop Protection

Fungicide Notes vals under low disease pressure. To help prevent the development of resistance, limit the use of Resistance Management group 11 fungicides to a maximum of 2 times Grape powdery mildew has developed re- per season, and never make more than 2 appli- sistance or reduced sensitivity to sterol- cations in a row. Alternate with at least 2 inhibiting fungicides (Nova) and to strobilurin applications of fungicides in different chemical fungicides (Flint, Sovran, Pristine) in other areas groups (see table 3). Caution: Sovran drift may such as Eastern North America. Avoid over- cause severe injury to certain cherry and Asian using these products to prolong effectiveness in pear varieties. this area. Pristine contains 2 fungicides; one is in the To help prevent resistance from developing: same class as Flint and Sovran and at high risk of resistance. Begin applications prior to the  Alternate between different fungicide groups. onset of disease. Use a 10-14 day interval if Do not use more than 2 back-to-back sprays using the low rate, or a 21 day interval if using of fungicides with the same group number the high rate. To help prevent the development (see table 3 for group numbers). of resistance, limit the use of Pristine (and other

 Limit the number of sprays of products with a group 11 fungicides including Sovran and Flint) high risk of resistance (Nova, Sovran, Flint, to a maximum of 2 times per season. Alternate Pristine) to 2 per season per chemical group. with fungicides from different groups (see table Mildew fungicides with a low risk of re- 3). Pristine also suppresses botrytis bunch rot. sistance include Kumulus, sulphur, lime sulphur, Milstop and Serenade. Lance has a Nova is a strong fungicide for control of moderate risk of resistance. powdery mildew, however powdery mildew has  Use only recommended dose rates. developed a reduced sensitivity to Nova in some  Ensure sprayer is properly calibrated to areas of the world. To prevent the development deliver accurate and thorough coverage. of resistance, alternate Nova with other fungi- cides and do not use more than 2 times per  Integrate with non-chemical control methods. season. Nova is locally systemic. Once absorbed  Discontinue use of a product if resistance is by the plant, it can not be washed off by rain. suspected and consult your crop advisor. Do not apply Nova with copper fungicides such Sulphur is currently the most common fungi- as fixed copper, copper oxychloride, copper cide used for powdery mildew control in the BC sulphate or other copper containing products Interior in both conventional and organic because this combination reduces the effective- vineyards. Kumulus DF is a dry flowable for- ness of Nova. mulation of sulphur. The addition of a wetting Lance provides some suppression of bunch rot, agent will help to improve the distribution of in addition to control of powdery mildew. wettable sulphur over the plant surfaces. How- Apply on a 10-14 day schedule. Use the shorter ever, the use of these agents may cause more interval when disease pressure is high. Rotate Botrytis infection. Too much wetting agent will with other fungicides for resistance manage- cause excessive foaming in the sprayer. Fruit ment. and leaf “burning” may occur if sulphur is applied during slow drying conditions or when Quintec was registered June 2010 for control temperatures are above 27°C. Do not apply of powdery mildew in grape. It is a protectant sulphur to Concord, Sheridan or Foch. fungicide, best used before visible mildew is present. Use the higher rate during high mildew Sovran and Flint are strobilurin fungicides pressure conditions. Rotate with fungicides which provide good control of powdery mil- from other chemical groups for resistance dews. These products are in the same class of management. Quintec does not provide control compounds (group 11) and are at high risk of of botrytis bunch rot. resistance. Use the higher rate under heavy disease pressure. Use 14-day intervals under Milstop is a contact fungicide that controls moderate to heavy pressure, and 21-day inter- powdery mildew. It does not provide control of botrytis. It is considered a weaker product than 5-8 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection sulphur, but provides a good alternative for use Making Tank-Mix Bordeaux on sulphur-sensitive cultivars and is another rotational product for resistance management. 1. Start water flowing into spray tank. Apply using a sufficient volume of water to insure complete coverage of all stems and 2. When tank is about one-third full and the foliage. Use the high rate and short application mechanical agitator is in operation, start interval (7 days) when conditions favour the washing the powdered copper sulphate into development of powdery mildew. OMRI the tank through a screen with water from approved for organic production. the supply hose. A wooden spoon is often helpful in working powdered copper sul- Serenade Max is a biofungicide derived from phate through the screen. Pre-soaking the the beneficial bacterium Bacillus subtilis. It is copper sulphate in a plastic bucket of hot registered for "suppression" of powdery mil- water will speed up the process. dew, and will also provide some suppression of bunch rot and sour rot. OMRI approved for 3. By the time the tank is two-thirds full, all of organic production. the powdered copper sulphate should be in Bordeaux Mixture is a broad-spectrum fungi- the tank. Then wash the lime (hydrated or cide and bactericide that is not easily washed off builders’) through the screen, using the water by rain. Experience in Ontario indicates post supply hose, into the copper sulphate tank. harvest Bordeaux sprays using copper sulphate The lime should be as dilute as possible be- as a copper source to control late powdery fore it meets the copper sulphate solution in mildew infections also appear to be an aid to the tank, so use lots of water to wash lime increased bud hardiness and improved wood through the screen. Pre-soaking the lime be- maturity in older vines. Sprays of fixed copper fore adding to the tank may be preferred to to young vines one month before the first fall washing powdered lime directly through the frost appear to help “induce” some level of bud screen into the tank. hardiness and wood maturity.

Copper sulphate (Bordeaux) is registered for 4. Keep the agitator running continuously and several grape diseases including downy mildew, apply the Bordeaux mixture immediately. black rot and dead arm. It is not a strong powdery mildew fungicide, but may be useful for post-harvest control of light mildew prob- lems, or as part of a mildew program on sulphur-sensitive varieties. Do not mix copper with other fungicides or insecticides. Copper applied under cool, slow drying condi- tions may cause injury, even to so called tolerant varieties. Copper oxychloride is less injurious to plant tissue than copper sulphate. Addition of the lime helps to minimize, but may not prevent injury. The label rate for copper sulphate on grape is 3 kg copper sulphate + 6 kg hydrated lime in 1,000 L water/ha. Also used is copper ox- ychloride (50% copper) at 3 kg + 6 kg hydrated lime in 1,000 litres of water.

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Botrytis Bunch Rot of Grape Table 5.4 Time/temperature relationships for botrytis bunch rot infection Botrytis bunch rot, caused by the fungus Botrytis Temperature Amount of Time cinerea, is a common problem wherever grapes o are grown. The disease can cause serious losses 10 C 30 hours or more in both yield and quality when weather condi- 15.5 oC 18 hours or more tions favour the disease. 22.5 oC 15 hours or more Symptoms 26.5 oC 22 hours or more 39 oC 35 hours or more Ripening grapes are affected by a rot which may progress to infect whole clusters. With sufficient Slow drying conditions together with high rain and humidity, berries split open and devel- humidity (90% or better) favour the develop- op a greyish mold on the surface. Affected ment of botrytis. Table 1 indicates the berries may shrivel in the dry Okanagan climate. temperature required plus the corresponding Botrytis may cause girdling lesions on the period that slow drying conditions must exist pedicel or rachis, leading to drying of clusters or for bunch rot infection to occur. portions of clusters, and premature cluster drop. Cultural Control Infection and Spread During the growing season Botrytis infects grape shoots, flowers, leaves and  Avoid overhead irrigation and keep irrigation fruit under a range of temperature and humidity periods as short as possible. conditions (Table 5.4). Infection is optimal at  15-20 °C with free water or over 90% humidity. Prevent excessive vine growth by judicious Grape cultivars with dense canopies, thin skins use of water and fertilizer. and/or tight clusters are more susceptible to  Canopy management and leaf removal botrytis bunch rot (Table 5.5). before fruit set will reduce botrytis bunch Botrytis overwinters as mycelium or sclerotia on rot. Remove leaves and lateral shoots located bark and as mycelium in dormant buds. It may opposite, one node above, and one node be- also overwinter in mummified fruit. In the low each fruit cluster. spring, conidia (spores) are produced which can  Prevent berry damage by effective control of infect leaves and young clusters before bloom. powdery mildew early in the growing season. The fungus may infect blossoms leading to fruit  Minimize berry damage by birds and insects. infection, but the fungus becomes inactive (latent) in the fruit possibly due to low sugar During the dormant season and high acid contents. It becomes active again  Knock mummified fruit and infected prun- when the berries begin to soften. Fruit infection ings to the ground and cover with soil, or usually begins in berries with 5 to 8 percent alternatively burn. sugar (at veraison), with berries remaining susceptible up to harvest and also post-harvest. Chemical Control Abundant conidia are produced on infected Fungicides registered for the control of botrytis fruit, leading to secondary spread to adjacent include Rovral (iprodione), Vangard (cyprodi- berries in a cluster and to nearby clusters. nil), Elevate (fenhexamid) and Scala Spread of the spores is aided by summer rains, (pyrimethanil) (See Table 5.6). These fungicides overhead irrigation, heavy dew and juice from represent 3 different chemical classes. Note split berries. Spores are also carried by the wind. that Scala and Vangard belong to the same Mechanical damage caused by birds or insects class, with the same mode of action. Alternate creates entry points for the fungus and can fungicides from different classes to help greatly increase losses due to bunch rot. prevent the development of resistance. Note that none of these fungicides provides any significant control of powdery mildew.

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Table 5.5 Susceptibility of grape varieties in British Columbia to botrytis bunch rot Very Susceptible Moderately Least Susceptible Susceptible Susceptible Auxerrois Optima Barbera Ortega Cabernet Franc Bacchus Pinot Blanc Kerner Scheurebe Cabernet Sauvignon Chardonnay Riesling Lemberger Schoenburger Chancellor Chasselas Semillon Malbec Syrah Foch Chenin Blanc Siegerebe Muscat Ottonel Vidal Merlot Ehrenfelser Zinfandel Pearl of Csaba Viognier Petit Verdot Gamay Noir Pinot Gris Madeleine Angevine Pinot Meunier Madeleine Sylvaner Pinot Noir Sangiovese

Sauvignon Blanc

Correct identification of botrytis bunch rot Key timings for botrytis fungicide applications prior to applying fungicide sprays is important. are bloom, just before bunch closing, veraison Botrytis can be confused with other rots such as and pre-harvest. Botrytis control becomes more sour rot. Application of botrytis fungicides difficult as the grapevine matures because heavy where sour rot is present may increase the level canopy growth and bunch closing make it of sour rot infection. difficult to place the fungicide where it is need- ed. The number of spray applications necessary to control bunch rot depends upon disease pres- Under typical Okanagan weather patterns, high sure in the vineyard and weather conditions, as risk periods for botrytis infection are during well as other factors such as susceptibility. bloom and from 1 to 2 weeks after veraison to Fewer applications may be needed if weather is harvest. These growth stages often coincide very dry and/or disease pressure is low. Use a with rainy periods during June and September. full program in vineyards where bunch rot was a Be cautious about adding spreaders or stickers serious problem in the previous year, and where to fungicide sprays, as some spray adjuvants sanitation measures were not taken after har- have been shown to increase the development vest. The number of sprays can be reduced or of bunch rot on grape clusters. It is believed eliminated in vineyards with a history of low that spray adjuvants remove the natural wax disease levels and for all vineyards in dry years. protection on grape berries.

Table 5.6 Fungicides registered for bunch rot suppression and control Active Chemical Fungicide Rate/ha Rate/acre PHI2 Comments Ingredients Group1 Rovral iprodione 50% 2 1.5kg/ha 600g/acre 7 Maximum 2 sprays/season fenhexamid 17 1.12kg/ha 450g/acre Elevate 7 Maximum 3 sprays/season. 50% pyraclostrobin 7 + 11 420-735g/ha 170-300g/acre Registered as suppression only for 12.8% Pristine 14 botrytis bunch rot. Maximum 2 + boscalid sprays/season. 25.2% pyrimethanil 9 2.0L/ha 810mL/acre Scala 7 Maximum 3 sprays/season. 400g/L Vangard cyprodinil 75% 9 750g/ha 300g/acre 7 Maximum 2 sprays/season. Serenade Biofungicide. Disease suppression Bacillus subtilis NC 3.0-6.0kg/ha 1.2-2.4kg/acre 0 MAX only. 1 Chemical Group: Products with the same number belong to the same class of compounds. Alternate products with different chemical groups to help delay or prevent the development of resistance. 2 Pre-harvest Interval 2010 Best Practices Guide for Grapes for British Columbia Growers 5-11 5 Crop Protection

Grape Sour Rot Cultivars with tight clusters and thin skins are generally more susceptible to sour rot. Very Sour rot has not been a commonly recognized vigorous vines seem to be more prone to the problem in the Okanagan/Similkameen, but it disease due to tighter bunches with berries more was a serious issue in many vineyards during the likely to burst, and also due to a higher moisture 2004 growing season. Varieties which were environment. affected include Pinot Blanc, Pinot Gris, Ries- ling, Pinot Noir and Chardonnay. It is likely that The onset of hot, dry weather can lead to the sour rot has always been present, but it may drying of the infected and damaged berries, have been confused with botrytis bunch rot in thereby slowing the spread of the disease. Cool the past. Sour rot affects both crop yield and weather will considerably slow fruit fly popula- wine quality. Infected fruit can give an unpleas- tion growth, in turn leading to a reduction in the ant flavour to the finished wine and push spread of the disease. volatile acid beyond acceptable levels. Some local and Californian observations indi- Symptoms cate that the use of botrytis fungicides during periods favourable to sour rot development may Symptoms include a soft watery rot with leakage increase damage caused by sour rot. Some of berry juice, and a distinctive vinegar smell. experts speculate that the fungicide may kill the Large numbers of fruit flies, (also known as micro-flora present on the berry surface. These vinegar flies) and fruit fly larvae are generally organisms may have some protective effect present. The fruit flies produce ethyl acetate, a against the yeasts and bacteria responsible for common fault in wine. There is very little sour rot. However, research done in Italy in the tolerance of fruit contaminated with ethyl early eighties found that powdery mildew and acetate. Sour rot appears similar to botrytis botrytis control, together with fruit fly control, bunch rot. Affected berries are brick-coloured significantly reduced the incidence of sour rot. in white cultivars and purplish-brown in red cultivars. Prevention and Control Disease Cycle  Reduce excessive vigour through the use of cover crops and/or the reduction of nitrogen Sour rot is caused by a number of undesira- fertilization and irrigation. ble yeasts and bacteria, often in association with other fungal rot diseases including  Leaf removal between fruit set and veraison Botrytis, Penicillium and Rhizopus. Causal agents can lead to tougher berry skins, thereby re- of the 2004 Okanagan outbreak of sour rot ducing the risk of lesions. are under investigation.  Control wasps through trapping and nest Sour rot pathogens gain entry into grape berries removal. through cracks and wounds caused by wasps,  Control powdery mildew to reduce grape hail, birds, powdery mildew, botrytis, or by berry lesions, which attract fruit flies. berry splitting caused by excessive vigour in  Prevent bird damage. tight clusters. Such injuries attract fruit flies which also effectively carry and spread the  Bunch thinning is best done before or during disease-causing organisms. During favourable veraison. Berries removed during late season conditions (warm moist weather, sugar accumu- thinning have higher sugars which can con- lation in berries) the fruit fly will lay hundreds of tribute to the fruit fly population increase. eggs and start a new generation every ten to  Discard affected bunches before or during twelve days. Under the right conditions this can harvest to minimize the negative effects on lead to explosive disease outbreaks. Fruit left on the wine. the ground from post-veraison bunch thinning  No insecticides are registered for the control can also be a contributing factor to build-up of of fruit flies on grape. Fruit flies quickly be- fruit fly populations. come resistant to most chemical control

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products due to their fast rate of multiplica- Before Planting tion. Losses of grape plants due to crown gall may be  Some French sources recommend 2-3 minimized with some considerations before applications of Bordeaux mixture (copper vineyard sites are selected and before vineyards sulphate and hydrated lime) at ten to twelve are planted. Criteria to consider include the day intervals around the time of veraison. following: Copper applied to the fruiting zone has the  Select sites with good air and water drainage. effect of thickening the grape berry skin, hence reducing the risk of lesions. See fungi-  Avoid planting in frost-prone areas. cide notes under powdery mildew for more  Select rootstocks that are resistant to crown information on copper fungicides. gall. Certain rootstocks such as Courderc 3309, 101-14 Mgt, and Riparia Gloire are Crown Gall of Grape resistant, whereas Teleki 5C and 110 Richter are susceptible. See Table 3.2 (Characteristics Crown gall is an important disease of wine of important grape rootstocks) on page 3-19 grapes when they are grown in cold climates. of the Grape Management Guide for resistance Gall formation on the aerial part of the vines is ratings. Resistant rootstocks can reduce the the most common symptom associated with this amount of crown gall that appears on sus- disease. The bacterium which causes crown gall ceptible scions. may be present in plants that do not show any  Select hardy varieties where possible. symptoms. Most grape cultivars are susceptible  to crown gall. Major outbreaks are generally Prepare sites with nutrients and lime before planting to avoid vine stress due to poor nu- restricted to the varieties that are most suscepti- trition or low pH. ble to winter injury. The amount of crown gall present from year to year appears to be related  Consider pest control programs for nema- to the severity of the preceding winter and the todes and phylloxera before planting through maturity of the vines. the use of soil fumigation or rootstocks. Feeding damage by these pests provides sites A major source of diseased vines appears to be for the entry of crown gall bacteria. through propagation of diseased wood. The bacterium remains inside the vine until there is  Plant old vineyard areas where crown gall an injury to the trunk and only then invades was present only after grapevines have been the outer part of the trunk where it causes removed for at least 2 years. This is im- rapid cell multiplication and distortion of tissue portant because crown gall bacteria can producing galls. survive in the remnants of the old grape plants until the debris decomposes. Success Galls are usually noticed as swellings near the in reducing crown gall from the soil by leav- base of the vine and up the trunk. Galls on ing soil fallow or rotating to other crops may roots of grape are not typical, however the vary depending on the amount of vine debris bacteria can induce a localized necrosis of roots. that is left in the soil, and how fast it breaks Young galls are soft, creamy to greenish in down. colour, with no bark or covering. As they age,  Do not propagate wood taken from galled the tissue darkens to brown. The surface be- vines. comes open and the texture becomes moderately hard and very rough. The surface  Specify that plant material you purchase be tissue of the galls turns black as it dies, but the propagated from crown gall free plants. Pro- bacterium remains alive in the vine. ducers must promote the production of certified indexed crown gall free vines. Control After Planting Control of crown gall can at best be referred to There is little that can be done to control this as an attempt to manage this disease. disease once it is established in the vineyard. Avoid injury to vines (winter, mechanical and human). Remove suckers when shoots are small 2010 Best Practices Guide for Grapes for British Columbia Growers 5-13 5 Crop Protection

(3 to 6 cm) to reduce trunk damage and pro- Grape Virus Diseases mote rapid healing of wounds. Removing larger shoots before they harden will result in clean What is a virus? and small scars. Grape virus diseases are caused by microscopic  Hill young vines with 30 cm or more of soil particles that are composed of genetic material or other material to protect them from cold (DNA or RNA) inside a protective protein coat. temperatures. Remove this material carefully Viruses are much smaller than bacteria and to avoid mechanical damage. fungi, and require very specialized tests for their detection. Once inside a living plant, viruses  Prune to delay budbreak (late pruning) on varieties prone to early bud break. have the ability to multiply by taking over plant cells and reprogramming them to make more  In France, application of K2O instead of virus particles. In grapevines the virus will nitrogen fertilizers is used to improve re- spread systemically to all parts of the vine (roots sistance of the vines to cold. and vegetative parts). Once a plant is infected, it  Biological control of grape crown gall has will remain so for life. been effective in trials, and is a promising General Virus Symptoms management tool for the future. Viruses cause a wide range of symptoms, ranging from no visible symptoms to plant death. Many grapevine viruses cause a general decline in vigour and productivity, and delayed maturity. Other symptoms may also be present on foliage, stems, leaves or fruit. It is possible for a virus to infect a grapevine without the plant showing any obvious symp- toms (called a latent virus or sleeping virus). The degree of virus symptom development and effect on a plant is influenced by the virus strain, plant variety, and environment. A previously latent virus may become more virulent (or more severe) at some time due to changes in the environment or through propa- gation, often onto a different rootstock. The symptoms may be subtle, requiring proper experiments to demonstrate the effects of the virus. For example, the involvement of a virus may not be obvious in an increased susceptibil- ity to winter injury or a gradual decline in yield. Symptoms such as graft rejection, rapid decline of vines, severe stunting, late blossom and late or poorly ripening fruit are more obvious. Foliar, fruit or cane symptoms of virus diseases are also frequently visible. These may include any one of the following: red foliage (on red varieties), short internodes, mottling of leaves, fasciation of canes, double internodes, exces- sive growth from secondary buds, straggly bunches with both large and small berries, rolling of the leaves in the fall, wood pitting and grooving, etc.

