5 Crop Protection

5.3 Insect & Mite Pests of Grape Revised February, 2015

D. Thomas Lowery, AAFC-PARC, Summerland Biological Control of Insects and (Graphics by Robyn DeYoung) Mites

Insect and mite pests of grapes are attacked by Fewer insect and mite pests attack grapes grown many species of beneficial organisms, including in British Columbia compared with many other bacterial and viral diseases, spiders, insect major grape producing regions, which allows for predators, predacious mites, and vertebrates a ‘softer’ approach to pest management that such as toads and birds. Maintaining and preserves beneficial insects and predacious enhancing numbers of these natural ene- mites that help regulate secondary pests such as mies of grape pests forms the cornerstone of spider mites and grape mealybug. Adoption of a successful IPM program. Healthy popula- integrated pest management (IPM) practic- tions of predators and parasites prevent es that minimize the use of chemical sprays outbreaks of secondary pests and reduce the can also help reduce production costs, numbers of sprays required for the control of reduce human exposure to insecticides, and primary pests such as leafhoppers and climbing preserve the local environment. Insect and Mite cutworm. Pests of Grape in British Columbia (Lowery et al., 2014), a companion publication contains colour Beneficial organisms can be preserved or photographs of many of the pests outlined in enhanced in several ways. The negative impact this chapter of the production guide. In the of pesticides can be minimized by spraying only following descriptions of grapevine pests, when and where required. Monitoring of pest numbers and letters indicated in parentheses numbers will often indicate that only a small refer to the pages and plates of the correspond- portion of a vineyard requires chemical treat- ing photo guide. Additional sources for ment. Selecting the most appropriate spray information on insect and mite pests of grapes material will help reduce damage to non-target are listed at the end of this section. organisms. Compared with broad-spectrum insecticides that are often more toxic to benefi- Integrated Pest Management cial insects than the pests they are intended to control, insecticides that are less damaging to IPM utilizes a number of principles and practic- beneficial insects and predacious mites (e.g. es to manage pest populations, including AltacorTM) should be chosen whenever possible. biological, cultural, and physical control meth- Malathion is considered to be less damaging to ods. Insecticides remain an essential beneficial insects and mites than other insecti- component of an IPM program, but they are cides in the same class (organophosphates), and applied as a last resort only when monitor- carbaryl (Sevin XLRTM) can be used at a low ing has shown that pest numbers are likely rate when the target is the susceptible Virginia to exceed the economic threshold. When creeper leafhopper rather than the more re- insecticides are required, their selectivity, persis- sistant western grape leafhopper. Other tence, and effects on non-target organisms materials, such as the microbial insecticide Dipel should be considered. Some have minimal (B.t.), are highly selective and require that the effects on beneficial insects and predacious pest consumes the treated plant part, reducing mites, while others cause significant reductions toxicity to most non-target species. As listed in in natural enemy populations. A brief descrip- the BCMAL fact sheet ‘Pest Control Products tion and a few examples of the various Recommended for Use on Grapes in British Columbia’, components of a grape IPM program are (http://www.agf.gov.bc.ca/cropprot/grapeipm outlined below. For additional information, /grape_pesticides.pdf), all of the Class 4 (neon- refer to the Integrated Pest Management section icotinoid) insecticides (AssailTM, ClutchTM, (5.1) of this guide. CloserTM) combined should not be applied more than twice per season to avoid mite outbreaks. Best Practices Guide for Grapes for British Columbia Growers 5.3-1 5 Crop Protection

These materials are listed as toxic to bees. The water and nutrients. Recent research in Califor- Class 3 pyrethroids (PounceTM, AmbushTM, nia has shown that deficit irrigation from berry RipcordTM) and natural pyrethrins (PyganicTM) set to veraison reduced leafhopper numbers by are toxic to most beneficial insects, but they more than 60%. The modest reduction in yield, persist in the environment for only a short time. around 15%, was more than offset by a signifi- cant improvement in wine quality. In addition, Thoughtful choice of management practices can berries were smaller and exposed to more light also help preserve beneficial insects. Mowing and air and pruning costs were slightly lower. less often and mowing only alternate rows at The presence of broadleaf weeds in and be- one time are simple and cost effective ways to tween vine rows is associated with lower levels increase populations of most natural enemies. of cutworm damage. In spring, when possible Adults of many beneficial species feed on nectar avoid controlling shepherd’s purse and other of flowering plants that also serve as hosts for weeds in the vine row until after buds have alternate prey species. As a general rule, in- broken, as removal of these alternate sources of creased plant diversity is associated with greater food forces cutworm larvae to feed more on the numbers of beneficial insects. A diversity of buds of grapes. plants can be provided in the vineyard in mixed ground covers, or in hedgerows and uncultivat- ed areas within or adjacent to the vineyard. Pruning Pruning can be altered to help reduce damage Cultural and Physical Controls from cutworm larvae. Slightly more buds can be Vine Vigour and Resistance left on vines to compensate for damage, but this will require the removal of more unwanted For most crops, varieties can be selected that shoots later in the season. Some growers delay are partially or wholly resistant to one or more suckering and shoot thinning to divert some pests and diseases. Except for rootstocks that leafhopper feeding and egg-laying to these are resistant to grape phylloxera or nematodes, unwanted plant parts. Thinning of the canopy this is generally not a viable option for wine by shoot removal, shoot positioning, and grapes. Most desirable wine grape varieties removal of basal leaves improves air flow and possess little resistance to foliar feeding pests. light penetration, which is important for the Vine vigour does, however, influence insect and management of diseases as well as insects. mite numbers. Leafhoppers and grape mealy- bug, for example, will reach significantly higher Leafhoppers and erineum or blister mite infest numbers on overly vigorous vines as they prefer the first leaves that emerge in spring, and these the darker, sheltered environment and elevated lower leaves can be removed in June to reduce humidity that excessive vine growth provides. numbers of these pests. A study conducted in Insects developing on these plants survive commercial British Columbia vineyards showed better and grow faster due to better nutrition, that removal of basal leaves in June rather than softer tissues, and changes in concentrations of August reduced numbers of leafhoppers and the secondary plant compounds. At the other incidence of bunch rot. Vine vigour and berry extreme, chlorotic vines with low vigour are less size were reduced only slightly and there was able to tolerate insect feeding damage and are little effect on ripening or quality of fruit. Early more susceptible to attack by hard scale insects season leaf removal might not be suitable for and wood boring beetles. Fortunately, the stressed vines or vines on sandy sites with optimum balance in vine growth that results intense heat and light where fruit can become in the highest quality wines is also best for sunburned. As for late season removal, partial minimizing the growth of pest populations. removal of leaves from only the shaded sides of the vines might be more suitable in these areas. Management of vine vigour is an important consideration in the establishment of a new Physical controls vineyard and is discussed elsewhere. After vines are established, growth is controlled by pruning, For some vineyards, the use of yellow sticky cropping, selection and management of appro- tape applied below the cordon in spring can be priate ground-cover plants, and the provision of an economical way to manage leafhoppers. 5.3-2 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection

Although costly, this physical control method that begin laying eggs at this time. Thrips preserves beneficial insects and reduces or damage table grapes from 75% bloom to fruit eliminates the need for additional insecticides set, and if scale or mealybug were noted earlier, later in the season. Use of yellow sticky tape is sprays can be timed based on the presence of most practical in vineyards where damaging crawlers. The need to spray for first generation numbers of leafhoppers occur in small, isolated leafhoppers should be based on monitoring for areas or on a few outer rows of the vineyard. small nymphs from mid June to mid July, while Other physical controls include pruning out of second generation nymphs will reach their peak canes infested with scale insects and application usually after the first week of August. In sum- of barriers to prevent climbing cutworm from mer, the presence of soft scale and mealybug is reaching developing buds. often betrayed by the presence of honeydew and attendant ants. Throughout summer, Monitoring and Chemical Controls monitor for thrips, spider mites and grape leaf Insecticides should only be applied when rust mite. 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 Begin monitoring for spotted wing drosophila grapevines can tolerate moderate amounts of when fruit begins to ripen. leaf damage and small numbers of pests may have little or no effect on vine growth and If chemical control of a pest is indicated, refer yields. Even when pests have reached damaging to the fact sheet Pest Control Products Recommended levels sprays should be withheld until the for Use on Grapes in British Columbia, posted at economic benefit of treating the crop exceeds http://www.agf.gov.bc.ca/cropprot/grapeipm/ the cost of controlling the pest, including grape_pesticides.pdf for suitable spray materials, possible disruption of beneficial insects. In or consult with private consultants or your other words, sprays should only be applied chemical supplier. It is the legal responsibility when pest populations reach the economic of pesticide applicators to follow the label injury level where control of the pest pro- instructions and apply only those products vides an economic return to the grower. that are registered for use on grapes. The British Columbia Wine Grape Council and Thresholds for grape pests are currently based the authors of these pest management mostly on visual inspections. Yellow sticky cards sections do not assume legal responsibility can be useful indicators of general population for the misuse of any pesticides mentioned trends and pest developmental stages. Care in this guide. For grapes or wines destined for should be taken to conduct a thorough inspec- export, check to ensure that the importing tion that takes into account the variable nature country has maximum residue levels (MRL) for of the crop and the uneven distribution of most the control products. Observe the days to grape pests. Particular attention should be given harvest interval (PHI = pre-harvest interval) to to field edges and to areas that have experienced avoid exceeding the MRL. Producers of organic damage previously. The use of double sided grapes should also refer to the list of acceptable clear tape applied around shoots or the vine products and consult with an organic growers’ cordon can be used to assist with timing of organization. sprays for the control of the young motile stages of grape mealybug and soft scale insects. Grapevines need to be monitored for pests Major Pests of Grape throughout most of the year. It is easier to spot scale infestations during pruning or early in The major insect and mite pests of grapes spring before leaves are present. Grapes need to grown in BC are cutworm larvae that attack be visually inspected frequently in spring when buds in spring, leafhoppers that feed on leaves unopened buds are susceptible to cutworm throughout the summer, wasps that eat ripe damage. When the first leaves have fully ex- fruit and annoy or sting workers, and mealybug panded, watch for early infestations of erineum and soft scale that transmit grapevine viruses. mite and note the presence of leafhopper adults Grape phylloxera is an important pest of grapes Best Practices Guide for Grapes for British Columbia Growers 5.3-3 5 Crop Protection worldwide but it occurs in only a few scattered Identification locations in the southern interior. Other than wasps, these pests are largely absent from the Adults of both species are similar in appearance, Lower Mainland and Vancouver Island. In nearly ½ cm in length with reddish-brown addition to the major pests listed above, pro- markings on a pale white or yellowish back- ducers of table grapes need to worry about ground. Adult WGLH (2d in photographic spotted wing drosophila, earwigs and scarring of guide) can be distinguished by their pale eyes fruit by thrips. Earwigs do not cause direct and irregular reddish-orange markings on a damage to grapes but are considered a contami- whitish background. VCLH (2a) have reddish- nant by many vendors of table grapes. brown eyes and a more regular reddish-brown zigzag pattern on the wings. The background Proper management of these primary pests is body colour is pale yellow to light brownish- the most important consideration in an IPM yellow, producing an overall darker appearance. program. Grape pests and the damage they Adult leafhoppers are best identified on yellow cause needs to be recognized so that popula- sticky cards placed in outer vineyard rows tions can be monitored at the appropriate time during late April and May that can be inspected of the season to determine if insecticide applica- with the aid of a hand lens or magnifying glass. tions are warranted. Avoiding unnecessary sprays will help prevent outbreaks of secondary pests that are normally regulated by an assort- ment of predators and parasites. Leafhoppers Virginia creeper leafhopper, Erythroneura ziczac Walsh Western grape leafhopper, E. elegantula Osborn