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Importance of Virus Diseases and moved from the weeds to grapevines. Virus diseases can have a serious impact on Other viruses are transmitted by soil fungi or vine health, yield and quality of the fruit. insects such as aphids, leafhoppers, psyllids and Symptoms are not always severe or obvious, mealybugs. Mealybugs and soft scale insects are but even a small decrease in yield will add up known to be vectors of some of the grapevine over time causing significant economic losses. leafroll-associated viruses, Grapevine virus A Decreased yields of 5 to 10% are not uncom- (causing Kober stem grooving disease, formerly mon for grapevine viruses, and losses can be Grapevine stem grooving virus), and Grapevine virus B much higher. Viruses may also influence wine (causing grapevine corky bark disease). quality by causing delays in sugar accumulation, There are also virus-like diseases for which poor acid development, and poor colour the method of transmission (apart from development. propagative) is not known or well document- The difficulty of detecting virus infection can ed. This group includes many damaging lead to rapid dissemination of virus-infected diseases such as Grapevine Enation, Grape- material through propagation. When infected vine Yellow Speckle, and Grapevine Shoot cuttings are used for propagation, whole vine- Necrosis. Little is known about some of these yards can become infected. viruses beyond the symptoms they cause. This lack of knowledge forms a serious obstacle to How Viruses are Spread effective disease management. Humans are the most effective transmitter of Control and Prevention of Viruses virus diseases through movement and propaga- tion of virus infected rootstocks, cuttings and  Prevention of virus diseases is critical, as finished plants. there are no cures for virus-infected vines other than vine removal. Most viruses also have other methods of spreading, although not all are known. Insects  Plant only fully virus-tested vines to reduce or other organisms that spread viruses are the risk of introducing virus diseases into known as “vectors”. Many serious grapevine your vineyard. viruses are classified as “nepoviruses” which are  If an insect vector is known to spread a transmitted by certain species of nematodes. virus, controlling the insect may help to Examples of nepoviruses include Grapevine limit or reduce the rate of spread within a fanleaf virus, Arabis mosaic virus, Tomato black ring vineyard. virus, Tomato ringspot virus, Tobacco ringspot virus,  Canada has specific grapevine import regula- Peach rosette mosaic virus and many others. These tions that help to protect grape growers from viruses can cause significant economic losses. the introduction and spread of virus diseases The nematode feeds on the roots of infected and other pests which are not yet established vines and retains the virus for several months. in British Columbia. Selected grapevine var- The disease is spread as the infected nematode ieties/clones and rootstocks from Canadian- feeds from grapevine to grapevine. Infected approved nurseries in France and Germany nematodes may be spread on the roots of are currently approved for importation into nursery plants and through soil water (irrigation, Canada. Under this program tests for regu- seepage, flooding). Fortunately plant protection lated viruses/pests of grapevines are carried measures that require treatment of imported out both in the exporting country and in planting stock have prevented the most damag- Canada, prior to the approval for the impor- ing virus-vectoring nematode of grapevines, tation of any variety and rootstock. Canada Xiphinema index, from being introduced into has different import requirements for grape- British Columbia. However, other nematodes vines from the U.S, because of the similar found in British Columbia, such as Xiphinema pest situation and the proximity of the two americanum, are known to vector nepoviruses. countries. For more information on import- Some of these nepoviruses may also be spread ing grapevines, contact the Canadian Food through seeds of infected weeds in the vineyard. Inspection Agency (CFIA). They may then be picked up by the nematodes 2010 Best Practices Guide for Grapes for British Columbia Growers 5-15 5 Crop Protection

 Note that important viruses such as Arabis associated viruses 1 and 3 in both Ontario and mosaic virus, Grapevine fanleaf virus and the vi- British Columbia. Leafroll 3 was the most ruses causing grapevine leafroll disease have commonly found virus, but the other viruses been removed from the federal quarantine were present at very low levels in British Co- pests list. Although CFIA-approved foreign lumbia. For example, out of 1485 BC samples, certification programs are supposed to pro- only 1 positive was found for fanleaf virus, and duce plants free of these viruses, their only 5 positives for arabis mosaic. Although the removal means that foreign nurseries ap- survey was not detailed enough to determine proved to ship grapevines into Canada no incidence, the low number of positives is an longer have to prove their vines are free of encouraging indication that BC remains largely these viruses. Grapevines infected with free of these damaging viruses, and it is worth- these viruses have been imported since this while to continue to prevent introduction de-regulation. It is recommended that through careful screening of nursery stock. growers importing vines request that they However, additional grapevines infected with be tested for these viruses in the country of these viruses have been imported since 1995. origin. These viruses cause serious econom- ic diseases. Grapevine Fanleaf Virus Clonal Selection Fanleaf degeneration disease caused by Grapevine fanleaf virus is thought to be the most serious Removal of viruses from plant material is grapevine virus disease. The severity of symp- possible, but requires heat treatment of the toms varies by cultivar. vines to “kill” the virus. This process is both expensive and time consuming, as it must be Symptoms verified that the virus was successfully removed. Infected leaves are often malformed with Such vines then become the foundation for abnormally gathered primary veins, giving the propagation programs designed to produce leaf the appearance of an open fan. Other “clean” vines for industry. Vines that are to be symptoms may include a yellow mosaic pattern subjected to heat treatment should be chosen on leaves or bright yellow bands along major carefully, so that only the very best varieties or veins. Fan-shaped leaves may or may not be clones are selected. The CFIA Laboratory at present with mosaic or veinbanding symptoms. Sidney, British Columbia (Centre for Plant Health) provides testing, virus indexing and Affected vines tend to be smaller than healthy therapy for viruses of grapevines, tree fruits and vines. Sensitive varieties show progressive other crops. These tested mother plants may decline, low yields (up to 80% losses) and low then be placed in a Nuclear collection (reposito- fruit quality. The productive life of the vineyard ry) at the Sidney Lab or become mother plants is shortened and winter hardiness is decreased. for growers or nurseries. Propagative material Transmission from these mother plants may be used to produce other plants for certification under the Fanleaf virus is transmitted by the nematodes Canadian Export Certification Program for the Xiphinema index and X. italiae, which have never eventual establishment of healthy vineyards. been found in Canada. There are no natural weed hosts. Long distance spread occurs pri- Major Grape Virus Diseases marily by movement of propagation material from infected plants. There are over 50 different viruses and viroids that infect grapevines distributed throughout Grapevine Leafroll - the world. Several are known to exist in Canada already. With increasing international trade and Associated Viruses travel it is expected that more of these viruses Grapevine leafroll is probably the most wide- will arrive. spread virus disease of grapevines world-wide. A national grapevine virus survey in 1994-1995 There are currently 9 different viruses associated found vines infected with Arabis mosaic virus, with leafroll, but Grapevine leafroll-associated viruses Grapevine fanleaf virus and Grapevine leafroll- 1 and 3 are most commonly found. In the 5-16 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection national grapevine survey conducted in 1994- Transmission 1995, GLRaV-1 was present in 1.0% of samples tested, whereas GLRaV-3 was present in 10.5% Long distance spread occurs primarily by of samples tested nationally. Since then Grape- movement of propagation material from infect- vine leafroll-associated viruses 2, 4 and 5 have been ed plants. Arabis mosaic virus is transmitted by the detected in imported grapevines. nematode Xiphinema diversicaudatum, which has been found in scattered locations in Canada. Symptoms This virus can also infect many other herba- ceous and woody hosts such as raspberry, Leafroll virus has impacts on both vine health strawberry, rhubarb, cherry, peach, and plums. and grape quality. Growth and yield may be reduced by 10-70%. The virus reduces yield by Rupestris Stem Pitting Virus inhibiting cluster formation and development. Infected vines have an increased sensitivity to Rupestris stem pitting associated virus-1 is a common environmental stress. Impacts on quality and widespread virus of grapevines. It is not included delayed maturity of grapes, a 25-50% regulated in Canada or the USA. A recent reduction in sugar content, and poorly col- survey found this disease in 4.6% of the samples oured fruit. in Washington State. Typical leaf symptoms include reddening of the Symptoms leaves between major veins in red varieties, and Rupestris stem pitting causes a slow decline in yellowing of the leaves between major veins in growth, resulting in vines that are smaller than white varieties. Leaves become thick, brittle, and normal with reduced yields. No leaf discolora- roll downwards. tion is observed. The disease affects only Transmission grafted vines; ungrafted vines may be infected, but usually do not show symptoms. Small pits Long distance spread occurs primarily by may develop in the wood on rootstocks, in movement of propagation material from infect- particular V. rupestris and American rootstocks. ed plants. Several mealybug and soft scale insect The severity of the disease is more pronounced species have been shown to transmit leafroll in vines that are infected with other viruses of associated viruses under experimental condi- the Rugose wood complex, including Grape- tions. Rapid leafroll spread has been reported in vine virus A (GVA) and Grapevine virus B European vineyards having significant insect (GVB). GVA is associated with kober stem vector populations. In California, increasing grooving disease. Affected vines may show natural spread within vineyards has been ob- swelling at the graft union and fail to thrive. served. The common grape mealybug GVB is associated with corky bark disease, (Pseudococcus maritimus) which occurs in the which may cause an incompatibility to develop Okanagan is a vector of GLRaV-3. at the graft union. Leaf symptoms resemble Arabis Mosaic Virus those of leafroll virus but are more severe. Symptoms Transmission Spread is mainly through propagation. There is The most common symptoms include leaf no known insect vector for Rupestris stem pitting mottling and flecking, stunting and leaf defor- virus. GVB can be transmitted by some species mation including enations. Many infections are of mealybugs. Disease management depends latent and plants do not show symptoms. upon use of certified healthy, virus-free stock. Symptoms can vary greatly by variety, rootstock Remove vines showing suspicious symptoms. and environment conditions. Yield losses of up to 50% may occur through reduced growth, dieback and severe dropping of fruit.

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Grapevine Phytoplasma Symptoms Diseases All grapevine yellows diseases have similar symptoms, including growth reduction, leaf Phytoplasmas are microscopic plant pathogens, discolouration, downward rolling of leaves, and similar to bacteria, but much smaller and lacking reduced quality and quantity of fruit. Symptoms cell walls. They live in the vascular system of are not uniform, and may appear on some or all plants and are spread by sap-feeding insects, shoots of infected vines. A few rootstock including leafhoppers and planthoppers. There varieties are tolerant to flavescence dorée, and are several diseases of grapevine caused by can be symptomless carriers of the disease. phytoplasmas: Leaf symptoms in white cultivars appear as  Flavescence dorée small, yellow spots along the main veins. These  Bois noir (black wood, vergilbungskrankheit) spots enlarge to form yellow bands along the  Grapevine yellows veins, which gradually extend over large parts of Bois noir disease was detected in British Co- the leaf. Red cultivars develop a similar pattern lumbia and Ontario in plants imported from on the leaves, but the discolorations are reddish. France. The plants were removed and subse- Infected shoots often fail to lignify, and appear quent surveys have not detected new infections. thin and rubbery. They later become brittle, Flavescence dorée is the most important and sometimes with bud necrosis. Affected branches destructive phytoplasma disease of grapevines. blacken and die during the winter. Numerous It is known to occur only in France, Italy and small black pustules form along the diseased Spain. Bois noir occurs in France and Germany, branches of susceptible cultivars. but is less serious due to a slower rate of spread. Fruit set is reduced on grapevines infected early Diseases similar to bois noir have also been in the season, as the inflorescences dry out and reported in Switzerland, Italy, Greece, Hungary, fall off. In later infections, bunches become Israel, and are suspected to occur in Chile and brown and shriveled. Premature berry drop South Africa. Phytoplasma diseases of grape occurs in some cultivars. elsewhere in the world are referred to as grape- vine yellows, including an American grapevine Disease Cycle yellows that occurs in New York and Virginia, Flavescence dorée is spread by the leafhopper and an Australian grapevine yellows. Scaphoideus titanus, which is native to eastern Impacts North America. It is known to occur in Canada from the Maritimes through to Saskatchewan, Flavescence dorée has been called “cata- but it has not yet been detected in B.C. strophic” in France. Impacts include reduced vitality of vines, yield reductions, and reduced S. titanus spends its whole life cycle on grape- wine quality due to high acid and low sugar vines. It is a highly mobile and efficient vector contents of fruit from infected plants. Without that is largely responsible for the epidemic control measures, the disease spreads rapidly, spread of flavescence dorée. Both nymphs and affecting up to 80-100% of vines within a few adults are able to acquire the phytoplasma while years. Flavescence dorée has destroyed large feeding. After a latent period they are able to viticultural areas in France and Corsica. It is still transmit the disease until they die. This leafhop- spreading despite mandatory control programs. per overwinters as eggs which are inserted (laid) into the bark of grapevines. Popular cultivars such as Chardonnay, Cabernet Sauvignon, Pinot Noir, Riesling, Sauvignon Bois noir is transmitted by a few planthopper Blanc, and Sémillon are highly susceptible to vectors, the main one being Hyalesthes obsoletus. flavescence dorée. Some cultivars such as This insect is not known to be in Canada. It Sangiovese and Garganega are extremely sus- prefers herbaceous weeds over grapevines and ceptible and are killed quickly. transmits the phytoplasma from these weeds to grapevines. Bindweed (Convulvulus arvensis), nettle (Urtica dioica) and hedge bindweed

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(Calystegia sepium) are the main reservoirs in Note that stricter import requirements for Europe. Since the vector only feeds incidental- grapevines from France and Germany were ly on grape, bois noir is a much slower implemented by the CFIA in 2007 due to spreading disease than flavescence dorée. It is concerns about the increased incidence of widespread in many parts of Europe. The flavescence dorée and bois noir in France. recent identification of new bois noir vectors in Under the new requirements plants and propa- Europe raises concerns regarding related insect gative material originating from, or propagated species in Canada. within, flavescence dorée areas of France, or any Both Phytoplasmas and leafhoppers can be other infested area of a country where the spread with propagation material. Flavescence disease occurs is prohibited. In addition all dorée is symptomless in some cultivars, and it plants or propagative material imported from also has a long (up to 3 year) latent period France or Germany must be treated in a hot before symptoms can be seen. Thus even water bath at a minimum of 50°C for a mini- apparently healthy vines may be carrying grape- mum duration of 35 minutes. Contact the vine yellows diseases. A few rootstock varieties Canadian Food Inspection Agency (CFIA) for are symptomless carriers that have been respon- more information. sible for spread of flavescence dorée in Europe. Grape Root Rot and Decline Control Root diseases caused by Phytophthora or Pythium Control of phytoplasma diseases involves spp. have not been common in the Okanagan/ scouting and removal of infected or symptomat- Similkameen in recent years. These diseases are ic vines, as well as control of the vector with typically sporadic, usually occurring on single insecticide sprays. vines that are excessively irrigated. Affected vines are smaller than nearby healthy plants and In France, flavescence dorée is a regulated the foliage may become chlorotic or colour disease. Compulsory control measures for both prematurely. A canker develops near the soil the disease and the vector were strengthened in line and usually extends downward to the roots. 2003. When an infected grapevine is found, a Removal of the periderm exposes the necrotic quarantine area is delimited around it for a woody tissue underneath. Roots may become minimum of 2 years. All infected plants must be blackened and decayed; and smaller fibrous destroyed, and control of the vector with several roots may die. Death of the vines may occur insecticide sprays is required in that zone. within 2 years from the time symptoms appear. Prevention A root rot caused by the fungus Roesleria subter- Use only planting material from reliable, ap- ranea has also occurred sporadically in Okanagan proved sources and produced in areas where vineyards. It is considered to be a weak root phytoplasma diseases are not present. Canada pathogen that colonizes injured or dead roots, has grapevine import regulations that help to from where it may also invade healthy roots. protect grape growers from the introduction During a 2007/08 survey of grapevine decline and spread of diseases and other pests which are problems, roesleria root rot was found in several not yet established in British Columbia. Selected vineyards in vines that were also infected with grapevine variety and rootstock clones from Cylindrocarpon. Canadian-approved nurseries in France and Control Germany are currently approved for importa- tion into Canada. Under this program, nursery Cultural Control plants are propagated from mother plants that  Prevent root rots with good water manage- were tested for regulated pests and diseases by ment and by providing drainage if needed. the exporting country then grown under condi- Phytophthora and Pythium are “water molds” tions to reduce the risk of contamination. The which are favoured by very wet conditions. CFIA has tested samples of many of these grapevine varieties or rootstocks prior to ap-  In replant sites, remove as many old roots as proving their importation. possible before replanting vineyards.

2010 Best Practices Guide for Grapes for British Columbia Growers 5-19 5 Crop Protection

Chemical Control General Symptoms  There are no fungicides registered for con- General symptoms of grapevine declines caused trol of these soil-borne diseases on grape in by fungal pathogens include delayed and stunted Canada. growth, short internodes, yellowing and prema- ture loss of leaves, tendril dieback, trunk Young Vine Decline dieback, dead arm and cankers. Discolouration may be observed in the wood when vines are Decline of young vines may have several causes, cut open. Decline may be rapid, causing plant including diseases, nematodes, environmental death within 2-3 weeks, or slow, resulting in damage such as winter injury, and cultural reduced vigour and yield over a period of years. factors. Often more than one factor or more than one disease may be involved. Diagnosis Okanagan Survey Results (2007-2009) Vine decline symptoms can be difficult to diagnose accurately. B.C. grape growers inter- A recent survey conducted by Agriculture and ested in diagnosis of decline problems should Agri-Food Canada investigated decline prob- contact the provincial plant diagnostic laborato- lems in Okanagan vineyards (O'Gorman, Haag ry or PARC Summerland for more information. & Sholberg). The survey confirmed the pres- ence of several fungal pathogens causing vine Further Information decline symptoms. Diseases detected included: For links to further information, visit the Ministry of Agriculture and Lands website at  Black foot disease (Cylindrocarpon spp.) - http://www.al.gov.bc.ca/cropprot/grapeipm/ isolated from vines ranging from 3-15 years decline.htm of age in several vineyards. Infection was associated with both a gradual and a rapid Esca / Young Vine Decline decline of vines. Young Vine Decline is a disease complex with  Esca (Phaeomoniella chlamydospora and Phaeo- various names, including black measles, esca, acremonium aleophilum) - detected in necrotic young esca, Petri disease, apoplexy, and black vascular tissue on young vines up to 6 years goo disease. It has been an increasing problem old. Both Phaeoacremonium and Cylindrocarpon in California vineyards, causing significant were recovered from vines in one vineyard economic losses due to vineyard replanting and where over 50% of the vines showed decline yield reductions. It has also increased in im- symptoms. portance in Europe, most likely due to a  Botryosphaeria canker (Botryosphaeria parva reduction in the use of sodium arsenite fungi- and B. dothidea) - detected in vines ranging cides, which have been banned in most from 3-11 years of age in several vineyards. countries. The vineyards where B. parva was isolated In California, esca or black measles has been a showed severe decline problems. problem in older vineyards for decades. More recently it has also become a problem in young  Eutypa canker vines, following a massive replanting effort  Roesleria root rot (Roesleria subterainia) - which replaced phylloxera-susceptible root- found in several vineyards in vines that were stocks with other more resistant hybrid also infected with Cylindrocarpon. rootstocks. Unfortunately, the new rootstocks appear to be more susceptible to vine decline. Note that black foot, esca, botryosphaeria canker and eutypa canker are all new diseases A 2007-2008 survey conducted by Agriculture that have not been previously diagnosed in and Agri-Food Canada investigated decline British Columbia vineyards. See below for more problems in Okanagan vineyards (O'Gorman, details on each of these pathogens. Haag & Sholberg). The survey confirmed the presence of several fungal pathogens causing vine decline symptoms, including 2 pathogens associated with esca. 5-20 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection

Causal Agents observed on terminal leaves followed by shoot tip dieback. It is thought that foliar symptoms Esca and young vine decline are caused by are caused at least partially by toxins produced several fungi which act alone, in combination by the fungi and/or reaction products of the or in succession to cause disease. Fungal infected wood which are translocated to the pathogens involved in young vine decline in leaves. both British Columbia and California include Phaeomoniella chlamydospora and Phaeoacremonium Symptoms on berries may be present without aleophilum. Other species of Phaeoacremonium symptoms on the leaves and vice versa. Berries have also been associated with esca vine on affected plants tend to be small, and may not decline in California, but have not yet been reach full maturity. Sugar content and flavour detected in B.C. can be adversely affected. Berries sometimes develop spotting or black measles symptoms, Several wood rotting basidiomycete fungi with white cultivars being more susceptible. including a Phellinus species (now known as Berry spotting consists of brownish to purplish, Fomitiporia punctatus) and Stereum hirsutum were small pinprick sized spots on the berry skin. historically associated with esca. While these Heavy spotting may lead to skin cracking, berry fungi could be isolated from diseased vines, it shrivel, and secondary berry rots. was not possible to reproduce the same symp- toms by inoculating healthy vines. It is now Symptoms - Esca / Black Measles thought that infection with Phaeoacremonium and on Older Vines Phaeomoniella species predisposes the vines to wood rots by breaking down toxic phenolics Esca is known as a disease of adult plants (8-10 and other host-produced substances which are years and older). It is caused by the same fungi inhibitory to wood rot fungi. that cause young vine decline. However on older vines there are often wood rot pathogens There are also several other diseases which involved as well. Symptoms are similar to those cause decline of grapevines including Cylindro- described on young vines. It causes a decline carpon black foot, Botryosphaeria canker, Eutypa, with characteristic leaf and fruit symptoms, and Phomopsis canker (not yet found in B.C.) and sudden wilting and death in severe cases. several root rot diseases. Additional symptoms in older wood include an Symptoms - Esca on Young Vines internal white heart rot which causes the wood Phaeomoniella and Phaeoacremonium infect the to become soft and spongy. A dark line or a vascular tissue of young vines resulting in series of black dots generally surrounds the darkening and plugging of the xylem vessels. white heart rot. In longitudinal section, this Symptoms range from mild to severe, and vascular discolouration appears as black streaks. include chlorotic foliage, defoliation, stunting of Disease Cycle growth and reduced yield and quality. Sudden wilting and death (apoplexy) of vines or cordons Research underway in California is increasing may occur in midseason, particularly during hot our understanding of the biology of the fungi weather. Vine symptoms also include delayed causing young vine decline. The method of and weak growth in spring, and reduced lignifi- disease spread is not yet certain, however spore cation of canes in the fall. Discolouration in the trapping results from infected vineyards have xylem vessels may appear as black streaks when found air-borne spores, with large numbers of vines are cut longitudinally or as black dots spores trapped during rainfall. Infection most when cut in cross section. Wood rot is usually likely occurs through wounds. absent on young vines. Wet weather and warm temperatures appear to Foliar symptoms include light green or chlorotic favour the disease. Years with above normal spots between the leaf veins or along the leaf rainfall and high summer temperatures have margins. The spots gradually expand and turn resulted in more severe symptoms in California. yellow brown or red brown, leaving only a The wood rot fungi that are associated with esca narrow strip of green tissue along the main are wound invaders, which infect through large veins. In California, a mosaic has also been 2010 Best Practices Guide for Grapes for British Columbia Growers 5-21 5 Crop Protection wounds or pruning cuts on the trunk or cor- disease had not been previously diagnosed in dons of mature vines. These fungi have a wide grapevine from British Columbia. host range, and are commonly found as wood Bot canker is known to occur in most viticulture rots in other broad leaf tree species. Air-borne regions of the world. In California, recent basidiospores produced by fruiting bodies research has shown that over 9 species of (bracket fungi) on dead wood or other hosts can Botryosphaeria can infect grapevines, and that the be spread long distances by wind, and can infect disease is very prevalent in that state. The grapevines. Observed spread along rows in following information is based on information vineyards may also indicate that spores can be from California and other viticultural areas. spread by tools during pruning and grafting. Dissemination in Nursery Stock: The pres- Symptoms ence of vine decline affecting a high proportion Botryosphaeria produces black streaks in the of plants in recently established vineyards in xylem of infected wood, typically causing California suggests that nursery stock may be wedge-shaped cankers in the trunk and cordons. carrying the disease. The pathogens have also The cankers are most easily seen when the vine been isolated from a high proportion of vine is cut in cross section. Black pycnidia (fungal cuttings produced in Italy or France. fruiting bodies) form on diseased vine parts under the bark of cordons, trunks, and spurs. Prevention and Management Other diseases, including Eutypa canker cause  Plant healthy vines with no sign of very similar symptoms. discolouration in the vascular tissue. In California, botryosphaeria canker causes  Propagation material should be taken from death of arms, cordons and vines, often so healthy vines with no wood darkening. suddenly that there are no foliar symptoms. It is commonly seen in vines 10 or more years old.  Burn prunings, or remove them from the In other areas, foliar symptoms such as chloro- vineyard. sis and stunting are more common. Symptoms  Prune healthy-looking vines before sick may vary depending on the species of Botry- vines. Disinfect pruning tools periodically, osphaeria present. Typically diseased vines fail to particularly after pruning vines with symp- break dormancy or suddenly wilt during the toms. following growing season. Disease Cycle  The type of vine training system can be a factor. Extensive pruning cuts create more The fungus overwinters as pycnidia on diseased potential infection sites. One study found wood. Pycnidia release conidia (spores) when 0.1% esca in lateral cordon vineyards, com- wet by rain or irrigation. Conidia are spread by pared to 15-20% in vines trained by double water splash and wind to cause new infections, Guyot. primarily through fresh pruning wounds. Mois- ture is needed for infection, along with  There are no fungicide treatments for esca/ temperatures above 5 ° C. young vine decline in Canada. Botryosphaeria can also infect other tree species, Botryosphaeria Canker and could also be present in adjacent orchards, forests and riparian areas. The importance of A survey of grape decline problems in Okana- spread from other host species to vineyards is gan vineyards was conducted in 2007/08 by not well understood. Agriculture and Agri-Food Canada (O'Gorman, Haag & Sholberg). Botryosphaeria canker (also Disease Prevention & Management known as bot canker and black dead arm) was detected in vines ranging from 3-11 years of age  Remove visible cankers and dead or declin- in several vineyards. Two species of Botryto- ing arms, cordons and vines. sphaeria were identified, including B. parva and B.  Burn prunings from infected vines, or dothidea. The vineyards where B. parva was remove them from the vineyard. isolated showed severe decline problems. This 5-22 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection

 Prune healthy-looking vines before sick survives in soil as mycelium and also produces vines. Disinfect pruning tools periodically, conidia (spores) and chlamydospores (spores particularly after pruning vines with symp- that can survive adverse conditions). toms. Research in South Africa has shown that nurse-  In California, late pruning during March ry soils can be a source of inoculum, and the results in less infection of pruning wounds. disease can be carried on nursery plants. Optimal timing may be different in our cli- Disease Prevention & Management mate. In general, warmer temperatures accelerate healing of pruning wounds, so  Plant healthy vines with no sign of root wounds are susceptible for a shorter time. deterioration or discolouration in the vascu- Pruning during a period of forecast dry lar tissue. weather would also help to reduce infection.  Hot water treatment has been shown in  Good cultural practices help to maintain South Africa to reduce the level of Cylindro- vigour and reduce losses. carpon infection in nursery stock. Hot water treatment at a similar temperature and dura-  There are no fungicide treatments for Botry- tion is required for vines imported from osphaeria canker available in Canada. France or Germany for the prevention of Black Foot Disease phytoplasma diseases. (Cylindrocarpon spp.)  There are no fungicide treatments for Cylindrocarpon available in Canada. A survey of grape decline problems in Okana- gan vineyards was conducted in 2007/08 by Agriculture and Agri-Food Canada (O'Gorman, Grape Nematode Problems Haag & Sholberg). The causal agent of black Nematodes are translucent, microscopic foot disease (Cylindrocarpon spp.) was isolated roundworms, typically measuring 0.25 to 1 mm from vines ranging from 3-15 years of age in in length and only about 0.1 to 0.2 mm in several vineyards. Infection was associated with diameter. Most nematodes in soil are beneficial both a gradual and a rapid decline of vines. This components of the soil ecosystem, where they disease had not been previously diagnosed in feed on bacteria, fungi and other micro- grapevine from British Columbia. invertebrates, stimulating and regulating the Cylindrocarpon is known to occur in all major turnover of nutrients. Their abundance ranges viticulture regions of the world, but the disease from about 1000 per liter of degraded or infer- is not well understood. It's importance in B.C.'s tile soil, up to 50,000 per liter of highly fertile vineyards remains to be seen. The following soil. Some nematode species, however, parasi- information is based on information from tize plant roots and are economically important California and other viticultural areas. plant pathogens. Symptoms Symptoms In California, Cylindrocarpon causes "black foot All plant-parasitic nematodes use hollow spear- disease" in grape, affecting mainly young vines like mouthparts called “stylets” to feed on plant up to 8 years old. Roots show black, sunken, roots. A few nematode species do not cause necrotic lesions. In cross section, the base of the much direct damage on their own, but can trunk appears necrotic and xylem vessels may be transmit viruses while they are feeding (see black in colour. Leaves may appear to be water section on dagger nematodes, below). Most stressed or scorched, and vines may be stunted species cause direct damage, including gall-like and/or killed. Cylindrocarpon may occur in malformations that impair root function (see combination with other plant pathogens. root-knot nematodes, below) or dieback of root tips and formation of lesions on the roots (see Disease Cycle ring nematodes and root-lesion nematodes, Cylindrocarpon is a common soil-borne fungus below). When nematode population densities which causes root rot in many plant species. It are large, root systems will be sparse, there will 2010 Best Practices Guide for Grapes for British Columbia Growers 5-23 5 Crop Protection be few fine roots, and the damaged roots will recently been found to be relatively widespread appear reddish, brown or black rather than a in the Okanagan Valley, and preliminary re- healthy white colour. If root-knot nematodes search at the Summerland Research Centre are present, it may be possible to see character- indicates that they can cause significant growth istic swellings or galls on feeder roots. Vines reduction of young grapevines, particularly self- severely damaged by plant-parasitic nematodes rooted vines, under Okanagan growing condi- are stunted and have reduced yields. tions. At the field level, nematode damage is often Root-knot nematodes (Meloidogyne overlooked because the above-ground symp- hapla): These nematodes are endoparasites; toms are non-specific and difficult to distinguish infective juveniles invade root tips and establish from effects of other factors. Nematode popu- permanent feeding sites. As the nematodes feed lations usually exist in patches of high and mature in the root, galls or “knots” of root population densities; rarely, entire fields will be tissue form around them. These galls, which uniformly affected. Thus typical symptoms typically range in size from 3 to 12 mm in include poor vine vigour in patches of one to diameter, interfere with water and nutrient dozens of vines. This patchy, uneven growth uptake. Several species of root-knot nematodes caused by plant-parasitic nematodes may occur are recognized to be significant pests of grape in within a vineyard with uniform soil conditions. most grape-growing regions. To date, only one Areas with high nematode population densities species has been found in B.C. vineyards, may also be correlated with other soil factors Meloidogyne hapla. The damage caused by M. that can affect vine vigour. For example, many hapla has not been studied as extensively as species of plant-parasitic nematodes reach other species, and its impact on grapevine higher populations and cause more damage in health under Okanagan growing conditions is sandy soils than in finer-textured soils. As a not clear. result, poor vine growth in sandy soils can be the result of low water or nutrient availability as Dagger nematodes (Xiphinema species): well as the interaction of these additional stress- Xiphinema americanum and several closely related es with nematode damage. species of Xiphinema are commonly found in B.C. vineyards. These nematodes are ectopara- Nematode Species sites; they do not burrow into roots, but insert their long stylets deep into root tips, where they The main nematode species of significance to feed on root tip cells. Dagger nematode feeding winegrape production in British Columbia are causes limited necrosis and stunting and swell- ring nematodes (Mesocriconema xenoplax), dagger ing of root tips, but they seldom cause nematodes (Xiphinema species), root-knot significant damage on their own. Dagger nema- nematodes (Meloidogyne hapla) and root-lesion todes are mostly important as vectors of viruses; nematodes (Pratylenchus penetrans). Vineyards in X. americanum and related species transmit British Columbia often have more than one Tomato ringspot virus, Tobacco ringspot virus, Peach species. rosette mosaic virus and several other minor virus- Ring nematodes (Mesocriconema xeno- es. plax): These nematodes are ectoparasites that Xiphinema index transmits the devastating Grape- use long stylets to extract the contents of root vine fanleaf virus. This nematode species can also cells, especially at root tips. They cause necrosis cause significant direct damage in the absence of or blackening of roots like root-lesion nema- the virus. Plant protection measures that require todes, but their preferential feeding at root tips treatment of imported planting stock have also causes stunting and sometimes formation prevented Xiphinema index from being intro- of swollen or malformed root tips without duced into British Columbia. obvious necrosis. Preferred hosts for ring nematodes include cherry, peach, apricot, and plum in addition to grape. These nematodes are known to cause significant damage to grape in California and Oregon. Ring nematodes have

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Root-lesion nematodes (Pratylenchus well prepared before fumigation, and should be species): These nematodes are migratory moist. As many old grape roots should be endoparasites, burrowing into roots to feed, and removed as possible. These products release migrating freely between root tissue and soil. toxic gases on contact with moist soil. Follow- Root-lesion nematodes cause symptoms that ing application, the soil surface should be sealed range from many small lesions on young feeder by watering and rolling or with polyethylene roots to abnormal darkening and necrosis or sheets. Refer to the product labels for detailed death of the roots. Severely damaged root information on application and safety precau- systems will have few newly formed feeder tions. roots and sparse tufts of fine roots that will be Soil fumigation is expensive. Before consider- blackened and crumbly. Most research docu- ing, have samples of your soil analyzed for menting impacts of root-lesion nematodes has nematodes. been conducted on Pratylenchus vulnus, a species that does not occur in B.C. The species most Alternatives to fumigation commonly found in the Okanagan Valley is P. Soil solarization is a non-chemical technique penetrans. While this nematode clearly damages that will help to reduce the population of roots, the relationship between P. penetrans nematodes and other soil-borne pests. Solariza- population densities and overall vine vigour is tion involves capturing the heat of the sun by not well understood. covering the soil with transparent polyethylene Nematode Resistant Rootstocks plastic sheets during warm sunny months. The soil temperatures under the plastic increase to Rootstocks that are tolerant or resistant to levels lethal to many soil-borne plant pathogens, plant-parasitic nematodes are available. These weed seeds, seedlings, and nematodes. It is rootstocks have been evaluated against nema- usually necessary to take the land to be solarized tode species found in California and out of production for a year. Soil should be Mediterranean regions of Europe. Consequent- tilled before solarization, and should also have a ly, it is not clear if they would express the same good soil moisture level. The area to be treated tolerance or resistance to nematode species should be free of weeds, plant debris, and large found in B.C. Rootstocks reported to be clods which would raise the plastic off the tolerant or resistant include: Dogridge, Harmo- ground. Cover the area with a double layer of ny, Freedom, Ramsey, Teleki 5C, K51-32, and clear polyethylene sheet, seal the edges with soil 1613C. Two other rootstocks, 420A Mgt and and leave it in place for 4-6 weeks during the 101-14 Mgt, are reported to be resistant to ring heat of the summer (mid-June through mid- nematodes, which are overall probably the most August). If possible, leave the poly in place until important nematodes in B.C. vineyards. replanting to prevent re-contamination. Black Prevention and Control plastic is less effective than clear plastic. Nematodes are best managed before planting. Other cultural management techniques include Prevention involves testing for the presence of green manuring, and/or rotating crops to pathogenic nematodes followed by pre-plant reduce the numbers of pathogenic nematodes. soil fumigation to reduce nematode populations. These tactics do not guarantee a reduction in There are no chemical treatments for nema- nematodes, as populations may be sustained on todes that can be used on established vines in other species of plants including weeds. Canada. Nematode Testing Pre-plant Soil Fumigation Consider testing your soil for plant-parasitic Soil fumigation with chemicals such as Vapam nematodes before planting new vineyard blocks. (metam-sodium) and Basamid (dazomet) are an If damaging populations are present, consider option for reducing the population of pathogen- soil fumigation before planting. ic nematodes in soil prior to planting. They will Sampling strategies and interpretation of the also help to reduce the levels of soil-borne plant results depend on the nematode species sus- pathogens and viable weed seeds. Soil must be pected and environmental conditions, and 2010 Best Practices Guide for Grapes for British Columbia Growers 5-25 5 Crop Protection should be developed in consultation with a Other Grape Diseases diagnostic laboratory. Populations of all nema- tode species vary seasonally. Since some There are many grapevine pests and diseases nematode species migrate between roots and that are not yet established in British Columbia soil, it is usually necessary to collect both soil grape growing areas. Some of these are downy and root samples for testing. The laboratory mildew, black rot, phomopsis, flavescence analysis includes extraction of nematodes from dorée, Pierces’ disease, anthracnose, rust and soil and plant tissue, identification of the species dead arm. present, and enumeration. The absence of If you suspect a new disease, contact the BC recognized nematode pathogens in diagnostic Ministry of Agriculture and Lands to confirm samples can be used to rule-out nematodes as identification, or send a sample to the provincial the cause of poor crop growth. Plant Diagnostic Laboratory in Abbotsford. Soil analysis for the presence of nematodes is Plant Diagnostic Lab provided by the following laboratories. Contact BC Ministry of Agriculture and Lands the labs directly for information on fees and Abbotsford Agriculture Centre, sampling instructions: 1767 Angus Campbell Road, M&B Research Ltd. Abbotsford BC V3G 2M3 10115C McDonald Park Road Tel: 604-556-3126 (directly) or 1-800-661-9903 Sidney, BC V8L 5X5 (main office) Fax: 604-556-3154 Tel: 250-656-1334 Fax: 250-676-0443 Web: www.al.gov.bc.ca/cropprot/lab.htm BC Ministry of Agriculture and Lands Online resources for Grape Disease Plant Diagnostic Laboratory Information: Abbotsford Agriculture Centre 1767 Angus Campbell Road  BC Ministry of Agriculture – Grape Diseases Abbotsford, BC V3G 2M3 www.al.gov.bc.ca/cropprot/grapeipm/index. Tel: 604-556-3126 (directly) Fax: 604-556-3154 htm Toll Free: 1-800-661-9903  InfoBasket - http://www.kmwpp.ca/ http://www.al.gov.bc.ca/cropprot/lab.htm  UC IPM Pest Management Guidelines - University of California www.ipm.ucdavis.edu/PMG/selectnewpest. grapes.html  Northwest Berry and Grape Information Network - Oregon State University http://berrygrape.org/  Grape and Small Fruit Virology -Washington State University - wine.wsu.edu/virology/

5-26 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection

5.3 Insect & Mite Pests of Grape D. Thomas Lowery, AAFC-PARC, Summerland Healthy populations of predators and parasites (Graphics by Robyn DeYoung) prevent outbreaks of secondary pests and reduce the numbers of sprays required for the Fewer insect pests attack grapes grown in control of primary pests such as leafhoppers British Columbia compared with most other and climbing cutworm. major grape producing regions. For this reason, growers in British Columbia are able to pursue Beneficial organisms can be preserved or ‘soft’ programs that preserve populations of enhanced in several ways. The negative impact beneficial insects and predacious mites that help of pesticides can be minimized by spraying only control secondary pests such as spider mites and when and where required. Monitoring of pest thrips. Adoption of integrated pest manage- numbers will often indicate that only a small ment (IPM) practices that minimize the use portion of a vineyard requires chemical treat- of chemical sprays can also help lower ment, while selecting the most appropriate spray production costs, reduce human exposure material will help reduce damage to non-target to insecticides, and preserve the local envi- organisms. Broad spectrum insecticides such as ronment. Additional sources for information the pyrethroids, for example, act on contact and on insect and mite pests of grapes are listed at by inhalation and are often more toxic to the end of this section. beneficial insects than the pests they are intend- ed to control. Some organophosphates, such as Integrated Pest Management malathion, also act primarily on insects as a IPM utilizes a number of principles and practic- contact and fumigant, but they are considered to es to manage pest populations, including be less damaging to beneficial insects and mites. biological, cultural, and physical control meth- Other materials, such as the microbial insecti- ods. Insecticides remain an essential cide Dipel (B.t.), are highly selective and require component of an IPM program, but they are that the pest consumes the treated plant part, applied as a last resort only when monitor- reducing toxicity to most non-target species. ing has shown that pest numbers are likely Refer to the fact sheet Pest Control Products to exceed the economic threshold. When Recommended for Use on Grapes in British Columbia, insecticides are required, their selectivity, persis- posted at tence, and effects on non-target organisms http://www.al.gov.bc.ca/cropprot/grapeipm/ should be considered. Some have minimal grape_pesticides.pdf for additional information. effects on beneficial insects and predacious Thoughtful choice of management practices can mites, while others cause significant reductions also help preserve beneficial insects. Mowing or in natural enemy populations. A brief descrip- discing less often is a simple and cost effective tion and a few examples of the various way to increase populations of most natural components of a grape IPM program are enemies. Adults of many beneficial species feed outlined below. For additional information, on nectar of flowering plants that also serve as refer to the Integrated Pest Management section hosts for alternate prey species. As a general of this guide. rule, increased plant diversity is associated with Biological Control of Insects greater numbers of beneficial insects. A diversi- ty of plants can be provided in the vineyard in and Mites mixed ground covers, or in hedgerows and Insect and mite pests of grapes are attacked by waste areas within or adjacent to the vineyard. many species of beneficial organisms, including bacterial and viral diseases, spiders and insect predators, predacious mites, and vertebrates such as toads and birds. Maintaining and enhancing numbers of these natural ene- mies of grape pests forms the cornerstone of a successful IPM program. 2010 Best Practices Guide for Grapes for British Columbia Growers 5-27 5 Crop Protection