In addition to the widespread Virginia creeper leafhopper (VCLH), the western grape leafhop- per (WGLH) that was initially found infesting grapes on the east side of the Okanagan Valley from the north end of Penticton south to the U.S. border has now spread to the west side of the valley and as far north as Naramata and Peachland. 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, Immature WGLH (nymphs) (2e) are distin- resulting in a rapid resurgence in pest numbers guished by their pale white colour, lack of and outbreaks of thrips, mites, and mealybugs. pigmentation in the eyes, and the presence of one to three pairs of pale indistinct yellow spots Experience has shown that WGLH numbers are on the thoracic segments of larger nymphs. low in organic vineyards; damaging populations VCLH nymphs (2b) have reddish-brown eyes in conventional vineyards generally result from and a pale yellowish body colour. Larger VCLH repeated sprays of insecticides that do not nymphs develop a pair of dark reddish-brown control this species but damage numbers of the spots on the first body segment behind the head egg parasite, Anagrus erythroneurae. Successful and a pair of reddish-orange spots on the other control of leafhoppers relies on proper monitor- two thoracic segments. Nymphs can be identi- ing of numbers throughout the vineyard and the fied feeding on the undersides of fully expanded judicious use of insecticides in order to preserve leaves that show signs of feeding damage beneficial insects and spiders. (stippling). 5.3-4 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection Life Cycle and Damage late well with subsequent nymph counts. It is helpful to note where large numbers of adults The biology and life cycles of the two species occur early in the season, as these areas should are similar. There are two generations each year. be observed more closely later on. Adults of both species spend the winter in leaf litter or under plant debris in the vineyard or in Adults are more tolerant of insecticides and nearby vegetation. Adults emerge on warm sprays should be targeted against the wingless spring days to feed on a wide variety of plants, immature stages. Depending on the location of moving to grape, Virginia creeper and Boston the vineyard, monitoring of 1st generation ivy when the first leaves appear. The overwin- nymphs should begin in early to mid-June. tered females deposit eggs in the leaf tissue on Monitor populations by counting numbers of the undersides of fully expanded leaves during nymphs on the lower surfaces of 5-10 leaves in May and June. The small, flattened opaque eggs at least 5 locations per block or variety. Select (2c) are deposited side by side, usually in small older bottom leaves up to just above the fruiting groups of around two to six for the VCLH and zone. In order to prevent damage to any vines, singly for the WGLH. Nymphs of this 1st sampling should focus on more heavily infested generation hatch mainly from mid-June to the areas. Sample from the north and east sides of end of July. There are five nymphal stages. rows where more nymphs will be found and Winged adults that appear during July and focus on the leaf zone showing signs of feeding August lay eggs that develop throughout the fall damage. Infestation levels are based on the into overwintering adults. The WGLH develops average number of nymphs per leaf. more slowly than the VCLH and nymphs will Established grapevines are tolerant of leafhop- occur later into the year. per damage during the first half of the season Both adults and nymphs feed by piercing when growth is rapid. Because of this, there are individual leaf cells and sucking out the con- no established thresholds for 1st generation tents. Light infestations cause leaves to appear nymphs. The threshold of approximately 20-25 stippled (2f) due to the death of individual cells. nymphs per leaf established for the 2nd genera- Heavier feeding results in brown, dried leaves tion in late summer can also be used as an that fall prematurely. Some studies have shown approximate threshold for early summer sprays. that light infestations can actually improve the A higher threshold can be used for 1st genera- quality of grapes on vines that are overly vigor- tion nymphs if healthy populations of predators ous, but excessive feeding reduces the are present and a high rate of parasitism is likely. photosynthetic activity of the vines, resulting in Control of 1st generation nymphs is often more delayed maturity, yield losses, and reduced fruit effective as there is less foliage, nymphs are quality. Large infestations deplete carbohydrate confined to leaves around the fruiting zone, and stores and weaken the vines. Light coloured sprays can be directed in a narrow band to varieties can become spotted and unsightly with ensure good coverage. It is recommended, excrement, which is a particular concern for therefore, to treat vineyards with a history of table grapes (2g). Adult leafhoppers are also an heavy leafhopper damage during this time. Soap annoyance to pickers during harvest. sprays are much more effective when targeted against 1st generation nymphs when approxi- Monitoring and Spray Thresholds mately 80% of the eggs have hatched. Egg hatch 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 prefer vigorous vines and those that vineyards that are managed organically should leaf out earliest. Monitoring numbers of adults be reduced considerably, perhaps to around 5- captured in spring on yellow sticky cards can 10 nymphs per leaf. help determine relative infestation levels, but because some eggs fail to develop and predation Second generation nymphs should be moni- rates are variable, these numbers do not corre- tored beginning in August in a manner similar to that outlined above. Greater attention should Best Practices Guide for Grapes for British Columbia Growers 5.3-5 5 Crop Protection be paid to vines in the center of the field, Cultural and Physical Control however, as infestations will have spread from field edges and ‘hot spots’ to a larger area of the Leafhoppers prefer excessively vigorous plants vineyard. Nymph counts should be collected and vines should be irrigated and fertilized to initially every other week and then weekly when maintain moderate growth best suited to the the time for spraying approaches. For wine production of high quality wine grapes. The use grapes, an approximate threshold of 20-25 of yellow sticky tape applied below the cordon nymphs per leaf on the more heavily infest- in spring can be an economical way to manage ed leaves can be used as a rough guideline. leafhoppers in some vineyards. Although costly, This is an average value based on counts from this method helps preserve beneficial insects several leaves as outlined above. Again, for a and reduces or eliminates the need for addition- particular area of the vineyard, collect 5-10 al insecticides later in the season. The use of leaves from at least 5 areas and calculate the sticky tape is likely not cost effective for large average number of nymphs per leaf. For 2nd areas but it can be a useful method where generation nymphs, sample leaves from the infestations are confined to small areas or to the middle of the canopy above the fruiting zone edges of vineyards. and from the north or east sides of vines where A study conducted by PARC researchers begin- numbers will be higher. Leafhoppers will be ning in 2001 demonstrated that removal of basal distributed unevenly in a vineyard and it is leaves during the 2nd to 3rd weeks of June when important to sample thoroughly to determine most eggs of the 1st generation have been laid which areas require treatment. Although the effectively reduced numbers of leafhoppers and above threshold provides a rough guideline, an the incidence of bunch rots. No significant acceptable spray threshold should be deter- differences were noted in fruit quality other mined by individual growers based on their past than a slight reduction in yield and berry size, experience and additional factors such as vine but it is recommended that growers first assess vigour and numbers of beneficial insects. the effectiveness of early leaf removal on only a few rows of each variety. Removal of leaves Biological Control around the fruiting zone at any time of the season might not be suitable for stressed vines Predators, such as birds and spiders, and para- or on sites with intense heat and light that might sites attack leafhopper eggs, nymphs or adults. lead to sunburn. However, sunburn is less likely Although occasionally contaminating table to occur following early removal of leaves (June) grapes, earwigs consume a large number of as compared to late (August) leaf stripping. leafhopper eggs, leaving behind small, shallow Exposure to more light and air causes develop- scraped areas on the undersides of leaves. A ing berries to develop thicker skins and more small egg parasite, Anagrus daanei, helps control wax, and the subsequent growth of lateral VCLH in some vineyards where parasitism rates shoots will provide some shading. This practice can approach nearly 100% late in the season. A is labour intensive but growers often remove different parasite, A. erythroneurae, parasitizes these leaves later in the season in order to eggs of the WGLH and is largely responsible for improve fruit quality. Removing basal leaves too the control of this pest. A. erythroneurae overwin- early will simply force leafhoppers to deposit ters in eggs of the rose leafhopper on wild and their eggs higher up the vine and might inhibit domestic roses, apple, blackberry and plum. In bud initiation required for the following year. early spring this parasite utilizes eggs of a leafhopper found on a wide range of mints, including catnip and catmint. Most vineyards Chemical Control have good numbers of A. erythroneurae and Some insecticides registered for leafhopper outbreaks of WGLH are largely associated control are ineffective for the WGLH and it is with sprays of insecticides that do not important to determine if this species is present control this leafhopper but are toxic to the in your vineyard. If only the VCLH is present, parasite. Excessive rates or unnecessary sprays natural enemies should be preserved by applying of insecticides will also reduce numbers of other the lowest effective rate only to areas where the beneficial insects and spiders. pest has exceeded the threshold level. To date,