Cultural and Physical Pruning Controls Pruning can be altered to help reduce damage Vine Vigour and Resistance from cutworm larvae. Slightly more buds can be left on vines to compensate for damage, but this For most crops, varieties can be selected that will require the removal of unwanted shoots are partially or wholly resistant to one or more later in the season. Earlier pruning advances pests and diseases. Except for rootstocks that bud break, reducing slightly the amount of time are resistant to grape phylloxera or nematodes, that buds are susceptible to cutworm feeding. this is generally not a viable option for wine Vines that break bud earlier are more suscepti- grapes. Most desirable wine grape varieties ble to frost damage, however. To reduce possess little resistance to foliar feeding pests. damage from spring-feeding pests, some grow- Vine vigour does, however, influence insect and ers delay suckering and shoot thinning to divert mite numbers. Leafhoppers and grape mealy- feeding to these unwanted plant parts. bug, for example, will reach significantly higher numbers on overly vigorous vines, as they Leafhoppers and erineum or blister mites infest prefer the darker, sheltered environment and the first leaves that emerge in spring and these elevated humidity that excessive vine growth can be removed in June to reduce numbers of provides. Insects developing on these plants these pests. A recently completed study con- survive better and grow faster due to better ducted in commercial British Columbia nutrition, softer tissues, and changes in concen- vineyards showed that removal of basal leaves trations of secondary plant compounds. At the in June rather than August reduced numbers of other extreme, chlorotic vines with low vigour leafhoppers and the incidence of bunch rot. are less able to tolerate insect feeding damage Vine vigour and berry size were reduced only and are more susceptible to attack by scale slightly and there was little effect on ripening or insects and wood boring beetles. Fortunately, quality of fruit. Early season leaf removal might the optimum balance in vine growth that not be suitable for stressed vines or vines on results in the highest quality wines is also sandy sites with intense heat and light where best for minimizing the growth of pest fruit can become sunburned. As for late season populations. removal, partial removal of leaves from only the Management of vine vigour is an important shaded sides of the vines might be more suitable consideration in the establishment of a new in these areas. vineyard and is discussed elsewhere in this Physical controls guide. After vines are established, growth is controlled mainly by pruning, cropping, selec- For some vineyards, the use of yellow sticky tion and management of appropriate ground- tape applied below the cordon in spring can be cover plants, and the provision of water and an economical way to manage leafhoppers. nutrients. Recent research in California has Although costly, this physical control method shown that deficit irrigation from berry set to preserves beneficial insects and reduces or veraison reduced leafhopper numbers by more eliminates the need for additional insecticides than 60%. The modest reduction in yield, later in the season. Use of yellow sticky tape is around 15%, was more than offset by a signifi- most practical in vineyards where damaging cant improvement in wine quality. In addition, numbers of leafhoppers occur in small, isolated berries were smaller and exposed to more light areas or on a few outer rows of the vineyard. and air and pruning costs were slightly lower. Other physical controls include pruning out of canes infested with scale insects and application The presence of broadleaf weeds in and be- of barriers to prevent climbing cutworm from tween vine rows is associated with lower levels reaching developing buds. of cutworm damage. Where possible weeds should not be controlled in spring until after buds have broken, as removal of alternate sources of food forces cutworm larvae to feed on the buds of grapes. 5-28 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection

Monitoring and Chemical Controls usually after the middle of August. Throughout summer, monitor for mealybug, thrips, and Insecticides should only be applied when mites. For table grapes, watch for mealybug monitoring indicates that sprays are warranted. infesting clusters in mid-summer and for snail- The mere presence of a pest does not indi- case bagworm and earwigs closer to harvest. cate that a spray is required. Established If chemical control of a pest is indicated, refer grapevines can tolerate moderate amounts of to the BCMAL fact sheet Pest Control Products leaf damage and small numbers of pests may Recommended for Use on Grapes in British Columbia, have little or no effect on vine growth and for suitable spray materials, or consult with yields. Some studies have actually shown that private consultants or your chemical supplier. It low numbers of some pests can stimulate vine is the legal responsibility of pesticide appli- growth and improve fruit quality. Even when cators to follow the label instructions and pests have reached damaging levels sprays apply only those products that are registered should be withheld until the economic benefit for use on grapes. The BC Wine Grape of treating the crop exceeds the cost of control- Council and the authors of these pest man- ling the pest, including possible disruption of agement sections do not assume legal beneficial insects. In other words, sprays responsibility for the misuse of any pesti- should only be applied when pest popula- cides mentioned in this guide. For grapes or tions reach the economic injury level where wines destined for export, check to ensure that control of the pest provides an economic the importing country has maximum residue return to the grower. levels (MRL) for the control products. Observe Thresholds for grape pests are currently based the days to harvest interval (PHI = pre-harvest mostly on visual inspections. Yellow sticky cards interval) to avoid exceeding the MRL. Produc- can be useful indicators of general population ers of organic grapes should also refer to the list trends and pest developmental stages. Care of acceptable products and consult with an should be taken to conduct a thorough inspec- organic growers’ organization. tion that takes into account the variable nature of the crop and the uneven distribution of most Major Pests of Grape grape pests. Particular attention should be given The major insect and mite pests of grapes to field edges and to areas that have experienced grown in British Columbia are cutworm larvae damage previously. The use of double sided that attack buds in spring, leafhoppers that feed clear tape applied around shoots or the vine on leaves throughout the summer, and wasps cordon can be used to assist with timing of that feed on ripening fruit in fall. Grape phyl- sprays for the control of motile stages of grape loxera is an important pest of grapes worldwide mealybug and scale insects. but it occurs in only a few scattered locations in Grapevines need to be monitored for pests the southern interior of British Columbia Other throughout most of the year. It is easier to spot than wasps, these pests are largely absent from scale infestations during pruning or early in the Lower Mainland and Vancouver Island. spring before leaves are present. Grapes need to Proper management of these primary pests is be visually inspected frequently in spring when the most important consideration in an IPM unopened buds are susceptible to cutworm program. Grape pests and the damage they damage. When the first leaves have fully ex- cause needs to be recognized so that popula- panded, watch for early infestations of erineum tions can be monitored at the appropriate time mite and note the presence of leafhopper adults of the season to determine if insecticide applica- that begin laying eggs at this time. Thrips tions are warranted. Avoiding unnecessary damage table grapes from 75% bloom to fruit sprays will help prevent outbreaks of secondary set, and if scale or mealybugs were noted earlier, pests that are normally regulated by an assort- sprays can be timed based on the presence of ment of predators and parasites. crawlers. The need to spray for first generation leafhoppers should be based on monitoring for small nymphs from mid June to mid July, while second generation nymphs will reach their peak 2010 Best Practices Guide for Grapes for British Columbia Growers 5-29 5 Crop Protection

Leafhoppers pale yellowish body colour. Larger VCLH (Virginia creeper leafhopper, Erythroneura ziczac Walsh) nymphs develop a pair of dark reddish-brown (Western grape leafhopper, E. elegantula Osborn) spots on the first body segment behind the head and a pair of reddish-orange spots on the other In addition to the widespread Virginia creeper two thoracic segments. Nymphs can be identi- leafhopper (VCLH), the western grape leafhop- fied feeding on the undersides of fully expanded per (WGLH) occurs on the east side of the leaves that show signs of feeding damage Okanagan Valley from the north end of Pentic- (stippling). ton south to the U.S. border. The WGLH is more tolerant to insecticides and it is important to determine if it is present in your vineyard. Leafhoppers are often distributed unevenly in vineyards and monitoring will help determine which areas require treatment. Unnecessary sprays reduce numbers of beneficial insects and spiders, resulting in a rapid resurgence in pest numbers and outbreaks of thrips, mites, and mealybugs. Experience has shown that WGLH

numbers are low in organic vineyards; damag- ing populations in conventional vineyards generally result from repeated sprays of insecti- cides that do not control this species but damage numbers of the egg parasite, Anagrus erythroneurae. Successful control of leafhoppers relies on proper monitoring of numbers throughout the vineyard and the judicious use of insecticides in order to preserve beneficial insects and spiders. Identification Adults of both species are similar in appearance, nearly ½ cm in length with reddish-brown Life Cycle and Damage markings on a pale white or yellowish back- ground. Adult WGLH can be distinguished by The biology and life cycles of the two species their pale eyes and irregular reddish-orange are similar. There are two generations each year. markings on a whitish background. VCLH have Adults of both species spend the winter in leaf reddish-brown eyes and a more regular reddish- litter or under plant debris in the vineyard or in brown zigzag pattern on the wings. The back- nearby vegetation. Adults emerge on warm ground body colour is pale yellow to light spring days to feed on a wide variety of plants, brownish-yellow, producing an overall darker moving to grape, Virginia creeper and Boston appearance. Adult leafhoppers are best identi- ivy when the first leaves appear. The overwin- fied on yellow sticky cards placed in outer tered females deposit eggs in the leaf tissue on vineyard rows during late April and May that the undersides of fully expanded leaves during can be inspected with the aid of a hand lens or May and June. The small, flattened opaque eggs magnifying glass. are deposited side by side, usually in small groups of around two to six for the VCLH and Immature stages (nymphs) of WGLH are singly for the WGLH. Nymphs of this 1st distinguished by their pale white colour, lack of generation hatch mainly from mid June to the pigmentation in the eyes, and the presence of end of July. There are five nymphal stages. one to three pairs of pale indistinct yellow spots Winged adults that appear during July and on the thoracic segments of larger nymphs. August lay eggs that develop throughout the fall VCLH nymphs have reddish-brown eyes and a into overwintering adults. The WGLH develops

5-30 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection more slowly than the VCLH and nymphs will average number of nymphs per leaf. occur later into the year. Established grapevines are tolerant of leafhop- Both adults and nymphs feed by piercing per damage during the first half of the season individual leaf cells and sucking out the con- when growth is rapid. Because of this, there are tents. Light infestations cause leaves to appear no established thresholds for 1st generation stippled due to the death of individual cells. nymphs. The threshold of approximately 20-25 Heavier feeding results in brown, dried leaves nymphs per leaf established for the 2nd genera- that fall prematurely. Some studies have shown tion in late summer can also be used as an that light infestations can actually improve the approximate threshold for early summer sprays. quality of grapes on vines that are overly vigor- A higher threshold can be used for 1st genera- ous, but excessive feeding reduces the tion nymphs if healthy populations of predators photosynthetic activity of the vines, resulting in are present and a high rate of parasitism is likely. delayed maturity, yield losses, and reduced fruit Control of 1st generation nymphs is often more quality. Large infestations deplete carbohydrate effective as there is less foliage, nymphs are stores and weaken the vines. Light coloured confined to leaves around the fruiting zone, and varieties can become spotted and unsightly with sprays can be directed in a narrow band to excrement, which is a particular concern for ensure good coverage. It is recommended, table grapes. Adult leafhoppers are also an therefore, to treat vineyards with a history of annoyance to pickers during harvest. Neither heavy leafhopper damage during this time. Soap species is known to transmit viruses or other sprays are much more effective when targeted plant diseases. against 1st generation nymphs when approxi- mately 80% of the eggs have hatched. Egg hatch Monitoring and Spray Thresholds can only be determined with the aid of a low Overwintered adults usually congregate in power microscope, but the presence of mostly higher numbers on the edges of vineyards or in small, young nymphs can be used as an approx- sheltered locations and these areas should imate measure. Because soaps are not as receive particular attention in the spring. Leaf- effective as other insecticides, the threshold for hoppers also prefer vigorous vines and those vineyards that are managed organically should that leaf out earliest. Monitoring numbers of be reduced considerably, perhaps to around 5- adults captured in spring on yellow sticky cards 10 nymphs per leaf. can help determine relative infestation levels, Second generation nymphs should be moni- but because some eggs fail to develop and tored beginning in August in a manner similar predation rates are variable, these numbers do to that outlined above. Greater attention should not correlate well with subsequent nymph be paid to vines in the center of the field, counts. It is helpful to note where large num- however, as infestations will have spread from bers of adults occur early in the season, as these field edges and ‘hot spots’ to a larger area of the areas should be observed more closely later on. vineyard. Nymph counts should be collected Adults are more tolerant of insecticides and initially every other week, and then weekly when sprays should be targeted against the wingless the time for spraying approaches. For wine immature stages. Depending on the location of grapes, an approximate threshold of 20-25 the vineyard, monitoring of 1st generation nymphs/leaf on the more heavily infested nymphs should begin in early to mid June. leaves can be used as a rough guideline. Monitor populations by counting numbers of This is an average value based on counts from nymphs on the lower surfaces of 5-10 leaves in several leaves as outlined above. Again, for a at least 5 locations per block or variety. Select particular area of the vineyard, collect at least 5 older bottom leaves up to just above the fruiting leaves from 5 areas and calculate the average zone. In order to prevent damage to any vines, number of nymphs per leaf. For 2nd generation sampling should focus on more heavily infested nymphs, sample leaves from the middle of the areas. Sample from the north and east sides of canopy above the fruiting zone and from the rows where more nymphs will be found and north or east sides of vines where numbers will focus on the leaf zone showing signs of feeding be higher. Leafhoppers will be distributed damage. Infestation levels are based on the unevenly in a vineyard and it is important to 2010 Best Practices Guide for Grapes for British Columbia Growers 5-31 5 Crop Protection sample thoroughly to determine which areas berry size, but it is recommended that growers require treatment. Although the above threshold first assess the effectiveness of early leaf remov- provides a rough guideline, an acceptable spray al on only a few vines of each variety. Removal threshold should be determined by individual of leaves around the fruiting zone at any time of growers based on their past experience and the season might not be suitable for stressed additional factors such as vine vigour and vines or on sites with intense heat and light that numbers of beneficial insects. might lead to sunburn. This practice is labour intensive, but growers often remove these Biological Control leaves later in the season in order to improve Birds, spiders, predators, parasites, and diseases grape quality. Removing basal leaves too early attack leafhopper eggs, nymphs or adults. A will force leafhoppers to deposit their eggs small egg parasite, Anagrus daanei, helps control higher up the vine and might inhibit bud initia- VCLH in some vineyards where parasitism rates tion required for the following year. approach 100% late in the season. A different parasite, A. erythroneurae, parasitizes eggs of the Chemical Control WGLH and is largely responsible for the con- trol of this pest. A. erythroneurae overwinters in Some insecticides registered for the control of eggs of the rose leafhopper on wild and domes- leafhoppers are ineffective for the WGLH and tic roses, apple, blackberry and plum. In early it is important to determine if this species is spring this parasite utilizes eggs of a leafhopper present in your vineyard. If only the VCLH is found on a wide range of mints, including present, natural enemies should be preserved by catnip and catmint. Most vineyards have large applying the lowest effective rate only to areas numbers of A. erythroneura and outbreaks of where the pest has exceeded the threshold level. WGLH are largely associated with sprays of To date, this species has not yet developed insecticides that do not control this leafhopper resistance to insecticides. but are toxic to the parasite. Excessive rates or When monitoring of leafhopper nymphs indi- unnecessary sprays of insecticides will also cates that insecticide sprays are required, apply reduce numbers of other beneficial insects and one of the materials listed in Pest Control Products spiders. Recommended for Use on Grapes in British Columbia, Cultural and Physical Control posted at http://www.al.gov.bc.ca/cropprot/grapeipm/ Leafhoppers prefer excessively vigorous plants grape_pesticides.pdf. and vines should be irrigated and fertilized to It is often sufficient to spray small areas or maintain moderate growth best suited to the treat only the perimeter of the vineyard. production of high quality wine grapes. The use Spraying in this fashion is more economical and of yellow sticky tape applied below the cordon helps preserve beneficial insects. Although in spring can be an economical way to manage reduced rates (640 ml/ha) of carbaryl (Sevin leafhoppers in some vineyards. Although costly, XLR PlusTM) suggested in earlier editions of this this method helps preserve beneficial insects guide to help preserve beneficial insects are and reduces or eliminates the need for addition- likely sufficient to control VCLH, full label rates al insecticides later in the season. The use of will provide only moderate control of the more sticky tape is likely not cost effective for large resistant WGLH. Malathion is currently regis- areas but it can be a useful method where tered for the control of leafhoppers on infestations are confined to small areas or to the grapevines but it is unlikely to be effective edges of vineyards. against the WGLH. AssailTM (acetamiprid) has A recently completed study demonstrated that been shown to be repellent to adults and will removal of basal leaves early in the season (mid cause them to move to unsprayed portions of to late June) when most eggs of the 1st genera- the vineyard. Sprays should be targeted against tion have been laid effectively reduced numbers small nymphs. Although Assail is less damaging of leafhoppers and the incidence of bunch rots. to some beneficial insects compared with many No significant differences were noted in fruit broad-spectrum insecticides, it is toxic to quality other than a slight reduction in yield and predacious thrips and can cause spider mite 5-32 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection numbers to increase. Safer’s Insecticidal SoapTM opment. Damage to grapes occurs during this applied for the control of mites and grape time when the rapidly growing larvae feed on mealybug will reduce leafhopper numbers unopened buds and new shoots. Moths emerge somewhat. Apply soap in high volume sprays in June and remain in a quiescent state through- and ensure that the bottom leaf surfaces are out the summer until fall when they become covered thoroughly. Recent research at AAFC- sexually mature and begin laying eggs that hatch PARC Summerland has shown that some newer into the overwintering larvae. There is a single fungicides and surfactants are repellent to adult generation each year. leafhoppers and their use might eliminate the Damage to grape buds varies with the size of need for additional sprays. Increased movement the cutworm larvae. Small larvae will often of adult leafhoppers within and between vine- burrow into a bud, creating nearly circular holes yards requires greater vigilance, however. that were previously attributed to feeding by adult click beetles. Larger cutworm larvae will Climbing Cutworms chew large, somewhat ragged holes and remove (Lepidoptera: Noctuidae) a large portion or all of the bud. Feeding on To date, 17 species of cutworm have been new, tender shoots can cause the shoots to identified feeding on the buds of grapevines in break or wilt. Larvae climb the vine trunks or the southern interior of British Columbia; the support posts each night and return to the soil three most common species being Abagrotis orbis during the day, or they will find refuge under (Grote), A. reedi Buckett, and A. nefascia (Smith). loose bark of older vines. Damage can vary greatly between years and Monitoring and Spray Thresholds locations and it is not uncommon for only parts of vineyards to be seriously damaged. Cutworm numbers vary over time and between Because populations fluctuate greatly and and often within vineyards. Some vineyards monitoring of cutworm larvae is difficult, rarely experience significant levels of cutworm damage can be considerable. feeding damage while others are damaged yearly. Mild, dry conditions during the winter Identification increase survival rates, while outbreaks of viral Cutworm larvae are smooth, soft, thick-bodied and other diseases that affect cutworms can caterpillars measuring about 4 to 5 cm when reduce numbers to low levels. Cutworm damage fully grown. Larvae typically live in the soil or is often higher in areas with dry gravelly or under debris and sandy soils that do not support good stands of will curl up broadleaf weeds, with drip irrigation systems, or when disturbed as a result of weeds being controlled too early in or handled. the spring before shoots have elongated. Main- Depending on taining a record of previous damage can help the species, suggest which areas need to be monitored most larvae are most closely and where damage is likely to occur first, often light to but bud damage needs to be assessed through- dark brown, and are usually marked with spots out the vineyard. or stripes. Adults are drab moths with bodies New vines planted in untreated land previously around 2 to 2.5 cm long. The hind wings, which in pasture are prone to damage, and larvae are are sometimes distinctly marked, are usually often sheltered and somewhat confined within lighter in colour than the forewings. Adults are the protective milk cartons or sleeves placed active at night and rest during the day in shel- around new vines. Loss of buds on new vines tered locations under bark, debris, or leaves. can retard growth and delay fruiting and they Life Cycle and Damage should be closely inspected in spring for signs of damage and treated when necessary. Cutworms that feed on grapes spend the winter Significant amounts of damage can occur over as small larvae in the soil or under fallen leaves a period of two or three days when the nights or debris. When the weather warms in spring remain warm, and it is especially important to they resume feeding and complete their devel- 2010 Best Practices Guide for Grapes for British Columbia Growers 5-33 5 Crop Protection monitor for damaged buds frequently during greater number of retained buds in spring will this time. At other times it is usually sufficient suffer marginally less damage, but there will be to monitor vines weekly or twice weekly until added costs related to removal of extra shoots. shoots have elongated. An accurate threshold Some grape varieties will produce fruit on based on the degree of bud damage is difficult secondary shoots, but yields will still be reduced to determine, as it is influenced by the variety, and ripening can be delayed or uneven. training system and method of pruning, pres- ence of predators and parasites, and tolerance Chemical Control level of the individual vineyard manager. Sprays of the pyrethroid insecticide PounceTM Suggested economic thresholds from growers (permethrin) should be directed to the soil at range from virtually zero to over 15%; a value the base of vines, to vine trunks, and to support around 3% bud loss is likely for most vinifera posts so that larvae contact the insecticide while varieties. Establishment of spray thresholds moving from the soil to the canopy. Do not should also consider the potential for second- cultivate or disturb the soil for several days after ary pest outbreaks that will require additional treatment. For young vines, sprays should be insecticide sprays later in the season. directed into the milk cartons or other protec- tive structures applied around newly planted Biological Control vines. Avoid spraying insecticides unneces- sarily, as these are very damaging to Cutworm eggs are consumed by various preda- beneficial insects and can result in out- tors and are parasitized by small wasps. Larvae breaks of secondary pests later in the are eaten by ground beetles, hunting spiders and season. birds, and are parasitized by wasps and flies. Fungal and bacterial diseases that attack cut- AltacorTM (rynaxypyr) was recently registered worm larvae are very common, particularly for cutworms on grapes. Rapid cessation of when conditions are cool and wet. The com- feeding and toxicity result largely through bined effect of these natural controls is to ingestion and sprays should be directed to the eliminate most cutworm eggs and larvae. Of the developing buds. Altacor is considered a re- 300 or more eggs laid by a female moth, only a duced–risk material due to its greater selectivity few survive to become reproductive adults. and reduced toxicity to non-target organisms. Even so, damage resulting from the few remain- Follow the label instructions and wear appropri- ing larvae can be considerable. ate protective clothing as for all pesticides. The list of materials registered for cutworm control Cultural Control is likely to change before the next printing of Broadleaf weeds should not be controlled in this guide and it is important to refer to the spring until shoots have elongated and the most recent edition of Pest Control Products first leaves have expanded. Damage is gener- Recommended for Use on Grapes in British Columbia ally much lower in vineyards with mixed ground for appropriate and registered materials. cover vegetation and where broadleaf weeds, particularly winter annual mustards such as Grape Phylloxera Draba verna and Shepherd’s purse, Capsella bursa- (Daktulosphaira vitifoliae (Fitch) pastoris, are present in the vine rows in spring. Larvae are usually more common in areas with Grape phylloxera (Homoptera: Phylloxeridae), well-drained sandy or sandy-loam soils that native to eastern North America, are a type of support fewer broadleaf weeds. Diseases that aphid found on the roots of grapes or in galls infect larvae are also likely to be more prevalent formed on the leaves of wild grapes or hybrid in soils that retain moisture. Control of vegeta- varieties. European vinifera varieties are particu- tion with herbicides or repeated discing during larly susceptible to this pest, and the accidental the fall prior to the establishment of a new introduction of phylloxera to California, Eu- vineyard will help reduce damage to newly- rope, and elsewhere initially devastated these planted vines. industries. Management of phylloxera with Cutworm damage is partially related to pruning insecticides was not successful and the wine practices and grape varieties. Vines with a grape industry was only rescued with the devel- 5-34 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection opment of resistant rootstocks derived from nymphs develop into winged females (alates) American Vitis species or hybrids between these that leave the soil and fly to other vines where and susceptible V. vinifera. Phylloxera were first they lay eggs in the crevices in the bark that identified in the Penticton area in 1961; infesta- hatch into males and females. After mating tions currently are scattered and at relatively low females produce a single larger overwintering levels in British Columbia vineyards, mostly due egg. In spring the eggs hatch into females that to the use of resistant rootstocks and the failure feed on developing leaves and produce galls on of this pest to thrive on sandy soils. susceptible varieties. Nymphs produced in the galls can infest other leaves or migrate down to As early as 1914 it was recognized that grape the roots. Most grapes grown in British Colum- phylloxera consisted of several distinct biotypes bia are not susceptible to leaf galls and the life or races. Biotypes differ in their ability to form cycle here largely consists of asexual forms galls on the leaves of certain cultivars, in the confined to the roots of grapes. For this reason, degree of feeding damage caused to roots, and infestations spread at a relatively slow rate. their propensity to form sexual or winged forms. One study demonstrated that rootstocks Feeding of phylloxera on the roots of grape- with unsatisfactory levels of resistance to phyl- vines results in severe water and nutrient stress loxera in Europe and South Africa were suitable and eventual death of the vines. Roots become for California, Australia and New Zealand. Loss stunted and galled and die prematurely from the of resistance can also occur over time as new injection of harmful saliva and invasion of biotypes of phylloxera arise. fungal pathogens. Depending on vine vigour and the size of the infestation, vines can slowly Identification become stressed and chlorotic, or they can Adults are very small, usually wingless, and less decline rapidly. than 1mm long and half as wide. Colour varies Monitoring and Spray Thresholds from pale green, yellowish-green or light brown on vigorous roots, to brown or orange-brown Vines that fail to thrive and become chlorotic on declining roots; as adults age they become a and unproductive should be inspected for the darker brown or even purplish-brown. Winged presence of phylloxera. Galls on leaves are an sexual forms are rare in British Columbia and obvious indication of phylloxera on hybrid the northwestern U.S. and they do not appear varieties, but damage confined to roots of able to reproduce sexually on vinifera grapes. vinifera wine grapes can be confused with dam- Leaf galls are formed on French-American age from nematodes or root diseases. Carefully hybrids, Concord juice grapes and some root- expose the roots and search for the typical stocks. The relatively small galls on the swellings and dying roots. A hand lens or undersides of leaves are green and roughly dissecting microscope will help verify the circular. These should not be confused with the presence of phylloxera. white or brown fuzzy galls of variable sizes and Insecticide treatments were previously not shapes formed on the undersides of leaves by effective and there are no spray thresholds for erineum (leaf blister) mite. phylloxera on roots. Hybrid cultivars that Life Cycle and Damage develop leaf galls are better able to tolerate or resist feeding damage to roots, but elimination Phylloxera overwinter on roots as small, dark of the leaf gall forms soon after they are detect- hibernating nymphs that complete development ed might help reduce the extent of the in spring to become females that reproduce infestation. without having mated. Two or three generations are produced each year. When populations are Biological Control large or the vines are declining, some newly Biological control of phylloxera has not been hatched nymphs leave the roots through cracks studied in detail. A number of generalist preda- in the soil and migrate to the roots of nearby tors are known to feed on phylloxera in leaf vines. These small crawlers have been known to galls. In Ontario, larvae of two species of climb vine trunks and be blown on the wind for predaceous flies were commonly associated with some distance. In late summer a portion of the 2010 Best Practices Guide for Grapes for British Columbia Growers 5-35 5 Crop Protection leaf galls. Predaceous soil-dwelling carabid phylloxera resistance. Prior to planting it is beetles undoubtedly feed on phylloxera infesting advisable to read appropriate publications and roots, and because they do not produce honey- consult with vineyard managers or consultants. dew, ants are likely to feed on phylloxera rather Vigorous vines resist phylloxera damage better than protect and ‘milk’ them. Although natural than stressed vines. Provision of additional enemies are unable to effectively control popu- water and nutrients can help delay the rate of lations of phylloxera, diseases and predators will decline. Infested vines should not be heavily help keep populations low and reduce the rate cropped and extra care is required to prevent of spread. additional stresses from insects and diseases. Cultural Control Some varieties are more vigorous and are better When establishing a new vineyard, purchase able to resist damage. Phylloxera infestations plants from reputable suppliers and ensure that are more damaging and spread more rapidly planting material is healthy and free of phylloxe- on heavier soils that are prone to cracking, ra. The Phylloxera and Grape Industry Board of while vines planted in sandy soils can be nearly South Australia requires that grapevine nursery immune to attack. material originating from infested areas be Chemical Control immersed for 5 minutes in a hot water bath heated to 54oC (or 50oC for 30 minutes) and MoventoTM (spirotetramat), a systemic insecti- cautions that plants can be harmed by this cide effective against plant-feeding insects treatment. Previous versions of this guide with sucking mouthparts, was recently regis- recommended that the soil should be washed tered for the control of grape phylloxera and from the roots of dormant, well matured nurse- mealybug. Sprays should be applied in a ry plants before they are immersed for 5 minimum spray volume of 500 L/ha as per minutes in a water bath heated to 43.3oC, after the label instructions. which they are immediately moved to a second bath at 51.7oC for 5 minutes. It is important that Wasps the water bath be agitated during the treatment period to ensure an even temperature distribu- A number of species of yellowjacket wasps tion. After treatment the plant material should (Hymenoptera: Vespidae) are pests of grape; be immediately immersed in cold water until it is the most numerous and troublesome being thoroughly chilled. Vespa pennsylvanica (Saussure). Two uncom- mon species of paper wasp (Polistes sp.) are To ensure that phylloxera are not moved from native to our area. The European paper wasp, infested to clean areas on farm machinery, P. dominulus, was found in British Columbia in disinfest all equipment. Less frequent cultiva- 2003 and has since become very common, tion that penetrates the root zone is thought to particularly around buildings. Yellowjackets, be helpful. hornets and paper wasps are important Resistant rootstocks provide an effective predators of grape pests throughout most of means of combating phylloxera. Almost all the year, but in fall they often feed in large resistant rootstocks were developed from numbers on damaged fruit. Wasps are also an crosses between several species of wild grapes annoyance to vineyard workers and to pickers native to eastern and southern North America during harvest operations. Paper wasps are (V. riparia, V. rupestris, V. berlandieri and others). less aggressive than yellowjackets or hornets Some of the more common grape rootstocks and are not as prone to sting. with good phylloxera resistance include SO4, Identification 5BB, 5C, 420A, and 161-49C. Rootstocks vary in characteristics such as vigour and it is often Yellowjacket workers are about 1.5 cm in difficult to select an appropriate rootstock for a length; the abdomen appears largely yellow particular vineyard. Soil types, resistance to with thin black bands. Hornets are slightly nematodes, vine spacing and several other larger and appear largely black with yellow or factors need to be considered in addition to white bands. Paper wasps have thinner bodies

5-36 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection with a more pronounced constriction (stalk) adults and larvae are subject to certain diseases. between the thorax and abdomen. The body The onset of winter eliminates established is dark with some yellow markings, but they colonies and overwintering queens often suc- appear reddish-brown due to the colour of cumb to cold or are eaten by other insects, or the wings and distal parts of the legs. In flight even by mice. the legs of paper wasps dangle visibly below the body. All of these wasps produce paper Cultural Control nests, but the brood cells of paper wasps are Elimination of nests early in the season can be exposed. an effective management strategy, but they are often located outside the vineyard or well Life Cycle and Damage hidden. Aerial nests in trees or under eaves can Yellowjackets and paper wasps overwinter as be removed and placed in a plastic bag at night fertilized females in sheltered locations. These when wasps are inactive. Nests in walls or queens seek suitable nest sites in spring and natural cavities can be treated by blowing or establish a new colony. Nests are initially small, puffing commercial wasp control products into consisting of only a few paper cells, but as the entrance holes at night. Sealing of entrances workers develop they assist in building up can help prevent future nests. colony numbers and the size of the nest. De- Trapping can be used to reduce numbers of pending partly on the species, nests can be in foraging wasps in localized areas. Commercial the ground, under the eaves of houses, in wasp traps are available, or homemade versions hollow trees or the walls of buildings, or ex- can be made from recycled 1 litre plastic pop posed in trees. In fall, in addition to workers, bottles. Sugary solutions are contained in the colonies produce both males (drones) and bottom of the trap and wasps that enter the queens. When freezing weather arrives, all the small holes eventually fall into the liquid solu- drones and workers, as well as the undeveloped tion and drown. Trapping early in the season larvae and pupae are killed. when populations are low is generally more Wasps prey on other insects, scavenge food and effective than attempting to remove large feed on nectar and the juices of fruit. It has numbers of wasps later in the season. For been reported that wasps do not damage fruit additional information on social wasps, man- themselves but take advantage of injury caused agement strategies, and design of wasp traps, by other insects or birds, diseases such as sour visit the University of California Statewide rot, or splitting of fruit. There are contrary Integrated Pest Management Program, 2008, reports, however, particularly relating to the website at: European paper wasp, that they are able to http://www.ipm.ucdavis.edu/PMG/Pestnotes/ directly feed on intact fruit. As mentioned pn7450.html. above, the greatest detriment is from annoyance or injury to pickers. Their stings result in swell- Chemical Control ing and a painful itch and can trigger severe There are currently no insecticides registered allergic reactions in some individuals. specifically for the control of wasps feeding on grapes. Monitoring and Spray Thresholds

Wasps are generally considered to be beneficial Spotted Wing Drosophila or of little economic importance. There are no (Drosophila suzukii (Matsumura)) established thresholds and the need to spray is determined by the tolerance level of individual This potentially damaging pest of grapes was vineyard managers. The recent arrival of the first found in Canada infesting blueberries in the European paper wasp will likely make it neces- Fraser Valley in September 2009, and soon after sary to control wasps more frequently. in fruit fly traps in a cherry orchard near Kel- owna. It is native to Southeast Asia where it Biological Control feeds on a range of soft skinned fruit. Unlike Wasp colonies can be attacked by other wasps. most species of fruit fly (vinegar fly) that feed Eastern and western kingbirds feed on foraging on very ripe, damaged, or rotting fruit, the 2010 Best Practices Guide for Grapes for British Columbia Growers 5-37 5 Crop Protection spotted wing drosophila is able to attack sound, can be made from recycled plastic pop bottles ripening fruit. Surveys are being conducted in containing mixtures of yeast, sugar and water or 2010 in the Fraser Valley and the interior of apple cider vinegar as bait. Fruit can also be British Columbia to help determine the distribu- carefully inspected for the presence of larvae or tion and abundance of this new pest. Although pupae. Adults need to be reared from infested it has been reported to infest grapes in other fruit in order to provide an accurate identifica- regions of the world, it is unknown at this time tion. if it will become an economically important pest If you think you have this pest, consult the of grapes in this province. ‘Spotted Wing Drosophila (Fruit Fly) Pest Alert’ Identification factsheet, BCMAL (www.al.gov.bc.ca/cropprot/swd.htm) for Adult spotted wing fruit flies are slightly larger additional information. (2-3 mm) than other fruit flies and males have a dark grey to black spot toward the outer margin Biological Control of each wing. Females lack the wing spots and Little is presently known about natural control have a saw-like ovipositor visible with the aid of agents of the spotted wing drosophila in west- a good hand lens or microscope. The elongate ern North America. Predators and parasites of creamy white legless larvae, up to 3 mm long, other species of fruit fly are likely to also attack are difficult to distinguish from other species of this species. fruit fly. Cultural Control Life Cycle and Damage Sanitary measures suggested for other fruit It is currently unknown if adults of the spotted crops (i.e. removal of infested and unharvested wing drosophila will successfully overwinter in fruit) are generally not considered to be practical significant numbers in the interior of British for commercially produced grapes. Columbia. Beginning in spring, several gener- ations develop throughout the year on a range Chemical Control of available fruit (strawberry, blackberry, cherry, Ripcord (cypermethrin), Malathion, Delegate etc), including grapes in the late summer and (spinetoram), and Entrust (spinosad) received fall. Typical for fruit flies, females lay large emergency registration for the control of spot- numbers of eggs that hatch rapidly into larvae ted-wing drosophila on grapes for 2010. Entrust that mature at a rapid rate. A generation can is a product approved by the Organic Materials develop in as little as 1 to 2 weeks when temp- Review Institute (OMRI) for use in organic eratures are warm, resulting in rapid increases in vineyards. Sprays are required near to harvest to numbers and significant damage to crops. control this pest, and it is important to consult Larvae of several species of fruit fly develop in the label and observe the pre-harvest interval damaged or decaying grapes late in the season, (PHI). These emergency registrations expire causing little damage to the crop. Female spot- October 31, 2010. Check for current recom- ted wing drosophila, however, can deposit eggs mendations after this date. into undamaged, ripening fruit using their strong serate ovipositors. Feeding by larvae directly damages the fruit, and the holes created during egg-laying allow the entry of disease- causing microorganisms. The presence of fruit fly larvae and pupae in fresh table grapes is also a great concern. Monitoring and Spray Thresholds There are no established thresholds for this pest and it is presently unclear if it poses a serious threat to grapes produced in British Columbia. Fruit fly traps are available commercially or they 5-38 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection

clear wings or wings that appear light grey with Minor or Secondary Pests white bands, or they are pale with dark bands A number of insect and mite pests of grapes on the wings. They are slightly larger to nearly twice as large as the pest species. Nymphs of occur only infrequently or cause significant predaceous thrips have bodies that are banded amounts of damage only after chemical treat- yellow and orange, are reddish purple in colour, ments have reduced numbers of predators and or are pale with the joints of the appendages parasites that normally regulate their numbers. dark. Compared with phytophagous species, The best way to manage these pests, then, is to predaceous thrips have front legs that are properly manage populations of primary pests enlarged and slightly curved that they use for so as to preserve and enhance numbers of grasping prey. These features and the slightly beneficial insects and mites. larger mouthparts are best observed under a dissecting microscope. Thrips Life Cycle and Damage (Western Flower Thrips, Frankliniella occidentalis Adult female thrips overwinter under leaves and Pergande) (Grape Thrips, Drepanothrips reuteri Uzel) plant debris on the ground. In spring they (Flower Thrips, Frankliniella tritici Fitch) deposit their eggs into developing leaf, stem, and flower tissues. The time from egg to adult is Several species of thrips can be found feeding, about three weeks during warm weather, and at least occasionally, on grapes; the three most several generations are produced yearly. Most common are the western flower thrips feed on a wide range of host plants, and thrips (WFT), the grape thrips (GT), large numbers will often move to a succession and the flower thrips (FT). Thrips of new succulent hosts throughout the year. are generally minor pests of wine Both adults and nymphs feed by rasping the leaf grapes, but are important pests of surface and sucking up the escaping fluids. table grapes due to scarring of fruit. Their populations often WFT adults enter vineyards in early spring, increase following applications of often in large numbers, when saskatoon bushes broad-spectrum insecticides that have finished flowering and other native vegeta- reduce numbers of beneficial in- tion is beginning to dry down. In addition to sects. All species feed in a similar ground cover plants, WFT feed on flower and manner, but differences in biology fruit tissues of grapes from bloom to just after and timing of infestations results in fruit set. Their feeding under caps and persistent differential damage to grapes. flower parts causes berry scarring and russeting. White and green grape varieties are also dam- Identification aged when females insert their eggs into fruit, All species have long, slender bodies with dark causing dark spots or halo spots. Feeding on protruding eyes and relatively short beaded developing shoots is occasionally so heavy that antennae. Adults have two pairs of wings that shoots are stunted and leaves deformed, but are heavily fringed along the edges. WFT are damage of this sort often only occurs around dark yellow to brown and 1- 1.5 mm long. GT the perimeter of vineyards. WFT usually decline and FT are both around 1 mm long, the former greatly in numbers following fruit set. FT have a is amber yellow with a yellowy-orange thorax, similar biology and contribute to the damage and the latter is uniformly pale yellow to nearly caused to fruit in spring, but they are not as white. Nymphs of all species are similar in numerous as WFT. appearance to the adults except that they are smaller, slightly paler in colour, and lack wings. GT are generally only found in significant Thrips tend to be very active; adults not only fly numbers on grape during the summer months, but also run and hop rapidly. and their feeding is largely confined to leaves and shoots. Numbers can build up rapidly, Plant feeding thrips should not be confused however, particularly following insecticide with predaceous thrips. Adults of beneficial treatments for other grape pests. Leaf veins can thrips may be dark black or purplish black with be scarred and fail to expand properly, leaf 2010 Best Practices Guide for Grapes for British Columbia Growers 5-39 5 Crop Protection edges can become necrotic, and shoot growth SuccessTM (spinosad) was recently registered for inhibited, resulting in shortened internodes. suppression of thrips on grapes. Insecticidal soap applied for mites and grape mealybug will Monitoring and Spray Thresholds also help suppress thrips populations. WFT often invade vineyards in large numbers for only brief periods in spring and it and the Spider Mites FT are not normally an economic concern for (European Red Mite, Panonychus ulmi (Koch)) wine grapes. Scarring of fruit has not been (Two-spotted Spider Mite, Tetranychus urticaeKoch) shown to affect wine quality and damage to leaves and shoots is usually minor. Damage The main species of spider mites infesting usually occurs over a short period of time, grapes in British Columbia are the European red which makes early detection and control diffi- mite (ERM) and the two-spotted spider mite cult. Inspect table grapes for the presence of (TSSM). They differ somewhat in biology, but WFT and FT in spring from around 75% bloom feeding damage and management strategies are to the end of fruit set and apply insecticides as largely the same. Spider mites should be required. Verify the presence of thrips by considered secondary or induced pests of sharply striking fruit clusters or leaves against a grapes; their numbers increase following the dull white or green coloured surface. The use of broad-spectrum insecticides that decision to spray should be based partly on the reduce numbers of spider mite predators. table grape variety, records of past damage, and Although it is somewhat selective in action and the intended market for the fruit. There are no preserves populations of some predators, the firm thresholds for thrips infesting grapes in insecticide Assail is toxic to predacious thrips British Columbia that are effective predators of mites in B.C. vineyards. Studies in Washington State have also Watch for GT damage to young leaves and shown that the active ingredient in Assail and shoots during summer and early fall. Use an related materials increases spider mite reproduc- eyepiece or magnifying glass to verify that thrips tion. Due to its persistence, increases in mite are present. As for fruit clusters, leaves and numbers can occur up to several months after shoots can be held over a piece of white card- application. board and sharply hit to dislodge the thrips. Control on mature vines is usually only warrant- ed when growth is stunted sufficiently early in the summer to delay ripening and affect growth the following season. Biological Control Predatory bugs such as the minute pirate bug (Orius tristicolor), anthocorids (Anthocorus melanoce- rus), and Deraeocoris (Deraeocoris brevis) are all known to feed on thrips. Studies in the Okana- gan and Similkameen Valleys have indicated that predatory thrips are important regulators of pest thrips populations. In the laboratory, predatory Identification thrips at a density of one every 10 to 15 leaves is Adults of both species are small, around 0.5 mm sufficient to control WFT. in length, and just barely visible to the naked Cultural Control eye. They are nearly spherical in shape and have eight legs and short piercing mouthparts. The So that thrips are not forced to feed on table ERM is dark red in colour with long pale hairs grapes when they are most susceptible to fruit (setae) projecting from small pale circular areas damage, avoid mowing cover crops during on the dorsal surface. The oval eggs are bright bloom and fruit set. orange with a distinctive hairlike projection on Chemical Control the upper side. The TSSM varies in colour from pale yellow to greenish yellow to bright orange; 5-40 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection the common pale form has a distinct dark dorsal mite count. A good hand lens or low-power spot on each side of the body. Its eggs are dissecting microscope would help provide white. Both species feed on the undersides of accurate counts of infestation levels. A fairly leaves. TSSM usually congregate in clusters and reliable method is to monitor damage to leaves produces large quantities of silk webbing, while and spray when a moderate amount of ‘bronz- ERM produce less webbing and are more evenly ing’ has occurred, around 10% defoliation. distributed over the leaf surface. Because mite numbers can increase very rapidly it is necessary to monitor grapes frequently Life Cycle and Damage during hot weather. ERM, our most common species, pass the When monitoring for mite damage it is useful to winter as eggs laid on vine canes and trunks. consider previous infestation levels. Vineyards Eggs hatch in spring and the young microscopic with low chemical inputs that have not experi- nymphs begin to feed on young foliage. TSSM enced severe spider mite outbreaks in the past overwinter as fertilized females under the bark are unlikely to require treatment, while those or in other sheltered areas around the base of that have been treated with broad-spectrum vines. When warmer weather arrives in spring insecticides should be observed closely. the females begin to feed and deposit eggs. Both species can produce around six to eight over- Biological Control lapping generations each season, and all stages Spider mites were of minor importance prior to can be found on grapes at any time during the the widespread use of synthetic pesticides. Due summer months. Females of both species are largely to the harmful effects of pesticides on capable of producing 200 or more eggs each populations of predators, spider mites are now and development can be rapid during warm the most important pests of grapes in many weather. Spider mite populations can, there- regions of the world. The first course of fore, explode rapidly under favourable action for the management of spider mites conditions. is the preservation and enhancement of Both adults and nymphs feed by piercing beneficial species. Pesticides should only be individual leaf cells and removing the fluid applied when necessary and only to parts of the contents. Healthy grapevines can tolerate vineyard where pest populations are sufficiently moderate numbers of spider mites, which will high to warrant control. Whenever possible cause chlorotic spots on the leaves. Heavy select materials that are least damaging to non- feeding results in brown leaves that fall prema- target species. Numbers of spiders and benefi- turely; reducing photosynthetic activity and vine cial insects are usually higher in vineyards with vigour. Heavy feeding damage can delay ripen- permanent, mixed groundcover that provides ing of fruit. The large amount of webbing pollen and alternate sources of prey. Proximity produced particularly by the TSSM is also a to uncultivated or unsprayed areas allows cosmetic problem for table grapes. beneficial insects to re-colonize vineyards following spray treatments. Monitoring and Spray Thresholds Several species of predatory mites (e.g. Metasei- Spider mites rarely cause significant damage to ulus, Typhlodromus and Amblyseius species) feed on grapes prior to mid-summer. No firm thresh- spider mites and their eggs. Most beneficial olds have been developed for spider mites on mites are a pale opaque colour but they can grapes in British Columbia, but approximate appear light orange if they have been feeding on guidelines can be suggested from research ERM. They are oblong in shape and slightly conducted in other countries. In Europe, a smaller than adult spider mites. The long-legged threshold for ERM on grapes was determined orange whirligig mite (Anystis agilis) is uncom- to be 60 to 70% infested leaves in spring, while mon on grapes in British Columbia Like most in summer leaves with 1 or more mites should other predatory mites, this large species is more not exceed 30 to 45% of total leaves on a shoot. active than its prey. Predatory mites are very Because a similar threshold has been suggested for TSSM in Switzerland, numbers of both species can be combined into a single spider 2010 Best Practices Guide for Grapes for British Columbia Growers 5-41 5 Crop Protection sensitive to a range of pesticides, including Pest Control Products Recommended for Use on sulphur fungicides and pyrethroids such as Grapes in British Columbia and rotate materials permethrin (PounceTM). with different modes of action (chemical group) to help prevent development of mite A number of spiders and predatory insects feed resistance. on spider mites or their eggs. Many species, such as the minute pirate bug (Orius tristicolor), are generalist predators that do not specialize on Grape Erineum Mite mites, while others such as the aptly named (= Grape Leaf Blister Mite, Colomerus vitis spider mite destroyer, Stethorus picipes, are very (Pagenstecher)) effective predators that feed almost exclusively Identification on mites. Stethorus picipes is a small, dark species of ladybeetle with a slightly hairy appearance. Adult erineum mites are only 0.2 mm long and a The elongate bodies of the larvae are also nearly dissecting microscope is required to observe black in colour with a body covered with nu- them properly. Their creamy pale bodies are merous hairs. At least four species of predatory elongate with only two pairs of legs. Although thrips can be found in Okanagan Valley vine- erineum galls can be confused with certain yards; adults of three of these are black, while fungal diseases or phylloxera leaf galls by inex- the fourth, the six-spotted thrips, Scolothrips perienced growers, their characteristic sexmaculatus, is pale with dark spots on the appearance is the best way to identify these wings. All 4 species feed on spider mites, and pests. The hemispherical concave galls or healthy numbers of these predators are usually erinea formed on the undersides of leaves associated with low populations of their prey. initially have a felty white appearance due to The western flower thrips is considered a pest the presence of densely packed long leaf of grapes, but it is also known to feed on the hairs. Opposite to these galls, bumps will be eggs of spider mites. visible on the upper surfaces of leaves. These swellings are a reddish colour in spring and turn Cultural Control green as the leaves mature. Small numbers of Vineyards can be managed in ways that help mites feed on the dense hairs in each gall, which alleviate mite problems. Hot, dry and dusty eventually turn brown. Having been reported conditions favour the buildup of spider mite recently from Washington State, two other populations. Where mites are a problem, road- forms of erineum mite, the leaf-curling strain ways can be treated with oils or other materials and bud-inhibiting strain are possible in British to reduce dust. Vineyards that are continuously Columbia The former causes slight to severe cultivated will produce more dust than those downward curling of leaves in summer with with permanent ground covers. Moreover, a stunting of shoots and increased growth of permanent mixed groundcover will support lateral shoots. Feeding of the bud-inhibiting greater numbers of beneficial insects and strain on buds causes a range of abnormalities, predaceous mites. Compared with bare soil, including scarified shoots, short zigzagging planted aisles will decrease air temperatures and internodes, dead terminal buds and malformed raise humidity levels somewhat, providing less leaves. For additional information on erineum favourable conditions for spider mites. Spider mites and other pests of grapes, visit the Uni- mite populations can become elevated on vines versity of California Integrated Viticulture suffering severe drought stress, and these plants Online website (Viticultural Information> are also less able to tolerate damage. Overhead Insects and Mites). irrigation will help reduce mite infestations. Life Cycle and Damage Chemical Control Adult erineum mites overwinter under the scales A number of miticides (e.g. AcramiteTM, of buds. Mites move in spring to developing KelthaneTM , EnvidorTM and PyramiteTM) are shoots and create galls on young leaves around registered on grapes for mite control. Insecti- the fruiting zone. Several generations are pro- cidal soap applied for the control of duced each year, with new galls developing leafhoppers will help suppress mites. Refer to higher up the shoots. Beginning in late summer, 5-42 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection adult mites move back to the buds for winter. mites and sprays of organophosphates (e.g. malathion and SevinTM) for control of leafhop- Leaves with a few too many erineum galls pers will also reduce numbers of erineum mite appear to function normally and there is little or somewhat. no economic damage to mature vines until almost all leaves are covered with galls. Even then, damage usually only occurs if vines are Grape Leaf Rust Mite also suffering from other stresses. Establish- (Calepitrimerus vitis (Nalepa)) ment of newly planted vines can be delayed Grape leaf rust mite, which belongs to the same somewhat by erineum mite feeding, which will family (Eriophyidae) as grape erineum mite, was retard or reduce fruiting. identified for the first time on grapes in the Monitoring and Spray Thresholds Okanagan Valley in 2009. Growers are referred to the following source for additional infor- Erineum galls are usually very apparent during mation: Grapevine pests and their management, routine vineyard operations. Grape varieties by A. Loch. Primefact 511, New South Wales differ in susceptibility to this pest and it is Dept. of Primary Industries, NSW Australia important to check individual blocks for the posted at: www.dpi.nsw.gov.au/primefacts. presence of mites. In order to prevent prema- ture loss of leaves, new vines should be Identification inspected and treatments applied if large num- A microscope is required to properly identify bers of galls are found on most leaves during these 0.2 mm long pale white wormlike mites the spring or summer months. that closely resemble erineum or blister mites, Biological Control but do not form leaf galls. They are much smaller than spider mites and elongate rather The western predatory mite, Galendromus than round, tapering at the rear, and having two occidentalis, is an important erineum mite preda- pair of legs near the head. Their presence is best tor. Predaceous thrips will feed on exposed determined by the bronzing of leaves during mites, but their effectiveness is likely limited July and August that results from their feeding. when mites are protected within the dense Unlike spider mites that cause similar damage to hairs of the galls. leaves, grape leaf rust mites do not produce Cultural Control webbing. New plants may become infested in the nursery. Life cycle and damage Ensure that material used to establish new Adult rust mites that spend the winter under vineyards is free of mites and other pests or bark or bud scales move in spring to the devel- diseases. Removing galled leaves can control oping buds to feed and lay eggs. Large numbers light infestations to some extent. Research of adults concentrated on the available green conducted in the Okanagan Valley demonstrat- tissue in early spring can damage buds, resulting ed that removal of infested leaves in May from in deformed leaves, scarring of shoots, reduced Sauvignon Blanc vines did not alter yields or shoot growth, and even bud death. Early season fruit quality. rust mite damage can be confused with cold Chemical Control injury or damage from other causes. Damage becomes less visible as the season progresses Erineum mite is seldom a problem in vineyards and shoots lengthen. Immature mites that hatch where sulphur is applied routinely for powdery over a period of several weeks feed under the mildew control. Applications of sulphur (e.g. bud scales, eventually moving to feed on devel- KumulusTM DF, or wettable sulphur) are oping leaves. Unlike spider mites, rust mites most effective early in the season when galls infest equally the upper and lower leaf surfaces. are first being formed on new leaves. Sulphur Many generations are produced throughout the sprays should not be used on Foch or Vitis summer, and before leaves drop in the fall adult labrusca varieties, as they are susceptible to leaf rust mites migrate to the cordon and trunk for and fruit damage. Miticides (acaricides) such as the winter. Bronzing of leaves is most obvious PyramiteTM or KelthaneTM applied against spider 2010 Best Practices Guide for Grapes for British Columbia Growers 5-43 5 Crop Protection during July and August, but damage to leaves is Identification not thought to cause serious damage to the vines. Extensive bronzing of leaves is an indica- The grape mealybug (Homoptera: Pseudococ- tion that rust mites need to be controlled the cidae) has a flattened, oval pink body covered in following spring. a mealy white wax coating. It is somewhat segmented in appearance, but the divisions Monitoring and Spray Thresholds between head, thorax and abdomen are not distinct. Mature wingless females are about 5 There are no established thresholds for this mm long. They have long waxy filaments along pest. Control is indicated when a significant the edge of the body that are longest at the rear proportion of leaves become bronzed in late and become progressively shorter toward the summer. front end. Large numbers of eggs are laid in Biological Control cottony masses. The smaller, winged males have a pair of long, white anal filaments. Yellow to As for erineum mite, western predatory mite, brown crawlers that emerge from the oval, Galendromus occidentalis, other mite predators, and orange eggs are not covered in wax. All stages predacious thrips are often able to keep rust are mobile. mites in check. To maintain healthy popula- tions of beneficial insects and predatory mites, it Life Cycle and Damage is important whenever possible to limit the use Females move in late fall to old wood and lay of insecticides and to apply selective materials overwintering eggs in cottony egg masses under that are less toxic to predatory mites. loose bark. Crawlers, some of which might have Chemical Control hatched in fall and remained dormant through- out the winter, move to new shoots in spring. A successful rust mite control program devel- Grape mealybugs mature around mid-summer oped in Australia relies largely on spring and produce a 2nd generation that matures in applications of sulphur (e.g. KumulusTM DF, late autumn. They can occur on all plant parts or wettable sulphur) in high volume sprays but are more common in summer on leaves and during bud swell to woolly bud stage. new growth, usually hidden within the canopy. Sulphur sprays should not be used on Foch or Vitis labrusca varieties, as they are susceptible to Damage is similar to that for soft scale. Plant leaf and fruit damage. There are no miticides sap is removed during feeding and large currently registered for the control of grape leaf amounts of honeydew foul the fruit and pro- rust mite. mote the growth of sooty mold fungus. Most fruit damage occurs during the development of Grape Mealybug the second brood in late summer. Mealybugs (Pseudococcus maritimus (Ehrhorn)) can infest grape bunches and are known to transmit certain strains of leafroll virus. Mealybug were seldom a concern on grapes prior to the widespread use of synthetic insecti- Monitoring and Spray Thresholds cides. Individual bunches of table grapes that To detect when crawlers are active, remove the touched infested vines would occasionally loose bark in an area near the infestation and become infested. Largely due to the detri- encircle the vine with clear tape applied sticky mental effects of broad-spectrum side out, or use double sided adhesive. Replace insecticides on beneficial insects, damaging the tape every three or four days and check for populations of mealybug have become more the yellowish brown crawlers. A good magnify- common in recent years. As for many other ing glass or dissecting microscope is useful for secondary pests, the most important manage- this purpose. Unlike scale insects, grape ment strategy is to apply chemicals against mealybug prefer vigorous vines with thick major pests (leafhoppers, cutworm) only when canopies. The need to inspect vineyards for required and only to portions of the vineyard mealybugs can be based partly on past infesta- where control is warranted. Whenever possible, tions, vigorous growth, and prior use of broad- select pesticides that are least damaging to spectrum insecticides. predators and parasites. 5-44 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection

Biological Control http://www.al.gov.bc.ca/cropprot/grapeipm/ grape_pesticides.pdf. Parasitism of grape mealybug has not been studied in British Columbia Research in Cali- fornia has shown that at least six species of Scale Insects parasitic wasps attack grape mealybug - late (European Fruit Lecanium Scale, Parthenolecanium summer and fall rates of parasitism often exceed corni (Bouché)) 90%. Predaceous midge larvae attack mealybug (Cottony Maple Scale, Pulvinaria vitis L.) egg masses. Lacewings, several species of lady About a dozen species of scale insects are beetles, and many other generalist predators known to attack grapes in various regions of the feed on adults. Mealybug and other homopteran world, but only two are commonly found on insects (scale, whitefly, aphids, etc.) are suscep- grapes in British Columbia The European fruit tible to several diseases, including Entomopthora lecanium scale (EFLS) and cottony maple scale fungus. (CMS) are both soft scales (Homoptera: Coc- Cultural Control cidae) that rarely cause economic injury to grapes. They are a greater concern in the pro- Mealybugs prefer vigorous vines. Ensure ade- duction of table grapes. The large quantities of quate nutrition and moisture to produce an honeydew they produce supports the growth of optimum crop, but avoid excessive vigour. sooty mold fungus that can leave fruit unmar- Research in California has shown that fruit on ketable. Two species of hard scale (Homoptera: cane-pruned varieties is less likely to suffer Diaspididae), the oystershell scale, Lepidosaphes damage compared with spur-pruned vines. ulmi L., and San Jose scale, Quadraspidiotus Clusters on cane-pruned vines hang farther perniciosus Comstock, can occasionally be found away from the mealybug overwintering sites on attacking 2 year old wood of weakened vines. old wood. Earlier varieties often escape damage Hard scales do not produce large amounts of as they are not exposed to honeydew to the honeydew and are currently of little importance same extent as later varieties. to the B.C. grape industry. Heavy infestations of mealybugs and other Identification honeydew-producing pests of grape are usually tended by ants that feed on the sugary excretion Female EFLS, also known as brown apricot and protect the mealybugs from predation. scale, when fully grown have a chestnut brown, Control of ants can often contribute to a signifi- smooth and slightly shiny protective shell that is cant decline in mealybug numbers. For small around 5 to 8 mm long and slightly longer than backyard plantings with an isolated infestation, wide. Certain races in some regions reportedly painting a sticky material around vine trunks produce male scales, but most females repro- and posts and ensuring that ants cannot gain duce without mating. The small nymphs or access to the mealybugs often eliminates the crawlers that hatch from the small oval, pearly problem. Trials in California have also shown white eggs are yellow to orange in colour. that sprays directed against the Argentine ant, Mature female CMS are similar in size, shape Iridomyrmex humilis, controlled damaging popula- and colour to EFLS, except that a mass of tions of the obscure mealybug, Pseudococcus cottony material containing the eggs, up to affinis. Insecticides are not currently registered 1,000 per sac, extrudes from the rear end. The for the control of ants in BC vineyards. much smaller winged males produced in late summer have no mouthparts and live for only 1 Chemical Control or 2 days. Males mate with the immature fe- Malathion, Diazinon and Safer’s Insecticidal males. Mature scales of both species become Soap can be applied against the crawler stage, brittle after the eggs are laid in mid-summer and while MoventoTM (spirotetramat) is active can easily be detached from the one to three against all stages due to its good systemic year old wood with a fingernail. The smaller activity. Consult the BCMAL fact sheet, Pest hard scales (1-2 mm), which are much longer Control Products Recommended for Use on Grapes in than wide, remain firmly attached to the canes British Columbia, posted at even after death.

2010 Best Practices Guide for Grapes for British Columbia Growers 5-45 5 Crop Protection

Life Cycle and Damage Biological Control EFLS and CMS overwinter as partly grown Biological control of scale on grapes in British scales on new canes. Growth resumes in spring Columbia has not been investigated in any and females reach maximum size around early detail, but on other crops and in other regions summer when they begin to lay eggs. The newly of the world they are known to be heavily hatched scale called crawlers hatch and disperse parasitized by several species of wasps and flies. during July and August to the undersides of They are preyed upon by lacewings, lady beetles, leaves where they settle and feed until early fall, and other generalist predators. English sparrows when they migrate to the current year=s wood and several species of warblers that feed on fully and develop a hardened protective shell for the grown soft scale have been known to curtail winter. infestations. Both species of soft scale feed on the phloem of Cultural Control grapes and a large number of other woody plants, including many fruit trees and ornamen- Healthy vines of moderate vigour are less tals. Scales are not usually abundant on grapes susceptible to scale infestations and are better grown in British Columbia, and direct feeding able to withstand damage. Routine pruning damage from the removal of plant fluids is removes many scales and a small infestation can rarely a cause for concern. They appear to be pruned out in spring or early summer. prefer weak vines, however, and the additional Chemical Control stress might be sufficient to hasten death. Of TM greater concern, they produce vast amounts of Movento (spirotetramat) is registered for the honeydew that can turn grape bunches into suppression of lecanium scale. Malathion and sticky, unmarketable messes. Additionally, insecticidal soap will also help control the active honeydew supports the growth of sooty mold crawler stages in summer. Repeat applications fungus which further disfigures the fruit. might be required as long as crawlers are active. Monitoring and Spray Thresholds Snailcase Bagworm Because scale infestations often occur on only a (Apterona helix Siebold) single vine or a few vines in a small area, they Identification can be difficult to detect. Partly-grown scales might be observed during pruning, or watch for This introduced moth honeydew on leaves and fruit during spring and (Family Psychidae) remains early summer. Ants feed on the honeydew and throughout most of its life will protect the scale from predators. They can within a snail-like case often be seen in large numbers hurriedly run- made from particles of soil ning up and down posts or vine trunks to and and sand bound together from infested canes. with silken threads. When fully grown the coiled case To detect when crawlers are active, remove the is approximately 4 mm in loose bark in an area near the infestation and diameter. There are no males and the wingless encircle the vine with clear tape applied sticky female moths remain inside the case to deposit side out or use double sided adhesive. Replace their eggs without having mated (parthenoge- the tape weekly and check for the orange netic reproduction). Large aggregations often coloured crawlers. A good magnifying glass or form on posts, tree trunks, or vine trunks in late dissecting microscope is useful for this purpose summer. There are no established thresholds for scale infestations. Small numbers of scale on a Life Cycle and Damage healthy vine are unlikely to cause damage; Young caterpillars overwinter within the case treatment is usually only required when the formed by the mother. They drop to the ground excretion from large infestations fouls table in spring, form C-shaped cases, and begin to grapes. feed on a wide range of weeds, native plants and