5.3-6 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection this species has not yet developed resistance to and they have more pronounced triangular insecticides. shaped heads (2h). The large nymphs appear a uniform brown. Infestations are generally When monitoring of leafhopper nymphs indi- restricted to vines growing in close proximity to cates that insecticide sprays are required, apply the preferred host plants after which these one of the materials listed in Pest Control Products species are named. There are no chemicals Recommended for Use on Grapes in British Columbia, registered for the control of sharpshooters in posted at http://www.agf.gov.bc.ca/cropprot/ British Columbia, but sprays applied for the grapeipm/grape_pesticides.pdf. control of leafhoppers should also help control It is often sufficient to spray small areas or these species. treat only the perimeter of the vineyard. Spraying in this fashion is more economical and Climbing Cutworms helps preserve beneficial insects. Although a Lepidoptera: Noctuidae reduced rate (640 ml/ha) of carbaryl (Sevin XLR PlusTM) to control VCLH is suggested to To date, over 20 species of cutworm have been help preserve beneficial insects, full label rates identified feeding on the buds of grapevines in will provide only moderate control of the more the southern interior of British Columbia; the resistant WGLH. Malathion is currently regis- three most common species being Barnes’ (= tered for the control of leafhoppers on well-marked) climbing cutworm, Abagrotis orbis grapevines but it is largely ineffective against the (Grote), Reed’s dart, A. reedi Buckett, and WGLH. AssailTM (acetamiprid) has been shown Abagrotis nefascia (Smith). The W-marked cut- to be repellent to adults and will cause them to worm, Spaelotis clandestina, old man dart, move to unsprayed portions of the vineyard. Abagrotis vetusta, and dark-sided cutworm, Euxoa Sprays should be targeted against small nymphs. messoria, can also cause considerable damage in Although AssailTM is less damaging to some certain locations in some years and there is beneficial insects compared with many broad- growing concern about a new invasive cutworm spectrum insecticides, it is toxic to predacious pest, the lesser yellow underwing, Noctua comes, thrips and can cause spider mite numbers to that continues to increase in numbers and increase. Leafhopper numbers will be sup- distribution since it was first found in the pressed with sprays of SurroundTM (kaolin clay) Okanagan in 2001. Cutworm feeding damage or from sprays of PureSpray GreenTM spray oil to the buds of grapes can vary greatly be- or Safer’s Insecticidal SoapTM applied for the tween years and locations and it is not control of mites and grape mealybug. Apply uncommon for only parts of vineyards to be soap and oil in high volume sprays and ensure seriously damaged. Because populations that the bottom leaf surfaces are covered thor- fluctuate greatly and monitoring of cutworm oughly. larvae is difficult, damage can be considerable.

Recent research at AAFC-PARC Summerland Identification has shown that some newer fungicides and surfactants are repellent to adult leafhoppers Cutworm larvae are and their use might eliminate the need for smooth, soft, thick- additional sprays. Increased movement of adult bodied caterpillars leafhoppers within and between vineyards measuring about 4 requires greater vigilance. to 5 cm when fully grown (1a, 1b). Sharpshooters Larvae typically live in the soil or under debris and will curl up when The poplar sharpshooter, Neokolla heiroglyphica disturbed or handled. Depending on the species, (Say), and the willow (=purple) sharpshooter, larvae are most often light to dark grey or N. confluens (Uhler), occasionally infest the brown and marked with spots and stripes. shoots of grapevines in sufficient number to Adults are drab moths with bodies around 2 to warrant control. The dark coloured adults 2.5 cm long (1a, insert). The hind wings, which appear oversized in relation to the other leaf- are sometimes distinctly marked, are usually hoppers found on grapes in British Columbia lighter in colour than the forewings. The lesser Best Practices Guide for Grapes for British Columbia Growers 5.3-7 5 Crop Protection yellow underwing moth is most noticeable by in pasture are prone to damage and larvae are the bright orange hind wings that are edged in often sheltered and somewhat confined within black (1b). Cutworm moths are active at night the protective milk cartons or sleeves placed and rest during the day in sheltered locations. around new vines. Loss of buds on new vines 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. Cutworm that feed on grapes spend the winter as small larvae in the soil or under fallen leaves Significant amounts of damage can occur over or debris. When the weather warms in spring a period of two or three days when the nights they resume feeding and complete their devel- remain warm and it is especially important to opment. Damage to grapes occurs during this monitor for damaged buds frequently during time when the rapidly growing larvae feed on this time. At other times it is usually sufficient developing buds and new shoots. Moths emerge to monitor vines weekly or twice weekly until in June and remain in a quiescent state through- shoots have elongated. An accurate threshold out the summer until fall when they become based on the degree of bud damage is difficult sexually mature and begin laying eggs that hatch to determine, as it is influenced by the variety, into the overwintering larvae. There is a single training system, method of pruning, presence generation each year. of predators and parasites, and tolerance level of the individual vineyard manager. Damage to grape buds varies with the size of the cutworm larvae. Small larvae will often Suggested economic thresholds provided by burrow into a bud, creating nearly circular holes growers range from virtually zero to over 15%; that were previously attributed to feeding by a value around 3% bud loss is likely for most adult click beetles (1c). Larger cutworm larvae vinifera varieties. Establishment of spray will chew large, sometimes ragged, holes and thresholds should also consider the potential remove a large portion or all of the bud. Feed- for secondary pest outbreaks that will require ing on new, tender shoots can cause the shoots additional insecticide sprays later in the season. to break or wilt (1d). Larvae climb the vine trunks or support posts each night and return to Biological Control the soil during the day, or they will find refuge Cutworm eggs are consumed by various preda- under loose bark of older vines. tors and are parasitized by small wasps. Larvae are eaten by ground beetles, hunting spiders and Monitoring and Spray Thresholds birds, and are parasitized by wasps and flies. Cutworm numbers vary over time and between Fungal and bacterial diseases that attack cut- and often within vineyards. Some vineyards worm larvae are common, particularly when rarely experience significant levels of cutworm conditions are cool and wet. The combined feeding damage while others are damaged effect of these natural controls is to eliminate yearly. Mild, dry conditions during the winter most cutworm eggs and larvae. Of the 300 or increase survival rates, while outbreaks of viral more eggs laid by a female moth, only a few and other diseases that affect cutworms can survive to become reproductive adults. Even so, reduce numbers to low levels. Cutworm damage damage resulting from the few remaining larvae is often higher in areas with dry gravelly or can be considerable. sandy soils that do not support good stands of broadleaf weeds, with drip irrigation systems, or Cultural Control as a result of weeds being controlled too early in Broadleaf weeds growing in the vine rows the spring before shoots have elongated. Main- should not be controlled in spring until taining a record of previous damage can help shoots have elongated and the first leaves suggest which areas need to be monitored most have expanded. Damage is generally much closely and where damage is likely to occur first, lower in vineyards with mixed ground cover but bud damage needs to be assessed through- vegetation and where broadleaf weeds, particu- out the vineyard. larly winter annual mustards such as shepherd’s New vines planted in untreated land previously purse, Capsella bursa-pastoris, are present in the 5.3-8 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection vine rows and drive rows in spring. Larvae are Grape Phylloxera usually more common in areas with well-drained Daktulosphaira vitifoliae (Fitch) sandy or sandy-loam soils that support fewer broadleaf weeds. Diseases that infect larvae are Grape phylloxera (Homoptera: Phylloxeridae), also likely to be more prevalent in soils that native to eastern North America, is a type of retain moisture. Control of vegetation with aphid found on the roots of grapes or in galls herbicides or repeated discing during the fall formed on the leaves of wild grapes or hybrid prior to the establishment of a new vineyard will varieties. European vinifera varieties are particu- help reduce damage to newly-planted vines. larly susceptible to this pest and the accidental introduction of phylloxera to California, Eu- Cutworm damage is partially related to pruning rope, and elsewhere initially devastated these practices and grape varieties. Vines with a industries. Management of phylloxera with greater number of retained buds in spring will insecticides was not successful and the wine suffer marginally less damage, but there will be grape industry was only rescued with the devel- added costs related to removal of extra shoots. opment of resistant rootstocks derived from Some grape varieties will produce fruit on American Vitis species or hybrids between these secondary shoots, but yields will still be reduced and susceptible V. vinifera. Phylloxera were first and ripening can be delayed or uneven. identified in the Penticton area in 1961; infesta- tions currently are scattered and at relatively low Chemical Control levels in British Columbia vineyards, mostly due Sprays of the pyrethroid insecticide PounceTM to the use of resistant rootstocks and the failure (permethrin) should be directed to the soil at of this pest to thrive on sandy soils. the base of vines, to vine trunks, and to support As early as 1914 it was recognized that grape posts so that larvae contact the insecticide while phylloxera consisted of several distinct biotypes moving from the soil to the canopy. Do not or races. Biotypes differ in their ability to form cultivate or disturb the soil for several days after galls on the leaves of certain cultivars, in the treatment. For young vines, sprays should be degree of feeding damage caused to roots, and directed into the milk cartons or other protec- their propensity to form sexual or winged tive structures applied around newly planted forms. One study demonstrated that rootstocks vines. Avoid spraying insecticides unneces- with unsatisfactory levels of resistance to phyl- sarily, as these are very damaging to loxera in Europe and South Africa were suitable beneficial insects and can result in out- for California, Australia and New Zealand. Loss breaks of secondary pests later in the of resistance can also occur over time as new season. biotypes of phylloxera arise. AltacorTM (rynaxypyr) was recently registered for cutworms on grapes. Rapid cessation of Identification feeding and toxicity result largely through Adults are very small, usually wingless, and less ingestion and sprays should be directed to the than 1mm long and half as wide (4a). Colour developing buds. AltacorTM is considered a varies from pale green, yellowish-green or light reduced–risk material due to its greater selectivi- brown on vigorous roots, to brown or orange- ty and reduced toxicity to non-target organisms. brown on declining roots; as adults age they Follow the label instructions and wear appropri- become a darker brown or even purplish- ate protective clothing as for all pesticides. The brown. Winged sexual forms are rare in British list of materials registered for cutworm control Columbia and the northwestern United States is likely to change before the next printing of and they do not appear able to reproduce this guide and it is important to refer to the sexually on vinifera grapes. Leaf galls are formed most recent edition of Pest Control Products on French-American hybrids, Concord juice Recommended for Use on Grapes in British Columbia grapes and some rootstocks. The relatively small for appropriate registered materials. galls on the undersides of leaves are green and roughly circular (4c). These should not be confused with the white or brown fuzzy galls of variable sizes and shapes formed on the under- Best Practices Guide for Grapes for British Columbia Growers 5.3-9 5 Crop Protection sides of leaves by erineum (leaf blister) mite Insecticide treatments were previously not (4d). effective and there are no spray thresholds for 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 hatched nymphs leave the roots through cracks Biological control of phylloxera has not been in the soil and migrate to the roots of nearby studied in detail. A number of generalist preda- vines. These small crawlers have been known to tors are known to feed on phylloxera in leaf climb vine trunks and be blown on the wind for galls. In Ontario, larvae of two species of some distance. In late summer a portion of the predaceous flies were commonly associated with nymphs develop into winged females (alates) leaf galls. Predaceous soil-dwelling carabid that leave the soil and fly to other vines where beetles undoubtedly feed on phylloxera infesting they lay eggs in the crevices in the bark that roots, and because they do not produce honey- hatch into males and females. After mating, dew, ants are likely to feed on phylloxera rather females produce a single larger overwintering than protect and ‘milk’ them as they do aphids. egg. In spring the eggs hatch into females that Although natural enemies are unable to effec- feed on developing leaves and produce galls on tively control populations of phylloxera, susceptible varieties. Nymphs produced in the diseases and predators will help keep popula- galls can infest other leaves or migrate down to tions low and reduce the rate of spread. the roots. Most grapes grown in British Colum- bia are not susceptible to leaf galls and the life Cultural Control cycle here largely consists of asexual forms When establishing a new vineyard, purchase confined to the roots of grapes. For this reason, plants from reputable suppliers and ensure that infestations spread at a relatively slow rate. planting material is healthy and free of phylloxe- Feeding by phylloxera on the roots of grape- ra. Vines imported into British Columbia are vines results in severe water and nutrient stress given a hot water treatment to prevent the and eventual death of the vines. Roots become importation of phylloxera and other grapevine stunted and galled and die prematurely from the pests. injection of harmful saliva and invasion of To ensure that phylloxera are not moved from fungal pathogens (4b). Depending on vine infested to clean areas on farm machinery, vigour and the size of the infestation, vines can disinfest all equipment. Less frequent cultiva- slowly become stressed and chlorotic, or they tion is thought to be helpful. can decline rapidly. Resistant rootstocks provide an effective Monitoring and Spray Thresholds means of combating phylloxera. Almost all resistant rootstocks were developed from Vines that fail to thrive and become chlorotic crosses between several species of wild grapes and unproductive should be inspected for the native to eastern and southern North America presence of phylloxera. Galls on leaves are an (V. riparia, V. rupestris, V. berlandieri and others). obvious indication of phylloxera on hybrid Some of the grape rootstocks with good phyl- varieties, but damage confined to roots of loxera resistance that are commonly grown in vinifera wine grapes can be confused with dam- British Columbia include SO4, 5BB, 5C, 420A, age from nematodes or root diseases. Carefully and 161-49C. A more complete listing of expose the roots and search for the typical phylloxera-resistant rootstocks that includes swellings and dying roots. A hand lens or other characteristics can be found in ‘Phylloxe- dissecting microscope will help verify the ra-Resistant Rootstocks for Grapevines’, presence of phylloxera. Northwest Berry and Grape Information 5.3-10 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection

Network, 2007, posted at: ber- during harvest operations. Paper wasps are rygrape.org/phylloxera-resistant-rootstocks-for- less aggressive than yellowjackets or hornets grapevines. and are not as prone to sting. Rootstocks vary in characteristics such as vigour and it is often difficult to select an appropriate Identification rootstock for a particular vineyard. Soil types, Yellowjacket workers are about 1.5 cm in resistance to nematodes, vine spacing and length; the abdomen appears largely yellow several other factors need to be considered in with thin black bands. Hornets are slightly addition to phylloxera resistance. Prior to larger and appear largely black with yellow or planting it is advisable to read appropriate white bands. Paper wasps have thinner bodies publications and consult with vineyard manag- with a more pronounced constriction (stalk) ers or consultants. between the thorax and abdomen. The body Vigorous vines resist phylloxera damage better is dark with some yellow markings, but they than stressed vines. Provision of additional appear reddish-brown due to the colour of the water and nutrients can help delay the rate of wings and distal parts of the legs (5h). In flight decline. Infested vines should not be heavily the legs of paper wasps dangle visibly below cropped and extra care is required to prevent the body. All of these wasps produce paper additional stresses from insects and diseases. nests, but the brood cells of paper wasps are exposed. Some varieties are more vigorous and are better able to resist damage. Phylloxera infestations Life Cycle and Damage are more damaging and spread more rapidly on heavier soils that are prone to cracking, Yellowjackets and paper wasps overwinter as while vines planted in sandy soils can be nearly fertilized females in sheltered locations. These immune to attack. queens seek suitable nest sites in spring and establish a new colony. Nests are initially small, Chemical Control consisting of only a few paper cells, but as workers develop they assist in building up MoventoTM (spirotetramat), a systemic insecti- colony numbers and the size of the nest. De- cide effective against plant-feeding insects pending on the species, nests can be in the with sucking mouthparts, was recently regis- ground, under the eaves of houses, in hollow tered for the control of grape phylloxera and trees, the walls of buildings, or exposed in trees. mealybug. Sprays should be applied in a In fall, in addition to workers, colonies produce minimum spray volume of 500 L/ha as per both males (drones) and queens. When freezing the label instructions. Do not apply Movento weather arrives, all the drones and workers, as to table grapes. well as the undeveloped larvae and pupae are killed. Wasps Wasps prey on other insects, scavenge food and A number of species of yellowjacket wasps feed on nectar and the juices of fruit. It has (Hymenoptera: Vespidae) are pests of grape; the been reported that wasps do not damage fruit most numerous and troublesome being Vespa themselves but take advantage of injury caused pennsylvanica (Saussure). Two uncommon by other insects or birds, diseases such as sour species of paper wasp (Polistes sp.) are native rot, or splitting of fruit. There are contrary to our area. The European paper wasp, P. reports, however, particularly relating to the dominula, was found in British Columbia in European paper wasp, that they are able to 2003 and has since become very common, directly feed on intact fruit (5h). As mentioned particularly around buildings. Yellowjackets, above, wasps are also a major annoyance and hornets and paper wasps are important their stings result in swelling and a painful itch predators of grape pests throughout most of and can trigger severe allergic reactions in some the year, but in fall they often feed in large individuals. numbers on damaged fruit. Wasps are also an annoyance to vineyard workers and to pickers

Best Practices Guide for Grapes for British Columbia Growers 5.3-11 5 Crop Protection

Monitoring and Spray Thresholds Chemical Control There are no established thresholds for wasps Cypermethrin (RipcordTM) is currently regis- and the need to spray is determined by the tered for the control of wasps feeding on wine variety of grape, past history of damage, and grapes but not on table grapes. The pre-harvest tolerance level of individual vineyard managers. interval (PHI) is two days for wine grapes Trapping of wasps is most effective early in the harvested by machine and seven days for fruit season before the colonies have increased in harvested by hand. number. The recent arrival of the European paper wasp has made it necessary to control Spotted Wing Drosophila wasps more frequently. Drosophila suzukii (Matsumura) Biological Control This potentially damaging pest of grapes was first found in Canada infesting blueberries in the Wasp colonies can be attacked by other wasps. Fraser Valley in September 2009 and trapped Eastern and western kingbirds feed on foraging soon after in a cherry orchard near Kelowna. It adults and larvae are subject to certain diseases. is native to Southeast Asia where it feeds on a The onset of winter eliminates established range of soft skinned fruit. Unlike most species colonies and overwintering queens often suc- of fruit fly (vinegar fly) that feed on very ripe, cumb to cold or are eaten by other insects, or damaged, or rotting fruit, the spotted wing even by mice. drosophila (SWD) is able to attack ripening, firm fruit. Cultural Control Elimination of nests early in the season can be Identification an effective management strategy, but they are Adult spotted wing fruit flies are slightly larger often located outside the vineyard or are well (2-3 mm) than other fruit flies and males have a hidden. Aerial nests in trees or under eaves can dark grey to black spot toward the outer margin be removed and placed in a plastic bag at night of each wing (5g). Females lack the wing spots when wasps are inactive. Nests in walls or and have a saw-like ovipositor visible with the natural cavities can be treated by spraying or aid of a good hand lens or microscope. The puffing commercial wasp control products into elongate creamy white legless larvae, up to 3 the entrance holes at night. Sealing of entrances mm long, are difficult to distinguish from other can help prevent future nests. species of fruit fly. Trapping can be used to reduce numbers of foraging wasps in localized areas. Commercial Life Cycle and Damage wasp traps that use an attractant dissolved in water (e.g. Rescue® Yellowjacket trap) have SWD overwinter as adults. Beginning in spring, proven effective, or homemade versions con- several generations develop throughout the year taining a sugary solution can be made from on a range of available fruit (strawberry, black- recycled 1 litre plastic pop bottles. Wasps enter berry, cherry, etc.), including grapes in the late through small holes and eventually fall into the summer and fall. Typical for fruit flies, females liquid solution and drown. Trapping early in the lay large numbers of eggs that hatch rapidly into season when populations are low and queens larvae that mature at a rapid rate. A generation are establishing colonies is generally more can develop in as little as 1 to 2 weeks when effective than attempting to remove large temperatures are warm, resulting in rapid numbers of wasps later in the season. For increases in numbers and significant damage to additional information on social wasps, man- crops. agement strategies, and design of wasp traps, visit the University of California Statewide Larvae of several species of fruit fly develop in Integrated Pest Management Program, 2008, damaged or decaying grapes late in the season, website at: http://www.ipm.ucdavis.edu/PMG/ causing little damage to the crop. Female SWD Pestnotes/pn7450.html. are able to deposit eggs into undamaged, ripen- ing table grapes with the use of their strong

5.3-12 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection serrated ovipositors and it is possible that a section for details) might help control this and small proportion of thin-skinned wine grapes other fruit fly pests. Exposure of fruit early in are damaged in this same manner. Recently the season results in fruit with thicker skins and completed studies suggest that SWD causes heavier wax cuticles which helps control sour little direct economic damage to wine grapes and bunch rots. grown in south central British Columbia. La- boratory studies have shown that larvae were Chemical Control unable to develop in wine grapes until fruit had Emergency registration of RipcordTM (cyperme- reached a maturity level of nearly 20 oBrix. It thrin), Malathion, DelegateTM (spinetoram), and was not collected from intact, healthy fruit and EntrustTM (spinosad) for the control of SWD formed a smaller proportion of all Drosophila has been requested for 2014. Entrust is a prod- species found in damaged or rotting grapes. uct approved by the Organic Materials Review SWD was found, however, infesting apparently Institute (OMRI) for use in organic vineyards. healthy table grapes. The presence of fruit fly Sprays are required near to harvest to control larvae and pupae in fresh table grapes is a major this pest and it is important to consult the label concern. Feeding by larvae directly damages the and observe the pre-harvest interval (PHI). Sour fruit and the holes created during egg-laying and bunch rots that might be spread to some allow the entry of disease-causing microorgan- degree by SWD are best managed through the isms. The relationship of SWD and other combined use of early season removal of basal drosophila to the spread of sour rot and other leaves and judicious use of fungicide sprays. pathogens affecting ripening grapes is not entirely clear. Grape Mealybug Monitoring and Spray Thresholds Pseudococcus maritimus (Ehrhorn)

There are no established thresholds for this pest Grape mealybug was previously not considered and it remains unclear if it poses a serious threat to be major pests of grapevines grown in British to wine grapes produced in British Columbia. Columbia, as numbers were generally quite low Fruit fly traps and baits are available commer- due to the activity of parasites and predators. cially or they can be made from recycled plastic The recent recognition that they and soft scale pop bottles containing mixtures of yeast, sugar are responsible for the sometimes rapid spread and water or apple cider vinegar as bait. Fruit of grapevine leafroll associated virus 3 has can also be carefully inspected for the presence raised its status to that of a major pest. Direct of larvae or pupae and adults reared out from feeding damage is of little concern. Individual infested fruit in order to provide an accurate bunches of table grapes touching infested vines identification. If you think you have this pest, would occasionally become infested and fruit consult the ‘Spotted Wing Drosophila (Fruit can become coated with sticky honeydew, Fly) Pest Alert’ factsheet, BCMA reducing their marketability. Largely due to the (http://www.agf.gov.bc.ca) for additional detrimental effects of broad-spectrum information. insecticides on beneficial insects, damaging populations of mealybug have become more Biological Control common in recent years. Whenever possible, Parasitic wasps have been reared from SWD in apply chemicals against major pests (leafhop- BC and predators of other species of fruit fly pers, cutworm) of grapes only when required are likely to also attack this species. and only to portions of the vineyard where control is warranted. Select pesticides that are Cultural Control least damaging to predators and parasites. Sanitary measures suggested for other fruit Identification crops (i.e. removal of infested and unharvested fruit) are generally not considered to be practical The grape mealybug (Homoptera: Pseudococcidae) for commercially produced wine grapes. Early has a flattened, oval pink body covered in a season removal of basal leaves (see leafhopper mealy white wax coating (3f). It is somewhat segmented in appearance, but the divisions Best Practices Guide for Grapes for British Columbia Growers 5.3-13 5 Crop Protection between head, thorax and abdomen are not Biological Control distinct. Mature wingless females are about 5 mm long. They have long waxy filaments along Parasitism of grape mealybug has not been the edge of the body that are longest at the rear studied in British Columbia. Research in Cali- and become progressively shorter toward the fornia has shown that at least six species of front end. Large numbers of eggs are laid in parasitic wasps attack them - late summer and cottony masses. The smaller, winged males have fall rates of parasitism often exceed 90%. a pair of long, white anal filaments. Yellow to Predaceous midge larvae feed on eggs, while brown crawlers that emerge from the oval, several species of lady beetles and many other orange eggs are not covered in wax. All stages generalist predators feed on nymphs and adults. are mobile. Mealybug and other homopteran insects (scale, whitefly, aphids, etc.) are susceptible to several Life Cycle and Damage diseases, including Entomopthora fungus. Females move in late fall to old wood and lay Cultural Control overwintering eggs in cottony egg masses under loose bark. Crawlers, some of which might have Mealybugs prefer vigorous vines. Ensure ade- hatched in fall and remained dormant through- quate nutrition and moisture to produce an out the winter, move to new shoots in spring. optimum crop, but avoid excessive vigour. Grape mealybugs mature around mid-summer Research in California has shown that fruit on and produce a 2nd generation that matures in cane-pruned varieties is less likely to suffer late autumn. They can occur on all aerial parts damage compared with spur-pruned vines. of the vines but are more common in summer Clusters on cane-pruned vines hang farther on leaves and new growth, usually hidden away from the mealybug overwintering sites on within the canopy. old wood. Earlier varieties are not exposed to honeydew to the same extent as later varieties. Damage is similar to that for soft scale. Plant sap is removed during feeding and large Heavy infestations of mealybugs and other amounts of honeydew foul the fruit (3f) and honeydew-producing pests of grape are usually promote the growth of sooty mold fungus. tended by ants that feed on the sugary excretion Most fruit damage occurs during the develop- and protect the mealybugs from predation. ment of the second brood in late summer. Control of ants can often contribute to a signifi- Mealybugs can infest grape bunches and are cant decline in mealybug numbers. For small known to transmit certain leafroll viruses. backyard plantings with an isolated infestation, painting a sticky material around vine trunks Monitoring and Spray Thresholds and posts and ensuring that ants cannot gain access to the mealybugs often eliminates the To detect when crawlers are active, remove the problem. Trials in California have also shown loose bark in an area near the infestation and that sprays directed against the Argentine ant, encircle the vine with clear tape applied sticky Iridomyrmex humilis, controlled damaging popula- side out, or use double sided adhesive. Replace tions of the obscure mealybug, Pseudococcus the tape every three or four days and check for affinis. Insecticides are not currently registered the yellowish brown crawlers. A good magnify- for the control of ants in BC vineyards. ing glass or dissecting microscope is useful for this purpose. Later in the season inspect vines Chemical Control for the cottony egg masses, leaves coated with shiny, sticky honeydew, and the presence of Malathion, Diazinon, and Safer’s Insecticidal TM attendant ants travelling up and down the vine Soap can be applied against the crawler stage, TM trunks. The need to inspect vineyards for while Movento (spirotetramat) is active mealybugs can be based partly on past infesta- against all stages due to its good systemic TM tions, vigorous growth, and prior use of broad- activity. Movento should not be applied to spectrum insecticides. Grape mealybug prefer table grapes. vigorous vines with thick canopies.