5-46 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection cultivated crops. Damage consists of small European Earwig excavated holes on the leaf surface. As the larva (Forficula auricularia L.) grows it eventually expands its case into the typical snail-like, helical shape. In mid-summer The European earwig is both a beneficial the fully grown larvae will climb vines, posts or insect and a pest of table grapes. All stages buildings, attach themselves firmly with silk, and feed on small, soft-bodied insects such as small pupate within the case. Several weeks later the leafhopper nymphs and will scrape leafhopper females emerge, lay eggs, and then exit the case eggs off of leaves. In fall they feed to some to die. The eggs hatch in late summer and the extent on damaged grapes and their presence in small first instar larvae spend the winter within table grapes is not appreciated by some con- the protective cases. There is only one genera- sumers. On grapes produced for wine, they tion per year. should be considered important generalist predators. Monitoring and Spray Thresholds Identification Larvae of the snailcase bagworm cause minimal feeding damage to leaves and they are not Adult earwigs (Order Dermap- considered economic pests of wine grapes. The tera) are dark brown, about 1.5 large aggregations are easily detected on build- cm long, with a pair of forcep- ings, posts, wires, and the trunks of vines. If like appendages (cerci) at the contamination of table grapes is a concern, rear of their elongate bodies. The inspect vines and apply control measures before anal forceps of females are long the overwintering aggregations form in late and straight, while those of summer. The non-feeding overwintering stage, males are curved. Earwigs seldom fly and the secure within the case, is not susceptible to membranous hind wings usually remain folded insecticides. up under the short leathery forewings, exposing the abdomen. The four nymphal stages resem- Biological Control ble the adults except that they are smaller and Because it has not yet been adequately studied, wingless. Earwigs are largely nocturnal and hide natural enemies of this pest of grapes in British during the day, often in large aggregations, in Columbia are unknown. The protective case cracks and crevices, or under bark. When would provide some protection from certain disturbed they move quickly. generalist predators, but predators, parasites and Life Cycle and Damage diseases undoubtedly take their toll. Adults overwinter in the ground in earthen cells. Cultural Control Clutches of eggs laid in cells in the top 5 cm of Snailcase bagworm prefer moist areas with thick soil in the fall and spring are opened by females vegetation. Avoid excessive irrigation and drain in spring to release the young nymphs. Adults areas that puddle or remain damp. Proper are semi-social and tend their young for a period drainage will also help reduce grapevine root of time after birth; nymphs later disperse to diseases. Occasional discing or mowing of areas secure locations under rocks, in crevices, or of the vineyard where bagworm are a problem under bark. Adults develop by midsummer and can help reduce infestations. there is only a single generation per year. Ear- wigs are nocturnal and feed at night on dam- Chemical Control aged fruit, leaves, small soft bodied insects, and other foodstuffs. They rarely damage grape DipelTM (Bacillus thuringiensis) is registered for snailcase bagworm control on grapes and sprays leaves. applied for the control of other insects will Monitoring and Spray Thresholds provide some protection. For this reason, they are more common in organic vineyards or Rolled up newspaper or cardboard, or flat conventional vineyards with low chemical boards placed on the ground, can be used to inputs. monitor earwigs. It might be possible to use these same refuges to enhance their numbers in wine grapes. 2010 Best Practices Guide for Grapes for British Columbia Growers 5-47 5 Crop Protection

Biological Control bodies usually in shades of brown or black. The segment behind the head has small projections Birds, large spiders, wasps and ground beetles that point backward on each side of the body. prey on earwigs. Earwigs, in turn, feed on the Adults of most species are around 1 to 1.5 cm eggs and small nymphs of leafhoppers and in length, but some are significantly larger. on other soft bodied insects. When adults are placed upside down in the Cultural Control palm of a hand or gently held between finger and thumb they will rapidly flex their bodies at Tillage in spring and fall will destroy some of both ends and attempt to right themselves or the earthen cells. For table grapes, mowing, escape with a characteristic clicking action. tillage, removal of loose bark from vine trunks, and sanitation will remove hiding places and Life Cycle and Damage help reduce earwig numbers. They can be kept out of small plantings of table grapes by apply- Adults that have spent the winter under debris ing sticky tape or commercial Stickum around and leaves emerge with the arrival of warm trunks and posts. Washing table grapes after weather in spring to feed on the tender buds harvest will help dislodge many earwigs. Ear- and leaves of a wide range of plants, including wigs are less likely to seek refuge in table grape occasionally grapes. They are often quite com- varieties with loose, open fruit bunches. mon on flowers where they feed on soft tissues and pollen. After feeding for a short time, Chemical Control females begin to deposit eggs into the soil. In Earwigs are sensitive to most insecticides two or three weeks the eggs hatch into small and sprays applied for the control of other slender ‘worms’, the larvae, that develop in the grape pests will usually also provide control soil throughout the summer. Click beetles can of earwigs. Commercial earwig baits are persist for a long time without feeding and they also available. often require more than one year to complete development to the adult stage. Click Beetle Larvae are not known to damage the roots of (Coleoptera: Elateridae) grapes to any extent, preferring to feed on the roots of weeds or grasses. As for cutworm Click beetles where formerly considered to be larvae, feeding of adults on buds of grape causes important pests of grapes in British Columbia, the buds to die. Yields can be reduced and but extensive study in Okanagan vineyards has ripening of fruit can be uneven and delayed. shown that damage attributed to click beetle Little damage occurs after bud break. adults was in fact caused by half grown cut- worm larvae. Several species will feed occasion- Monitoring and Spray Thresholds ally on buds of grapes, but control is usually not Adult click beetles feed on buds so infrequently warranted. Click beetles are also not considered that monitoring for these pests is generally not pests of grape in Washington State. warranted. The presence of adult click bee- Identification tles in a vineyard does not indicate feeding or correlate with damage. There are no Click beetle larvae, established thresholds in British Columbia called wireworms, have relating click beetle numbers to bud damage. To long, slender, hard determine if bud damage is due to click beetles bodies that are a light or cutworm larvae, it is best to inspect vines tan to a light orangey- with the aid of a flashlight soon after dark on brown in colour, and warm spring nights. appear somewhat shiny and polished. Their Biological Control short legs and cylindri- Little information is available on the biological cal slender bodies allow them to burrow control of click beetles in British Columbia through the soil to feed on the roots of plants. Adult beetles have elongate, somewhat flattened

5-48 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection

Cultural Control Grasshoppers As for climbing cutworm, the presence of Adults and nymphs of several species of grass- broadleaf weeds in spring helps reduce damage hopper (Orthoptera: Acrididae) feed on grape to grapes. leaves usually beginning in late summer when preferred hosts begin to dry up. Feeding by Chemical Control these well-known, long-legged jumping insects Chemical control of click beetles is generally not consists of chewing damage to leaf margins warranted and none are registered specifically most often on lower leaves. Grasshoppers for adults on bearing vines. Sprays for cutworm suffer from pathogenic diseases when popula- larvae should help control adult click beetle. tions are high. Preying mantids, toads, and many species of birds feed on adults, while smaller Miscellaneous Insect Pests nymphs are attacked by spiders and a number of predatory insects such as ground beetles. In addition to the major and minor grape pests described in previous sections, a number of Whitefly insects attack grapes only very rarely and are Several species of whitefly (Homoptera: generally not of economic importance in British Aleyrodidae) occasionally infest grapes. Over- Columbia Following are brief descriptions of a wintering whitefly are relatively rare in B.C. few of these occasional pests. Some sub-tropical and tropical species, such as Black Vine Weevil the common greenhouse whitefly, Trialeurodes (Otiorhynchus sulcatus F.) vaporariorum (Westwood), infest outdoor plants each season from infested greenhouses, house Weevils spend the winter in the soil as pale, plants, and vegetable and ornamental trans- legless larvae feeding on the roots of a wide plants. Adults are small, around 2 mm in length, range of plants. The 1.5 cm long flightless black with two pair of wings that are covered with a adult beetles have a long, broad >snout= typical fine, white powder. They somewhat resemble of weevils (Coleoptera: Curculionidae). The small white moths. The minute crawlers are thick, roughened front wings are fused together. mobile for only a few hours until they settle and Adults feed during summer on grape clusters develop into nearly translucent, scale-like and leaves and sometimes girdle fruit clusters. immobile nymphs. The >scales= have a fringe Weevils are active only at night and remain of waxy material projecting from the bottom hidden under plant debris or loose bark during edge; the distribution and numbers of the the day, making detection difficult. Look for projections can assist in species identification. leaves with deeply notched edges not associated The pupal stage that develops inside the case on with damage from other chewing pests. Traps the undersides of leaves is somewhat bulbous can be made from cardboard loosely wrapped and appears segmented. There are several around vine trunks where the weevils will hide generations per year. Whitefly feed by sucking during the day. They are mainly a problem on juices from the leaves, much as scale insects do, older vines and in coastal production areas. and they also produce large amounts of sugary Wood-Boring Beetles honeydew. Populations are controlled by para- sitic Encarsia wasps that turn the scales black, by Two or three species of wood-boring beetles several predatory insects, and by pathogenic can occasionally infest older canes and vine fungi. trunks. Depending on the species, adults are brown to black, cylindrical in shape, and from Western Grape Rootworm 5-10 mm in length. They have hardened fore- The western grape rootworm, Bromius obscurus wings typical of beetles and indistinct body (L.), is a widespread pest of grapevines in sections. Adults burrow into the spurs and Europe and California, but damage to grapes in canes at the base of new shoots, causing them British Columbia was not previously reported to wilt or break. The pale larvae or grubs bur- until recently when an outbreak occurred in the row through living or dead tissues. Damage Kelowna area. Fully grown larvae are C-shaped usually occurs on older or diseased vines. white grubs about 7 mm long with yellowish 2010 Best Practices Guide for Grapes for British Columbia Growers 5-49 5 Crop Protection brown heads and dark mouthparts. Adult buffalo treehopper, S. bisonia Kopp & Yonke, beetles are about 4 mm long and somewhat which also reportedly feeds on grapevines, has hairy with nearly black heads and bodies. the hump-backed appearance of the American Adults, which are all females, start emerging in Bison after which it is named. Mainly restricted May and feed on the expanding leaves of to the south end of the Okanagan Valley, grapes, causing long slit-like holes. Larvae damage caused by the three-cornered alfalfa initially feed on root hairs before tunneling into treehopper can resemble leafroll virus. In the roots of grapevines. Feeding by western summer late instar nymphs will produce a series grape rootworm larvae is known to cause the of feeding punctures around leaf petioles or death of vines in California due to direct dam- stems, resulting in decreased flow of water and age to the roots and entry of secondary nutrients and eventual reddening of leaves pathogens. Additional information is available at beyond the feeding site. The initial feeding www.al.gov.bc.ca/cropprot/bromius_obscurus. punctures coalesce into a darkened band of pdf. sunken tissue encircling the stem or leaf petiole. Although damage is often restricted to lateral Cicada shoots and generally not of economic concern, Adult minor cicada, Platypedia minor Uhler growth of newly planted vines could be stunted (Homoptea: Cicadidae), are about 20 mm long in areas with lots of alfalfa or other suitable host with 2 pair of large, transparent wings held plants. roof-like over the body. The pale, wingless nymphs have enlarged front legs that they use to Additional Information dig through soil. Cicadas are mostly known Other useful sources of information on pests of from the loud buzzing or clicking noises that grapevines: males produce on hot summer days. They are difficult to locate and will move around to the Grape pest Management, 2nd Edition. opposite side of trees or posts when ap- University of California, Agriculture and Natural proached. Damage to individual shoots occurs Resources, Pub. No. 3343. 2008. occasionally when females deposit eggs into UC Integrated Viticulture Online. University of canes with their long, saw-toothed ovipositor. California website. Main Menu>Viticultural Deposition of several eggs into a cane can Information>Insects and Mites. weaken it or cause it to break. The oviposition damage is recognizable by the slivers of wood UC IPM Online. University of California protruding from a series of punctures. Newly website (www.ipm.ucdavis.edu). Main hatched nymphs drop to the ground to spend menu>agriculture>grape>insects and mites. two to three years feeding on the roots of 2009 Pest Management Guide for Grapes in plants. It is not known if they feed on the roots Washington. WSU Extension Publications. of grapes. Revised Jan 09. Three-Cornered Alfalfa Treehopper (Free downloadable PDF version at: Adult three-cornered alfalfa treehopper, Spissisti- cru.cahe.wsu.edu/CEPublications/eb0762/eb07 lus festinus (Say) (Homoptera: Membracidae), are 62.pdf). green in colour and about 6 mm in length. The Grapes: Factsheets and Publications. pronotum is elongated to the sides and extends BC Ministry of Agriculture and Lands website to the rear of the abdomen so that they look (www.al.gov.bc.ca/grape/factsheets.htm). somewhat triangular when viewed from the front. Lacking the large side projections, the

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5.4 Weeds organic mulches. Selection and management of appropriate ground cover vegetation will assist in managing weeds. For Chemical Weed Control information on managing vineyard cover crops see section 4.5 Vineyard Floor Management. Be cautious and accurate when using herbicides. Use proper equipment maintained in good condition The elimination of all vegetation around young and calibrated accurately. Consult the section on grape vines is essential to eliminate competition and Pesticide Application in this publication and the promote satisfactory growth that will result in early section on Pesticide safety. commercial yields. Newly planted grape vines are poor competitors for moisture and nutrients. Safe and effective chemical weed control Heavy sod will cause severe stunting of young measures are widely used. Successful chemical vines. Effective chemical and mechanical weed weed control always depends on the proper control measures are available. application of the correct amount of recommend- ed herbicides. Pre emergence residual herbicides Non-Chemical Weed Control (diuron, dichlobenil, napropamide) require activa- Effective weed control is possible by plowing, tion. They are most effective when applied to disking, clean cultivation or by establishing a moist soil and followed by irrigation. In vineyards competitive cover crop a year before planting. with drip irrigation systems, growers should take Weeds that are difficult to control under the trellis advantage of rainfall, applying just prior to or can be eliminated with appropriate cultivation during rains when possible. Soil organic matter techniques such as a grape hoe. Excessive mech- strongly influences the activity and safety of anical cultivation destroys soil organic matter and residual chemicals. Napropamide is the safest of the leads to a breakdown in soil structure. recommended chemicals on coarse, low organic matter soils. Dichlobenil can be used only at low Effective weed control under the trellis is possible rates on moderately coarse soils unless organic with mulch and a hand or mechanical grape hoe. matter levels are sufficiently high (3%) to prevent Hand weeding may be practical for small vine- leaching of the chemical. Diuron should be used yards if perennial weeds are eliminated the year only on heavier soils (silt, silt loam) with sufficient before planting. Hand weeding frequently leads to organic matter (>2%) or on loams and sandy loams disaster if it is not done on a routine, daily basis. with sufficient organic matter above 3%. Non- Effective weed control, using mechanical means, residual or foliar applied chemicals (glyphosate, requires repeat operations that can be labour paraquat) 8 are most effective on young, actively intensive, destroy organic matter, reduce water growing annual weeds. Perennial weeds are stage penetration and lead to trunk or root injury. dependent for control. Weeds under moisture Mulches stress are clearly more tolerant to glyphosate. Some weed species are tolerant of other herbi- Mulches consisting of a variety of materials can be cides. It is therefore useful to combine used to control weeds and moisture. Sawdust or complementary herbicides to broaden the spec- wood shavings can be used but avoid cedar prod- trum of weeds that can be controlled. The ucts. Grass clippings or hay could also be used, but, combination of a pre emergence residual herbicide these products contain seeds that may germinate. with a post-emergence herbicide is useful when Fertilizer applications may have to compensate at a knock down action of a post-emergence herbi- later date for the use of nitrogen by soil organisms to cide is needed in order to place the pre-emergence break down the organic matter in the mulch. herbicide on the soil. e.g. the use of glyphosate Organic materials must be at least 15 cm thick with dichlobinol, provides season-long control if around the vine and in the area where weeds are applied in late spring when weed growth is at the to be controlled to be effective against annual right stage for control by glyphosate. Other pre- weeds. emergence herbicides such as diuron or Control of perennial weeds should be done before planting since these are not easily controlled by 2010 Best Practices Guide for Grapes for British Columbia Growers 5-51 5 Crop Protection napronomide also provide good control if some situations. All vegetation is more easily used in this way. When using combinations of controlled when growing actively; i.e. under good herbicides, do not exceed the rate specified for fertility and soil moisture conditions. singly used herbicides. Always check the label for compatibility of a herbicide with another Young Non-Bearing Vines herbicide. FRONTIER (900 g/L dimethamid): Apply pre- Apply all materials in water volumes recommend- emergence to weed growth. Activate with irriga- ed on the product label, using pressures not tion/rain within 10 days. Do not harvest within 2 exceeding 300 kilopascals. Calibrate the weed sprayer years after application to newly planted or within 1 carefully. Avoid application to vine leaves. For year after application to second year plants. uniformity of application, use a boom-type sprayer. Established Vines Do not use equipment that is used for regular vineyard insect or disease spraying. Pre-emergence for grass and broadleaf weed control (Soil applied) Warning: Read the label instructions before handling. 2,4-D is very toxic to grape vines. Do not CASORON 4G (4% dichlobenil): Apply to apply this chemical in vineyards. If 2,4-D must be cool moist but unfrozen soil in late fall or spring used in areas close to vineyards it should be applied before weeds emerge. Do not apply if air tempera- before grape buds reach the woolly stage. tures are 10 degrees Celsius or more. Apply to dormant vines established for at least 2 years. Use Repeated yearly applications with residual herbi- lower rates on coarse sandy soils. cides may result in build-up of these chemicals in the soil and cause plant damage. DEVRINOL DF (50% napropamide): Apply in the fall through spring to unfrozen soil pre- There is no antidote for paraquat . Use extreme emergence to weed growth. Activation with suffi- precautions with this herbicide as even small doses cient irrigation or rainfall (~10-15mm) is essential taken orally have been fatal to humans. for good activity. Do not apply herbicides to vineyards when the KARMEX DF (80% diuron): Apply before soil is frozen. weeds emerge or tank mixed with GRAMOXONE after weed emergence. Use lower Prior to Planting a New Vineyard rates on sandy, coarse soils. Apply only to vineyards Serious injury to grape vines can occur if the land established for 3 years. that is to be planted to vineyard has been treated Post-Emergence for Grass and with residual herbicides such as diuron, simazine, Broadleaf Weeds dichlobenil or amitrole. Such land can be tested for herbicide residue the year before grapes are to be Trade Name(s): AIM EC planted by growing cucumbers in a soil sample. Common Name: carfentrazone-ethyl Normal germination and growth of this indicates . Group: 14 that the area is safe for grape growing. . Registered On: Grapes . Established perennial weeds such as quackgrass, Target Weeds: Very young broadleaf weeds orchard grass, field bindweed, etc., should be . Activity: Contact herbicide, not translocated eliminated the season prior to planting. This can be in plant. No residual activity. Non mobile in accomplished by use of either glyphosate or amitrole soil. applied at the appropriate stage of the problem . Use Suggestions: Alternative to other mate- vegetation followed by tillage approximately a week rials when rotating herbicides. later. The rates of application for each chemical will . Application: Post emergence to actively depend on the vegetation present. Please consult growing weeds. Less activity under dry con- labels for specific weeds. High rates are generally in ditions (drought or low humidity). Always order when attempting to obtain complete add an adjuvant (e.g. Agral 90). control of all vegetation present. However, excessive . Re-entry Interval: Not specified on label rates of amitrole can result in some residues in . Days to Harvest: 3 . Nurseries & New Plantings: Safe on crop

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Trade Name(s): CHATEAU UNACCEPTABLE CROP INJURY MAY OCCUR IF Common Name: flumioxazin THIS PRODUCT COMES INTO CONTACT WITH . Group: 14 NON-DORMANT STRUCTURES. Shielded applica- . Registered On: Grapes tions during this time period should not be made . Target Weeds: Selected grass & many with glyphosate, or products containing glypho- broadleaf weeds. Controls common sate. groundsel. . Activity: Does not leach or volatilize from Glyphosate products (ROUNDUP, TOUCH- soil, but does breakdown with microbial ac- DOWN, CREDIT etc.): Apply as a directed spray tivity, therefore residual control decreases avoiding leaves and green stems of grapevines. under conditions of higher microbial activity Repeat applications may be necessary since only (increased temperature, moisture, high or- emerged weeds will be controlled. Use on vines 3 ganic matter etc.). years old or more. . Use Suggestions: Alternative to other resid- . For annual weeds, use lower rates uals when rotating herbicides. . For quack grass and dandelions use higher rates . Application: Pre-emergence. Most effective when applied to bare weed-free soil. Re- . For perennial broadleaf weeds (Canada thistle, quires irrigation or rain to activate. Slow to field bindweed, etc.) use highest rates degrade when soils are cold, so can be ap- . For spot treatments with handheld/backpack plied in the late fall for spring control. On sprayers: Use 1 to 2 L/100L glyphosate apples protect spray boom with a hood or products in directed application shield after bud break. Do not apply within . For more information on water volumes, a 100 meters of pears unless pears are be- rates on specific weed species, timing of ap- tween harvest and 2 months prior to bud plication, time before harvest, removal of break. Protect/shield the trunks of apples suckers etc. consult detailed label information and pears less than one year old. included with each commercial glyphosate . Re-entry Interval: 12 hours product . Days to Harvest: 60 . Nurseries & New Plantings: Do not apply to GRAMOXONE  (200 g/l paraquat): Apply as vines less than 1 year old a directed spray avoiding grape leaves, fruit and . Do not apply to grapes established less than green bark. Use high water application volume 2 years. (1100 L/ha). KARMEX or DEVRINOL, at the . Do not apply to grapes that are not trellised rates listed above, may be tank mixed with or staked unless they are free standing. GRAMOXONE. . Do not apply within 60 days of harvest. IGNITE (150 g/L GLUFOSINATE . New plantings of “own-rooted varieties”, AMMONIUM): Apply as a directed spray to such as Concord, should be planted so that all annual weeds before 30 cm. high, avoiding grape roots are a minimum of 20 cm below the soil leaves, suckers and green bark. surface to be treated. In some situations, this may require hilling soil around newly planted Trade Name(s): IGNITE vines so that the settled depth of the hill will Common Name: glufosinate be 10-12.5 cm above the vineyard floor. . Group: 10 . Registered On: Grapes. Juice, Raisin and Wine Grapes – . Target Weeds: Non-selective – affects all Application Timing actively growing green plants; re-growth of . Do not apply during the period after bud- perennial species may occur. break through final harvest, unless using . Activity: Absorbed through foliage; minimal shielded application equipment and applica- translocation. No residual activity. tor can ensure spray drift will not come in . Use Suggestions: Alternative to glyphosate contact with crop fruit or foliage. if there is low pressure from difficult to control or established perennials weeds.