5.3-14 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection Soft Scale and remain firmly attached to the canes even after death. European Fruit Lecanium Scale, Parthenolecanium corni (Bouché) Life Cycle and Damage Cottony Maple Scale, Neopulvinaria innumerabilis EFLS and CMS overwinter as partly grown (Rathvon) scales on new canes (3c). Growth resumes in About a dozen species of scale insects are spring and females reach maximum size around known to attack grapes in various regions of the early summer when they begin to lay eggs. The world, but only two are commonly found on newly hatched scale called crawlers hatch and grapes in British Columbia. The European fruit disperse during July and August to the under- lecanium scale (EFLS) and cottony maple scale sides of leaves where they settle and feed until (CMS) are both soft scales (Homoptera: Coc- early fall, when they migrate to the current cidae) that rarely cause direct economic injury to year’s wood and develop a hardened protective grapes. They are a greater concern in the pro- shell for the winter. duction of table grapes. The large quantities of Both species of soft scale feed on the phloem of honeydew they produce supports the growth of grapes and a large number of other woody sooty mold fungus that can leave fruit unmar- plants, including many fruit trees and ornamen- ketable. Two species of hard scale (Homoptera: tals. Soft sales have become more abundant Diaspididae), the oystershell scale, Lepidosaphes recently. Direct feeding damage from the ulmi L., and San Jose scale, Quadraspidiotus removal of plant fluids is rarely a cause for perniciosus Comstock, can occasionally be found concern, but the additional stress caused to attacking 2 year old wood of weakened vines. weak vines might be sufficient to hasten death. Hard scales do not produce large amounts of Of greater concern, they produce vast amounts honeydew and are currently of little importance of honeydew that fouls the fruit and supports to the British Columbia grape industry. CMS the growth of sooty mold fungus, potentially and EFLS are considered major pests of grape- rendering table grapes unmarketable. vines due to the recent discovery that they are effective vectors of grapevine leafroll virus 3. Monitoring and Spray Thresholds Identification Partly-grown scales can often be observed during pruning, or watch for honeydew on Female EFLS, also known as brown apricot leaves and fruit during spring and early summer. scale, when fully grown have a chestnut brown, Ants feed on the honeydew and will protect the smooth and slightly shiny protective shell that is scale from predators (3d). They can often be around 5 to 8 mm long and slightly longer than seen in large numbers hurriedly running up and wide (3e). Certain races in some regions report- down posts or vine trunks to and from infested edly produce male scales, but most females canes. reproduce without mating. The small nymphs or crawlers that hatch from the small oval, pearly To detect when small crawlers are active, white eggs are yellow to orange in colour. remove the loose bark in an area near the Mature female CMS are similar in size, shape infestation and encircle the vine with clear tape and colour to EFLS, except that a mass of applied sticky side out or use double sided cottony material containing the eggs, up to adhesive. Replace the tape weekly and check for 1,000 per sac, extrudes from the rear end (3d). the orange coloured crawlers. A good magnify- The much smaller winged males produced in ing glass or dissecting microscope is useful for late summer have no mouthparts and live for this purpose. only 1 or 2 days. Males mate with the immature There are no established thresholds for direct females. Mature scales of both species become damage from soft scale infestations. Small to brittle after the eggs are laid in mid-summer and moderate numbers of scale on a healthy vine are can easily be detached from the one to three unlikely to result in direct feeding damage due year old wood with a fingernail. The smaller to the removal of fluids and nutrients; treatment hard scales (1-2 mm), which are much longer of table grapes is required when the honeydew than wide, do not produce any cottony material they excrete fouls the fruit. It is important to Best Practices Guide for Grapes for British Columbia Growers 5.3-15 5 Crop Protection control infestations of soft scale if vines or Thrips neighbouring vines are known to be infect- Western Flower Thrips, Frankliniella occidentalis ed with Grapevine leafroll virus 3. Pergande Grape Thrips, Drepanothrips reuteri Uzel Biological Control Flower Thrips, Frankliniella tritici Fitch Biological control of scale on grapes in British Several species of thrips can be found feeding, Columbia has not been investigated in any at least occasionally, on grapes; the three most detail, but on other crops and in other regions common are the western flower thrips (WFT), of the world they are known to be heavily the grape thrips (GT), and the flower thrips parasitized by several species of wasps and flies. (FT). Thrips are generally minor pests of They are preyed upon by lady beetles and other wine grapes, but are important pests of generalist predators. English sparrows and table grapes due to scarring of several species of warblers that feed on fully fruit. Their populations often grown soft scale have been known to curtail increase following applications of infestations in some regions. broad-spectrum insecticides that reduce numbers of beneficial insects. Cultural Control All species feed in a similar manner, Healthy vines of moderate vigour are less but differences in biology and timing susceptible to scale infestations and are better of infestations results in differential damage to grapes. able to withstand damage. Routine pruning removes many scales and a small infestation can Identification be pruned out in spring or early summer. All species have long, slender bodies with dark Chemical Control protruding eyes and relatively short beaded antennae. Adults have two pairs of wings that Oil or lime sulphur applied as high volume are heavily fringed along the edges. WFT are dormant sprays to the trunks and cordons of dark yellow to brown and 1 to 1.5 mm long (5a). vines for the control of powdery mildew will GT and FT are both around 1 mm long, the help suppress soft sale and other small, soft former is amber yellow with a yellowy-orange TM bodied pests of grapevines. Movento (spiro- thorax, and the latter is uniformly pale yellow to tetramat) is registered for the control of scale on nearly white. Nymphs of all species are similar wine grapes during the growing season, but it in appearance to the adults except that they are should not be applied to table grapes. Malathion smaller, slightly paler in colour and lack wings. can be used against the crawler stage and insec- Thrips tend to be very active; adults not only fly ticidal soap will provide some suppression of but also run and hop rapidly. this active stage in summer. Repeat applications might be required as long as crawlers are active. Plant feeding thrips should not be confused with predaceous thrips. Adults of beneficial thrips may be dark black or purplish black with clear wings or wings that appear light grey with Secondary and Minor white bands, or they are pale with dark bands Pests on the wings. They are slightly larger to nearly twice as large as the pest species. Nymphs of A number of insect and mite pests of grapes predaceous thrips have bodies that are banded occur only infrequently or cause significant yellow and orange, are reddish purple in colour, amounts of damage only after chemical treat- or are pale with the joints of the appendages ments have reduced numbers of predators and dark. Compared with phytophagous species, parasites that normally regulate their numbers. predaceous thrips have front legs that are The best way to manage these pests, then, is to enlarged and slightly curved that they use for properly manage populations of primary pests grasping prey. These features and the slightly so as to preserve and enhance numbers of larger mouthparts are best observed under a beneficial insects and mites. dissecting microscope.

5.3-16 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection Life Cycle and Damage WFT and FT in spring from around 75% bloom to the end of fruit set and apply insecticides as Adult female thrips overwinter under leaves and required. Verify the presence of thrips by plant debris on the ground. In spring they sharply striking fruit clusters or leaves against a deposit their eggs into developing leaf, stem, dull white or green coloured surface. The and flower tissues. The time from egg to adult is decision to spray should be based partly on the about three weeks during warm weather, and table grape variety, records of past damage, and several generations are produced yearly. Most the intended market for the fruit. There are no thrips feed on a wide range of host plants and firm thresholds for thrips infesting grapes in large numbers will often move to a succession British Columbia of new succulent hosts throughout the year. Both adults and nymphs feed by rasping the leaf Watch for GT damage to young leaves and surface and sucking up the escaping fluids. shoots during summer and early fall. Use an eyepiece or magnifying glass to verify that thrips WFT adults enter vineyards in early spring, are present. As for fruit clusters, leaves and often in large numbers, when saskatoon bushes shoots can be held over a piece of white card- have finished flowering and other native vegeta- board and sharply hit to dislodge the thrips. tion is beginning to dry down. In addition to Control on mature vines is usually only warrant- ground cover plants, WFT feed on flower and ed when growth is stunted sufficiently early in fruit tissues of grapes from bloom to just after the summer to delay ripening and affect growth fruit set. Their feeding under caps and persistent the following season. flower parts causes berry scarring and russeting (5b). White and green grape varieties are also Biological Control damaged when females insert their eggs into fruit, causing dark spots or halo spots. Feeding Predatory bugs such as the minute pirate bug on developing shoots is occasionally so heavy (Orius tristicolor), anthocorids (Anthocorus melanoce- that shoots are stunted and leaves deformed rus), and deraeocoris (Deraeocoris brevis) are all (5b), but damage of this sort often only occurs known to feed on thrips. Studies in the Okana- around the perimeter of vineyards. WFT usually gan and Similkameen valleys have indicated that decline greatly in numbers following fruit set. predatory thrips are important regulators of pest FT have a similar biology and contribute to the thrips populations. In the laboratory, predatory damage caused to fruit in spring, but they are thrips at a density of one every 10 to 15 leaves is not as numerous as WFT. sufficient to control WFT.

GT are generally only found in significant Cultural Control numbers on grape during the summer months, and their feeding is largely confined to leaves So that thrips are not forced to feed on table and shoots. Numbers can build up rapidly, grapes when they are most susceptible to fruit however, particularly following insecticide damage, avoid mowing cover crops during treatments for other grape pests. Leaf veins can bloom and fruit set. be scarred and fail to expand properly, leaf edges can become necrotic, and shoot growth Chemical Control inhibited, resulting in shortened internodes. Spinosad (SuccessTM or EntrustTM) is registered for suppression of thrips on grapes. Insecticidal Monitoring and Spray Thresholds soap applied for mites and grape mealybug will WFT often invade vineyards in large numbers also help suppress thrips populations. for only brief periods in spring and it and the FT are not normally an economic concern for Spider Mites wine grapes. Scarring of fruit has not been European Red Mite, Panonychus ulmi (Koch) shown to affect wine quality and damage to Two-spotted Spider Mite, Tetranychus urticae leaves and shoots is usually minor. Damage Koch usually occurs over a short period of time, which makes early detection and control diffi- The main species of spider mites infesting cult. Inspect table grapes for the presence of grapes in British Columbia are the European red Best Practices Guide for Grapes for British Columbia Growers 5.3-17 5 Crop Protection mite (ERM) and the two-spotted spider mite Life Cycle and Damage (TSSM). They differ somewhat in biology, but feeding damage and management strategies are ERM, our most common species, pass the largely the same. Spider mites should be winter as eggs laid on vine canes and trunks. considered secondary or induced pests of Eggs hatch in spring and the young microscopic grapes; their numbers increase following the nymphs begin to feed on young foliage. TSSM use of broad-spectrum insecticides that overwinter as fertilized females under the bark reduce numbers of spider mite predators. or in other sheltered areas around the base of Although it is somewhat selective in action and vines. When warmer weather arrives in spring preserves populations of some predators, the the females begin to feed and deposit eggs. Both insecticide AssailTM is toxic to predacious thrips species can produce around six to eight over- that are effective predators of mites in British lapping generations each season and all stages Columbia vineyards. Studies in Washington can be found on grapes at any time during the State have also shown that the active ingredient summer months. Females of both species are in AssailTM and related materials increases spider capable of producing 200 or more eggs each mite reproduction. Due to its persistence, and development can be rapid during warm increases in mite numbers can occur up to weather. Spider mite populations can, there- several months after application. Mite outbreaks fore, explode rapidly under favourable can also occur following applications of pyre- conditions. throid insecticides (e.g. permethrin) and other Both adults and nymphs feed by piercing broad-spectrum insecticides. individual leaf cells and removing the fluid contents. Healthy grapevines can tolerate Identification moderate numbers of spider mites, which will cause chlorotic spots on the leaves. Heavy Adults of both species are small, around 0.5 mm feeding results in brown leaves that fall prema- in length, and best viewed with the aid of a turely; reducing photosynthetic activity and vine magnifying lens. They are nearly spherical in vigour. Heavy feeding damage can delay ripen- shape and have eight legs and short piercing ing of fruit. The large amount of webbing mouthparts. The ERM is dark red in colour produced particularly by the TSSM can also be a with long pale hairs (setae) projecting from cosmetic problem for table grapes. small pale circular areas on the dorsal surface (4h). The oval eggs are bright orange with a distinctive hairlike projection on the upper side. Monitoring and Spray Thresholds The TSSM varies in colour from pale yellow to Spider mites rarely cause significant damage to greenish yellow to bright orange; the common grapes prior to mid-summer. No firm thresh- olds have been developed for spider mites on grapes in British Columbia, but approximate guidelines can be suggested from research conducted in other countries. In Europe, a threshold for ERM on grapes was determined to be 60 to 70% infested leaves in spring, while in summer leaves with 1 or more mites should not exceed 30 to 45% of total leaves on a shoot. Because a similar threshold has been suggested for TSSM in Switzerland, numbers of both species can be combined into a single spider mite count. A good hand lens or low-power pale form has a distinct dark dorsal spot on each dissecting microscope would help provide side of the body (4g). Its eggs are white. Both accurate counts of infestation levels. A fairly species feed on the undersides of leaves. TSSM reliable method is to monitor damage to leaves usually congregate in clusters and produces large and spray when a moderate amount of ‘bronz- quantities of silk webbing, while ERM produce ing’ has occurred, around 10% defoliation. less webbing and are more evenly distributed Because mite numbers can increase very rapidly over the leaf surface. 5.3-18 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection it is necessary to monitor grapes frequently effective predators that feed almost exclusively during hot weather. on mites. Stethorus picipes is a small, dark species of ladybeetle with a slightly hairy appearance. When monitoring for mite damage it is useful to The elongate bodies of the larvae are also nearly consider previous infestation levels. Vineyards black in colour with a body covered with nu- with low chemical inputs that have not experi- merous hairs. At least four species of predatory enced severe spider mite outbreaks in the past thrips can be found in Okanagan Valley vine- are unlikely to require treatment, while those yards; adults of three of these are black, while that have been treated with broad-spectrum the fourth, the six-spotted thrips, Scolothrips insecticides should be observed more closely. sexmaculatus, is pale with dark spots on the Biological Control wings. All four species feed on spider mites, and healthy numbers of these predators are usually Spider mites were of minor importance prior to associated with low populations of their prey. the widespread use of synthetic pesticides. Due The western flower thrips is considered a pest largely to the harmful effects of pesticides on of grapes, but it is also known to feed on the populations of predators, spider mites are now eggs of spider mites. the most important pests of grapes in many regions of the world. The first course of Cultural Control action for the management of spider mites Vineyards can be managed in ways that help is the preservation and enhancement of alleviate mite problems. Hot, dry and dusty beneficial species. Pesticides should only be conditions favour the buildup of spider mite applied when necessary and only to parts of the populations. Where mites are a problem, road- vineyard where pest populations are sufficiently ways can be treated with oils or other materials high to warrant control. Whenever possible to reduce dust. Vineyards that are continuously select materials that are least damaging to non- cultivated will produce more dust than those target species. Numbers of spiders and benefi- with permanent ground covers. Moreover, a cial insects are usually higher in vineyards with permanent mixed groundcover will support permanent, mixed groundcover that provides greater numbers of beneficial insects and pollen and alternate sources of prey. Proximity predaceous mites. Compared with bare soil, to uncultivated or unsprayed areas allows planted drive rows will decrease air tempera- beneficial insects to re-colonize vineyards tures and raise humidity levels somewhat, following spray treatments. providing less favourable conditions for spider Several species of predatory mites (e.g. Metasei- mites. Spider mite populations can become ulus, Typhlodromus and Amblyseius species) feed on elevated on vines suffering severe drought spider mites and their eggs. Most beneficial stress, and these plants are also less able to mites are a pale opaque colour but they can tolerate damage. Overhead irrigation will help appear light orange if they have been feeding on reduce mite infestations. ERM. They are oblong in shape and slightly smaller than adult spider mites. The long-legged Chemical Control orange whirligig mite (Anystis agilis) is uncom- TM mon on grapes in British Columbia. Like most A number of miticides (e.g. Acramite , TM TM TM other predatory mites, this large species is more Kelthane , Envidor and Pyramite ) are active than its prey. Predatory mites are very registered on grapes for mite control. Safer’s TM sensitive to a range of pesticides, including Insecticidal Soap or PureSpray Green Spray TM sulphur fungicides at high rates and pyrethroids Oil provide a more benign approach to mite such as permethrin (PounceTM). control but offer only moderate suppression of spider mites. Materials with different modes of A number of spiders and predatory insects feed action (chemical groups) should be used in on spider mites or their eggs. Many species, rotation to help prevent the development of such as the minute pirate bug (Orius tristicolor), resistance. are generalist predators that do not specialize on mites, while others such as the aptly named spider mite destroyer, Stethorus picipes, are very Best Practices Guide for Grapes for British Columbia Growers 5.3-19 5 Crop Protection

Grape Erineum Mite suffering from other stresses. Establishment of newly planted vines can be delayed somewhat = Grape Leaf Blister Mite, Colomerus vitis by erineum mite feeding, which will retard or (Pagenstecher) reduce fruiting. Identification Monitoring and Spray Thresholds Adult erineum mites are only 0.2 mm long and a Erineum galls are usually very apparent during dissecting microscope is required to observe routine vineyard operations. Grape varieties them properly. Their creamy pale bodies are differ in susceptibility to this pest and it is elongate with only two pairs of legs. Although important to check individual blocks for the erineum galls can be confused with certain presence of mites. In order to prevent prema- fungal diseases or phylloxera leaf galls by inex- ture loss of leaves, new vines should be perienced growers, their characteristic inspected and treatments applied if large num- appearance is the best way to identify these bers of galls are found on most leaves during pests. The hemispherical concave galls or erinea the spring or summer months. formed on the undersides of leaves initially have a felty white appearance due to the presence of densely packed long leaf hairs (4d). Opposite to Biological Control these galls, bumps will be visible on the upper The western predatory mite, Galendromus surfaces of leaves. These swellings are a reddish occidentalis, is an important erineum mite preda- colour in spring and turn green as the leaves tor. Predaceous thrips will feed on exposed mature. Small numbers of mites feed on the mites, but their effectiveness is likely limited dense hairs in each gall, which eventually turn when mites are protected within the dense brown. Two other forms of erineum mite, the hairs of the galls. leaf-curling strain and bud-inhibiting strain, have been reported recently from Washington Cultural Control State and are possible in British Columbia. The New plants may become infested in the nursery. former causes slight to severe downward curling Ensure that material used to establish new of leaves in summer with stunting of shoots and vineyards is free of mites and other pests or increased growth of lateral shoots. Feeding of diseases. Removing galled leaves can control the bud-inhibiting strain on buds causes a range light infestations to some extent. Research of abnormalities, including scarified shoots, conducted in the Okanagan Valley demonstrat- short zigzagging internodes, dead terminal buds ed that removal of infested leaves in May did and malformed leaves. For additional infor- not alter yields or fruit quality. mation on erineum mites and other pests of grapes, visit the University of California Inte- grated Viticulture Online website (Viticultural Chemical Control Information > Insects and Mites). Erineum mite is seldom a problem in vineyards where sulphur is applied routinely for powdery Life Cycle and Damage mildew control. Applications of sulphur (e.g. KumulusTM DF, or wettable sulphur) are Adult erineum mites overwinter under the scales most effective early in the season when galls of buds. Mites move in spring to developing are first being formed on new leaves. Sulphur shoots and create galls on young leaves around sprays should not be used on Foch or Vitis the fruiting zone. Several generations are pro- labrusca varieties as they are susceptible to leaf duced each year with new galls developing and fruit damage. Miticides (acaricides) such as higher up the shoots. Beginning in late summer, PyramiteTM or KelthaneTM applied against spider adult mites move back to the buds for winter. mites and sprays of organophosphates (e.g. Leaves with a few to many erineum galls appear malathion and SevinTM) for control of leafhop- to function normally and there is little or no pers will also reduce numbers of erineum mite economic damage to mature vines until almost somewhat. all leaves are covered with galls. Even then, damage usually only occurs if vines are also 5.3-20 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection Grape Leaf Rust Mite tion that rust mites need to be controlled the following spring. Calepitrimerus vitis (Nalepa)

Monitoring and Spray Thresholds Grape leaf rust mite, which belongs to the same family (Eriophyidae) as grape erineum mite, was There are no established thresholds for this identified for the first time on grapes in the pest. Control is indicated when a significant Okanagan Valley in 2009. Growers are referred proportion of leaves become bronzed in late to the following source for additional infor- summer. mation: Grapevine pests and their management, by A. Loch. Primefact 511, New South Wales Biological Control Dept. of Primary Industries, NSW Australia posted at: www.dpi.nsw.gov.au/primefacts. As for erineum mite, western predatory mite, Galendromus occidentalis, other mite predators, and Identification predacious thrips are often able to keep rust mites in check. To maintain healthy popula- A microscope is required to properly identify tions of beneficial insects and predatory mites, it these 0.2 mm long pale white wormlike mites is important whenever possible to limit the use that closely resemble erineum or blister mites, of insecticides and to apply selective materials but do not form leaf galls. They are much that are less toxic to predatory mites. smaller than spider mites and elongate rather than round, tapering at the rear, and having two Chemical Control pair of legs near the head (4e). Their presence is best determined by the bronzing of leaves A successful rust mite control program devel- during July and August that results from their oped in Australia relies largely on spring feeding. Unlike spider mites that cause similar applications of sulphur (e.g. KumulusTM DF, damage to leaves, grape leaf rust mites do not or wettable sulphur) in high volume sprays produce webbing. during bud swell to woolly bud stage. Sulphur sprays should not be used on Foch or Life cycle and damage Vitis labrusca varieties, as they are susceptible to leaf and fruit damage. There are no miticides Adult rust mites that spend the winter under currently registered for the control of grape leaf bark or bud scales move in spring to the devel- rust mite. oping buds to feed and lay eggs. Large numbers of adults concentrated on the available green tissue in early spring can damage buds, resulting Snailcase Bagworm in deformed leaves, scarring of shoots, reduced Apterona helix Siebold shoot growth, reduction or loss of fruit clusters, and even death of buds (4f). Early season rust Identification mite damage can be confused with cold injury This introduced moth or damage from other causes. Damage becomes (Family Psychidae) remains less visible as the season progresses and shoots throughout most of its life lengthen. Immature mites that hatch over a within a snail-like case period of several weeks feed under the bud made from particles of soil scales, eventually moving to feed on developing and sand bound together leaves. Unlike spider mites, rust mites infest with silken threads. When equally the upper and lower leaf surfaces. Many fully grown the coiled case is approximately 4 generations are produced throughout the mm in diameter (4f). There are no males and the summer. Before leaves drop in the fall, adult wingless female moths remain inside the case to rust mites migrate to the cordon and trunk for deposit their eggs without having mated (par- the winter. Bronzing of leaves is most obvious thenogenetic reproduction). Large aggregations during July and August, but damage to leaves is often form on posts, tree trunks, or vine trunks not thought to cause serious damage to the in late summer. vines. Extensive bronzing of leaves is an indica- Best Practices Guide for Grapes for British Columbia Growers 5.3-21 5 Crop Protection