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IGNITE will knock back root suckers temperatures, poor moisture and low humid- without harming vines. ity speed of action may be reduced. Heavy . Application: Post emergence application. dew at time of application may reduce con- Avoid contact with leaves or green bark of trol of certain weed species. Rainfast in 4 crop, but suckers do not need to be re- hours. moved. Thorough coverage of the plant . Re-entry Interval: Not specified on label. tissue to be controlled is essential. Activity is . Days to Harvest: 40 influenced by environmental factors; at cool Table 5.7 Relative ratings for weed control with recommended herbicides in vineyards a,b

c

inate

s

Weeds phosate

y

chlobenil methamid

i i

Paraquat Gl D Napropamide Glufo D Diuron Annual broadleaved Buckwheat, wild F G E G G P E Chickweed, common E E E G E -- E Groundsel, common E E E P G -- E Lambs-quarters E E E G E G E Mallow, common F G E G G -- E Nightshade, annual E E E P E G E Pigweed E E E G E G E Shepherd’s-purse E E E P G P E Annual grasses E Barnyard grass G E E E G E G Bluegrass, annual E E E E E -- -- Brome, downy E E E E E -- E Foxtails E E G E G E E Perennial broadleaved Bindweed, field P G G P Gc P -- Cockle, white F E E P Gc P -- Dandelion G E E P Gc P -- Horsetail, field P P G P P P -- Nightshade, climbing P G G P P P P Poison ivy P G P P P P P Vetches P F G P Gc P P Perennial grasses Brome, mountain G G G P P P P Fescues G E E P G P P Quackgrass G E E P G P P Residual life (weeks) 0 0 10 8 0 8 10 Crop Safety Margin E E E E E E G

a. Rate of application of the chemicals listed are those used in the preceding text: commercial names are capitalized, common names are not and may represent more than one commercial product with the same active ingredient. b. These rates are given only to provide broad comparisons, and are subject to variations attributed to soil types, stage of vegetation at application, climatic conditions following application, different cultural practices, etc. c. Top growth control only; regrowth can be expected. Key: P = poor control (<50%); G = good control (90%); F = fair control (70%); E = excellent control (90 to 100%).

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Invasive Alien Weeds obstructing trails, and reducing aesthetics; and water quality and quantity by increased erosion Invasive plants are a serious threat to British and sedimentation. They also threaten protected Columbia’s agricultural industries and natural areas, wildlife, property values, public health and resources. safety, and the ecological health and diversity of The Invasive Plant Council of BC defines the the province’s natural environment. term "invasive plant" as any invasive alien plant Invasive species are the second largest species that has the potential to pose undesira- threat to our biodiversity, after direct loss of ble or detrimental impacts on humans, animals habitat. or ecosystems. Invasive plants have the capacity The B.C. Weed Control Act currently designates to establish quickly and easily on both disturbed forty-eight plant species as noxious weeds. and un-disturbed sites, and can cause wide- Currently, 21 weeds are listed as noxious weeds spread negative economic, social, and within all regions of the province. A further 27 environmental impacts. Many invasive plants are classified as noxious within the boundaries have been introduced to B.C. without their of specific regional districts. All of these species natural predators and pathogens that would are non-native plants that create problems in otherwise keep their populations in check in agriculture and/or natural habitats. For infor- their countries of origin. mation on identification of noxious weeds, refer Impacts associated with the introduction and to the BCMAL website at spread of invasive plants affect all agricultural www.al.gov.bc.ca/cropprot/weedguid/ industries in B.C. These unwanted invaders can The following tables list recently introduced negatively impact: agriculture by reducing crop invasive alien plants, affecting or potentially yield and quality and increasing management affecting grapes in B.C. The majority of invasive costs; rangelands by reducing forage quality and plant species and about 2/3 of pests established quantity; forestry operations by competing with in or threatening B.C. are species from outside seedlings for light, nutrients, and water; recrea- North America. tion opportunities by puncturing tires,

Recently Established Invasive Alien Plant Species in BC

Plant Distribution Suspected Year Control Products of Introduction Registered? Puncturevine Predominately Penticton south 1970’s Yes (Tribulus terrestris) into Okanagan Similkameen Valleys expanding north in valley Leafy Spurge North Okanagan with potential to 1970’s Yes (Euphorbia esula) move to South Okanagan Rush Skeletonweed North Okanagan Valley with 1990 Yes (Chondrilla juncea) potential to move to South Okanagan Perennial Pepperweed West Thompson region near 1992 Yes (Lepidium latifolium) Walachin and Windermere Lake, East Kootenays Field Scabious Boundary region and Thompson 1990 Yes (Knautia arvensis) region Common Bugloss Central Okanagan Valley, East 1990 Yes (Anchusa officinale) Kelowna area and Rock Creek Longspine sandbur South Okanagan Valley 1990’s Yes (Cenchrus longispinus) Wild-Four O’clock South Okanagan, Osoyoos area 1970’s Yes (Mirabilis nyctaginea)

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5.5 Wildlife Management Margaret Holm, Okanagan Similkameen Conservation Association Grape growing will inevitably bring producers into contact with wildlife. Some species (birds, rodents, deer, bear, etc.) can cause serious crop losses in the absence of properly applied management practices, while other species use vineyards as habitat without causing damage. There are many options for dealing with wildlife in vineyards. A useful source of information is available through the Infobasket portal of the BC Ministry of Agriculture & Lands (BCMAL) home page. Click on the Grapes Community, then Production and Processing/ Production/Plant Health Management/ Other Pests to access a list of Internet sites with relevant information on wildlife control. Also refer to the fact sheet “Farm Practices for Wildlife Control in the BC Interior” posted at http://www.agf.gov.bc.ca/resmgmt/fppa/refguide/activity/870218- 60_Wildlife_Damage_Interior_BC.pdf are quite effective in deterring a variety of wildlife Birds without harming them, including deer, raccoons, Starlings, robins, house finches and other bird rabbits and birds. For maximum effectiveness, species attack grapes. The European Starling, mount exploders or Av-Alarm speakers as high which causes the most serious damage, resemble a was possible to disperse the sound. It is usually blackbirds but with a stockier build, speckled best to alter the timing or location of these appearance, yellow bill and shorter tail. Juvenile noisemakers periodically, or the pests may be- starlings are grey-brown with grey bills. Starlings come accustomed to them. are a major factor in the decline of native bird Caution: Persons working within 50 m of an species and cause serious crop loss to small fruits Av Alarm speaker should wear ear protection. such as grapes. Starling Distress Calls A combination of two or three control methods is usually better than a single method in reducing crop Recorded distress calls have proven highly effec- damage. Begin bird control efforts as soon as birds tive in repelling starlings. Use a portable, begin to attack crops. Control methods may not automatic playback system to broadcast the be very effective once birds have established a distress calls. The components are a photocell, feeding pattern in a vineyard. on/off switch, a duration and interval timer, and a cassette tape deck with one or more speakers. Permits are required to kill any birds except European Starlings, crows, magpies, House Traps (English) Sparrows, and Rock Pigeons (domestic A modified Australian crow trap can catch large pigeons). Consult your local Conservation Officer numbers of starlings when supplied with appro- (Ministry of Environment) for further information. priate bait. Trapping may significantly reduce Provincial and federal legislation protects all local flocks of starlings in early summer. Howev- other migratory birds. er, trapping may be less effective in reducing Scare Tactics migratory flocks of starlings in late summer. Care must be taken to release any non-target Stationary “scare crows” such as human figures or bird species. For information on the Starling owl statues do not work. Flying hawk-shaped kites Control Program for the Okana- have more success. gan/Similkameen and to contact a local Yellow plastic tapes or streamers, strung between professional trapper, visit the BC Grapegrowers poles above the vines, act as a visual repellent Association website: and may be effective in keeping birds out of http://www.grapegrowers.bc.ca/ vineyards. Twist the tapes or streamers every 3 m starling.shtml or contact the office 1-877-762- and attach to poles 12 m apart. 4652 toll free. Noisemakers Nest box traps, which have been recently introduced, will trap any cavity nesting bird Cracker or whistler shells, propane exploders and including bluebirds, swallows, small owls, wood- electronic Av-Alarm or Phoenix Wailer Systems peckers and many other beneficial birds that

5-56 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection control insect and rodent pests. It is very im- maintain effectiveness. portant to check nest box traps daily and release non-target birds. (Note that it is illegal to trap non-pest bird species. This applies to all land tenures.) Nest removal: a less-labour intensive way of reducing the starling population is to erect nest boxes around your property, and simply remove the nest material every two weeks. Starlings will nest 2-3 times and produce as many as 15 young in a year. By repeatedly removing the material from the nest boxes you will prevent population increase. This also avoids the problem of trap- ping non-target species. Netting Netting is a very effective method of protecting grapes from birds. Plastic netting, installed on a system of poles and wires above the vines, can provide a bird-proof enclosure. Netting is a noiseless, non-toxic and nonlethal form of bird control which requires little maintenance once installed. Make sure to choose netting with the correct gauge for birds. Too-large a gauge will trap starlings inside which attract hawks and owls which get trapped and do more damage. Ensure anti-bird nets are draped and pegged correctly so that there are no slack points and openings. Lastly, check netting regularly to ensure that non-target birds are not trapped. For additional information, refer to the fact sheets:  “Netting for Bird Control in Grapes – A Decision- making Guide” posted at http://www.al.gov.bc.ca/cropprot/grape birdnet.pdf  “Installation of Bird Proof netting for Horticul- tural Crops “ posted at http://www.al.gov.bc.ca/resmgmt/publist /300Series/336100-1.pdf  “Integrated Bird Management” focuses on blueberries but has useful information for vineyard managers, posted at http://www.al.gov.bc.ca/cropprot/bir dipmplan.pdf Other Methods Other methods of damage reduction include the use of scarecrows and predator models, e.g. hawk shaped kites. Move such devices frequently to 2010 Best Practices Guide for Grapes for British Columbia Growers 5-57 5 Crop Protection

For further information on bird control meth- Place bait stations in areas where mice are likely ods, refer to the fact sheet “Suppliers of Bird to be found, e.g. near vines, fences and brush Control Materials and Equipment for B.C. Growers” piles. posted at http://www.algov.bc.ca/berries/ 1. Chlorophacinone ~ (many trade names for Publications/document/suppliers.pdf  0.005% baits) is a multiple dose anticoagulant Rodents rodenticide available in pellet bait formulations. Place in bait stations or broadcast evenly at label Information on the biology, damage and control rates. of rodents that may cause problems in vineyards is published in the booklet “Rodent Control on 2. Zinc phosphide ~ (many trade names for 2% Agricultural Land in British Columbia – Central and bait) is a single-dose rodenticide available in Southern Districts” available from the Kelowna cracked corn or pellet bait formulations. Place in BCMAL office. bait stations or broadcast evenly at label rates. Field mice (voles) prefer a habitat with abun- Pocket Gophers dant ground cover. They usually establish a system of surface runways and underground Pocket gophers live in underground burrows tunnels. Mice begin feeding on vines when cool and push up small mounds of excavated soil. weather reduces their summer food supply. Vine They can cause severe damage by feeding on roots injury can begin in late summer and continue below the surface. Apply recommended baits before through fall and winter. birth of the young in early to mid-April before alternative green host plants are available, thus Damage to roots is often worse than visible damage making the bait more attractive. Baiting after this above the ground. time may increase costs since the presence of Cultural Control alternative foods may decrease bait consumption affecting the level of control. 1. Mow the cover crop and remove tall weeds and grasses to discourage mice from breeding with- Apply 0.4% strychnine bait or 2% zinc phos- in the vineyards. phide bait using a hand probe, mechanical 2. Remove brush piles and other trash adjacent burrow builders, or bait stations. to vineyards to discourage mice from mi- Hand-Probes grating into the vineyards. Use a hand-probe when infestation is light or as 3. Destroy all vegetation at the base of vines with a clean-up operation between burrow-builder treat- herbicides or by cultivation to discourage ments. Probe opposite and about 30 cm from the mice from feeding on the bark. However, re- V-shaped indentation on the side of the mound. tain vegetation where snow cover may be The probe will drop about 5 to 10 cm when the inadequate to protect vines from cold tem- burrow has been located. Leave the probed hole perature change. open after baiting. 4. Place wire or plastic mouse guards around For information on the design and use of hand the base of vines, especially young vines, to ex- probes, refer to the fact sheet “Design and Use of clude mice. Mouse guards should extend to at Home-Made Hand Probe” on the BCMAL least 45 cm above soil level and 5 to 10 cm website at http://www.al.gov.bc.ca/ below. cropprot/handprobe.pdf. Rodenticides In field trials, commercially prepared 2% zinc Rodenticides may be attractive to cats, dogs or phosphide baits in pellet, whole grain or wildlife. Covered bait stations are a safer method of cracked corn formulations all gave excellent application than broadcasting. Bait stations will also control of pocket gophers. protect the contents from moisture deterioration; disappearance of bait will indicate the presence of mice. Bait stations can be constructed from old fluming, metal or plastic pipe, or pieces of wood. 5-58 2010 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection

Burrow-Builders Damage Prevention To build a proper burrow the soil must be damp and A properly built and maintained fencing is the most the Burrow Builder must be clean before using. Use effective and the only permanent long term a broomstick or iron bar, probe gopher runways bar solution to deer exclusion from vineyards. Scare to determine depth of the gopher runway. Set devices, repellents and shootings are short term, machine to the same depth. Make artificial runways 7 mainly ineffective deterrents to deer problems in m to 10 m apart encompassing the total infested area vineyards. and then cross the ends. Apply 0.4% strychnine Fencing ready-to-use (R.T.U.) bait  as per label instructions. Woven wire fences, although more expensive to Bait Stations construct than electric fences, provide the most Place the recommended amount of bait deep in each reliable protection from deer damage. These fences opened burrow in such a manner that the bait is not should be at least 2.4 m high with a 15 cm wire visible from the surface. Close the burrow without mesh. Secure the mesh close to the ground to burying or covering the bait and repeat treatment prevent deer from crawling underneath. Avoid of any opened burrows after one week. using barbed wire for the top of fencing which can injure both deer and non-target wildlife. The fact For above-ground use, place bait in a tamper sheet “Crop Protection and Wildlife Control Fences” is resistant bait station and replenish baits as posted on the BCMAL web site at necessary. Remove and bury any dead animals http://www.al.gov.bc.ca/resmgmt/publist/300 because they can present a significant poisoning Series/ 307250-1.pdf. hazard to predatory animals. Do not place bait above ground exposed to non-target species Electrified deer fences, although cheaper to build unless it is in a tamper resistant bait station. than woven wire fences, have higher mainte- nance costs, and in general are less cost-effective Traps than woven wire fences. Vertical fences are more Use pocket gopher traps (e.g. Guardian, Victor or effective than slanted designs. Electric fences Woodstream) where infestations are light or in should be 1.5 to 2.1 m high with 7 to 9 strands of areas where poisons cannot be used. Begin trap- high-tensile smooth wire at 20 to 30 cm spacing. ping in the spring when gophers are most active. It is important to use a high-voltage energizer It is important to correctly place the tunnel traps with this type of fence. in main tunnels. Open the tunnel using a hand For further information on electric fencing, refer to trowel or other small shovel and place two traps the fact sheet Crop Protection and Wildlife Control facing in opposite directions to intercept gophers Fences - Non-Electric and Electric Fence Designs in both directions. Use wire or light chain to posted at http://www.al.gov.bc.ca/resmgmt/ secure the trap to a stake to allow safe and easy removal of the carcass or trap. Make sure the publist/300Series/307250-1.pdf. Another useful opening is sealed to prevent light or air currents publication, Electric Fencing Manual, is available entering the tunnel. Check the trap once or twice from the Kelowna BC Ministry of Agriculture & daily. If no gophers are trapped after 3-4 days, Lands (BCMAL) office. relocate to another main tunnel. Always be vigilant The brochure Protecting Orchards from Deer will for gophers invading from bordering properties help growers to estimate the benefits and costs of and act promptly to prevent establishment. fencing. It is also available from the Kelowna BCMAL office. A complete listing of down- Deer loadable publications on fencing is found on the Deer and elk feed on grasses, shrubs, and vines. BCMAL web site http://www.al.gov.bc.ca/ They chew buds, spurs, shoots and leaves of all resmgmt/publist/Farm_Structures.htm#fencing. varieties of grapes. Damaged vines may never develop into commercially productive plants. Antler rubbing may break branches and remove bark.

2010 Best Practices Guide for Grapes for British Columbia Growers 5-59 5 Crop Protection

Bears tion Officer Service – Problem Animal Hotline (1-877-952-7277) for information on shooting or Bears can be a nuisance or cause extensive crop trapping nuisance bears. damage. In years when their native berry hosts have low production, orchards and vineyards Snakes become a favourite target of bears in the fall. Snakes are not a pest but are sometimes perceived Depending on the intensity of bear attack, vineyard as a threat to vineyard worker safety. Snakes are managers have tried many different methods to actually beneficial to grape growers because they keep bears out of their orchards such as nightly prey on mice and pocket gophers. Snakes often patrols to scare off bears using bird flares and forage at night and hide during the day. By provid- bangers, rubber bullets, or other scare tactics. ing cover areas (rock piles, shrubs or plywood) well Managers must weigh this approach against staff away from work areas and being aware of potential costs and safety. Properly constructed electric snake hiding spots, you can reduce encounters. fencing is the only proven effective method for Use a stick to probe irrigation valve boxes and protecting vineyards from bears. Information on lumber piles before reaching into a hidden spot. the construction of electric bear fencing is available Lastly, educate vineyard workers to identify rattle- from the fact sheet fact sheet “Crop Protection snakes and non-poisonous snakes. Snakes are and Wildlife Control Fences” posted on the protected by law. Provincial and federal laws BCMAL web site at http://www.al.gov.bc.ca/ make it an offence to harass or kill a snake. resmgmt/publist/300Series/307250-1.pdf. Also Snake identification posters and best management see “Shocking Solutions to Bear Conflicts – a practices are available at http://www.osca.org/ primer on electric fences at www.bearaware.bc.ca/ index.php/ecomanagement/ electric-fencing.htm

Contact the Ministry of Environment Conserva-

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5.6 Urban Issues As population increases farmers must become good  Take measures to reduce the noise impact if a communicators. Understanding and complying noisemaker is located less than 100 meters with local bylaws is important as well as discussions from an occupied dwelling or a place inhabit- with non-farming neighbours. Explaining normal ed by domestic animals on an adjoining farm procedures along with reasons for the property. practice and giving neighbours a chance to voice These should include directing the sound concerns may eliminate or minimize many away from the dwelling and using sound buff- misunderstandings. ers (such as hay bales). Do not use rotating noisemakers within 100 meters of an occu- Farm Practices Protection pied dwelling. (Right To Farm) Act  Do not use noisemakers prior to the onset of bird damage to crops (i.e., when birds are This act protects agricultural producers from legal not a threat). Remove noisemakers after the action as a consequence of nuisance complaints harvest is complete. surrounding agricultural operations and farming  Do not use noisemakers before 6:00 a.m. or activities. Protection against such complaints de- after 8:00 p.m. Pacific daylight saving time. pends upon the farm being operated in a ‘reasonable manner or in accordance with generally accept- Pesticides ed farm practices.” The farm must be located within the ALR, and the operation must comply Pesticide application may concern people living or with other relevant local, provincial, and federal pursuing activities near farms. Most pesticide legislation relating to the farm practice being complaints are about spray drift. Others may be challenged. (Also see Section 9.3, Farm Practices about improper pesticide storage, improper pesticide Protection Act) container disposal, or noise from sprayers.  Abide by provincial and federal legislation when Noise using, transporting, storing and disposing of Humming tapes, cracker or whistler shells, propane pesticides. exploders, Wyvern Walers (Phoenix Walers) and  Identify areas where drift could be a concern. electronic AV alarm systems, are effective in For example, property lines backing onto frightening birds out of orchards or vineyards. schools, care facilities, residential buildings, Before deciding to use this equipment, be aware walkways, etc. of the restrictions that may apply under municipal  Develop a drift reduction plan. Share the plan bylaws. Some local districts in B.C. have banned with concerned neighbours. the use of noisemakers entirely.  Use buffer zones to prevent spray drift into The use of these devices may result in complaints sensitive areas. from neighbours, particularly where farms are  Adjust, maintain and calibrate your sprayer at located adjacent to residential areas. The Munici- least once a year. pality of Surrey, for example, has already banned  Apply pesticides when weather conditions the use of noisemakers, and other municipalities minimize the possibility of drift. have placed restrictions on their use. Check the  For more tips on reducing spray drift, please bylaws of your local municipality before using any refer to the publication Orchard Spray Drift noisemaker. To minimize noise disturbance to Management (http://www.al.gov.bc.ca/ neighbours, adhere to the following guidelines resmgmt/publist/200series/234006-2.pdf). for the use of propane exploders:  Also see: Neighbour Relations and Pesticides  Do not establish more than one noisemaker http://www.al.gov.bc.ca/pesticides/a_8.htm per two hectares of crops. Empathy by all concerned along with con-  Do not set off any noisemaker more than once tinued communication and valid farming every three minutes. activities will help minimize complaints as well as the production of local by-laws to control farming practice. 2010 Best Practices Guide for Grapes for British Columbia Growers 5-61