Life Cycle and Damage Chemical Control Young caterpillars overwinter within the case DipelTM (Bacillus thuringiensis) is registered for formed by the mother. They drop to the ground snailcase bagworm control on grapes and sprays in spring, form C-shaped cases, and begin to applied for the control of other insects will feed on a wide range of weeds, native plants and provide some protection. For this reason, they cultivated crops. Damage consists of small are more common in organic vineyards or excavated holes on the leaf surface. As the larva conventional vineyards with low chemical grows it eventually expands its case into the inputs. typical snail-like, helical shape. In mid-summer the fully grown larvae will climb vines, posts or European Earwig buildings, attach themselves firmly with silk, and (Forficula auricularia L.) pupate within the case. Several weeks later the females emerge, lay eggs, and then exit the case The European earwig is both a beneficial to die. The eggs hatch in late summer and the insect and a pest of table grapes. All stages small first instar larvae spend the winter within feed on small, soft-bodied insects such as small the protective cases. There is only one genera- leafhopper nymphs and will scrape leafhopper tion per year. eggs off of leaves. In fall they feed to some extent on damaged grapes and their presence in Monitoring and Spray Thresholds table grapes is not appreciated by some con- sumers. On grapes produced for wine they Larvae of the snailcase bagworm cause minimal should be considered important generalist feeding damage to leaves and they are not predators. considered economic pests of wine grapes. The large aggregations are easily detected on build- Identification ings, posts, wires, and the trunks of vines. If contamination of table grapes is a concern, Adult earwigs (Order Dermap- inspect vines and apply control measures before tera) are dark brown, about 1.5 the overwintering aggregations form in late cm long, with a pair of forcep- summer. The non-feeding overwintering stage, like appendages (cerci) at the secure within the case, is not susceptible to rear of their elongate bodies. insecticides. The anal forceps of females are long and straight, while those Biological Control of males are curved. Earwigs seldom fly and the membranous hind wings usually remain folded Because it has not yet been adequately studied, up under the short leathery forewings, exposing natural enemies of this pest of grapes in British the abdomen. The four nymphal stages resem- Columbia are unknown. The protective case ble the adults except that they are smaller and would provide some protection from certain wingless. Earwigs are largely nocturnal and hide generalist predators, but predators, parasites and during the day, often in large aggregations, in diseases undoubtedly take their toll. cracks and crevices, or under bark. When disturbed they move quickly. Cultural Control Snailcase bagworm prefer moist areas with thick Life Cycle and Damage vegetation. Avoid excessive irrigation and drain Adults overwinter in the ground in earthen cells. areas that puddle or remain damp. Bagworm are Clutches of eggs laid in cells in the top 5 cm of uncommon in vineyards planted on light soils soil in the fall and spring are opened by females with drip irrigation. Proper drainage will also in spring to release the young nymphs. Adults help reduce grapevine root diseases. Occasional are semi-social and tend their young for a period discing or mowing of areas of the vineyard of time after birth; nymphs later disperse to where bagworm are a problem can help reduce secure locations under rocks, in crevices, or infestations. under bark. Adults develop by mid-summer and there is only a single generation per year. Ear- wigs are nocturnal and feed at night on dam- 5.3-22 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection aged fruit, tender plant tissue, small soft bodied They are active only at night and remain insects, and other foodstuffs. They rarely hidden under plant debris or loose bark damage grape leaves. during the day, making detection difficult. Raucus root weevil adults, in contrast, can Monitoring and Spray Thresholds often be found feeding on the buds of grapes at twilight or on overcast days. Rolled up newspaper or cardboard, or flat Earlier emergence of adult raucus root boards placed on the ground, can be used to weevil in spring that coincides with the monitor earwigs. It might be possible to use development of grape buds accounts for the these same refuges to enhance their numbers in greater damage by this species as compared wine grapes. with the black vine weevil. Although local- ized and usually confined to the edges of Biological Control vineyards, infestations of raucus root weevil Birds, large spiders, wasps and ground beetles have occurred occasionally in large numbers prey on earwigs. Earwigs, in turn, feed on the that required control. The raucus root eggs and small nymphs of leafhoppers and weevil was reported from the Okanagan on other soft bodied insects. Valley for the first time in 1979 and there have been three localized outbreaks docu- Cultural Control mented since that time.

Tillage in spring and fall will destroy some of Identification the earthen cells. For table grapes, mowing, tillage, removal of loose bark from vine trunks, The flightless adults of both species have and sanitation will remove hiding places and long, broad ‘snouts’ typical of weevils help reduce earwig numbers. They can be kept (Coleoptera: Curculionidae). The thick, out of small plantings of table grapes by apply- roughened front wings are fused together. ing sticky tape or commercial Stickum® around Adults range in size from 5.5-7.5 mm for trunks and posts. Washing table grapes after the raucus root weevil and 7.5-10 mm for harvest will help dislodge many earwigs. They the black vine weevil. In addition to their are less likely to seek refuge in table grape slightly smaller size, raucus root weevil can varieties with loose, open fruit bunches. be differentiated from black vine weevil by their generally lighter, patchy appearance Chemical Control and often a distinct difference in colour between the head/thorax and the elytra that Earwigs are sensitive to most insecticides cover the abdomen (1f). and sprays applied for the control of other grape pests will usually also provide control Black vine weevil adults are a uniform black of earwigs. Commercial earwig baits are also colour. Unlike adult raucus root weevil that available. damage buds, leaves with deeply notched edges not associated with damage from Root Weevils other chewing pests are an indicator of black vine weevil feeding. Traps for both Black Vine Weevil, Otiorhynchus sulcatus F. species can be made from cardboard loosely Raucus root weevil, O. raucus F. wrapped around vine trunks where the weevils will hide during the day. Adults can Life Cycle and Damage also be collected on beating trays placed Black vine weevil and raucus root weevil beneath canes and cordons that are hit spend the winter in the soil as pale, legless sharply with a stick or bat. Care needs to be larvae feeding on the roots of a wide range taken, however, as adults often fall to the of plants. It is not known if they feed on the ground as they are approached. roots of grapevines to any extent. Adult black vine weevils feed during late Click Beetle spring and summer on grape clusters and Coleoptera: Elateridae leaves and sometimes girdle fruit clusters. Click beetles were formerly considered to be Best Practices Guide for Grapes for British Columbia Growers 5.3-23 5 Crop Protection important pests of grapes in British Columbia, development to the adult stage. but extensive study in Okanagan vineyards over Larvae are not known to damage the roots of a number of years has shown that most of the grapes to any extent, preferring to feed on the damage formerly attributed to click beetle adults roots of weeds or grasses. As for cutworm was in fact caused by half grown cutworm larvae, feeding of adults on buds of grape causes larvae. Several species will feed occasionally on the buds to die. Yields can be reduced and buds of grapes, but control is usually not war- ripening of fruit can be uneven and delayed. ranted. Click beetles are also not considered Little damage occurs after bud break. pests of grape in Washington State. Monitoring and Spray Thresholds Identification Adult click beetles feed on buds so infrequently Click beetle larvae, called wireworms, have long, that monitoring for these pests is generally not slender, hard bodies that are a light tan to a light warranted. The presence of adult click bee- orange-brown in colour and appear somewhat tles in a vineyard does not indicate feeding shiny and polished. Their short legs and cylin- or correlate with damage. There are no drical slender bodies allow them to burrow established thresholds in British Columbia through the soil to feed on the roots of plants. relating click beetle numbers to bud damage. To Adult beetles have determine if bud damage is due to click beetles elongate somewhat or cutworm larvae, it is best to inspect vines flattened bodies with the aid of a flashlight soon after dark on usually in shades of warm spring nights. brown or black (1e). The segment behind Biological Control the head has small Little information is available on the biological projections that point control of click beetles in British Columbia backward on each side vineyards. of the body. Adults of most species are Cultural Control around 1 to 1.5 cm in length but some are As for climbing cutworm, the presence of significantly larger. broadleaf weeds in spring helps reduce damage When adults are placed upside down in the to grapes. palm of a hand or gently held between finger and thumb they will rapidly flex their bodies at Chemical Control both ends and attempt to right themselves or Chemical control of click beetles is generally not escape with a characteristic clicking action. warranted and none are registered specifically for adults on bearing vines. Sprays for cutworm Life Cycle and Damage larvae should help control adult click beetle. Adults that have spent the winter under debris and leaves emerge with the arrival of warm weather in spring to feed on the tender buds and leaves of a wide range of plants, including Miscellaneous Insect occasionally grapes. They are often quite com- mon on flowers where they feed on soft tissues Pests and pollen. After feeding for a short time, females begin to deposit eggs into the soil. In In addition to the major and minor grape pests two or three weeks the eggs hatch into small described in previous sections, a number of slender ‘worms’, the larvae, that develop in the insects attack grapes only very rarely and are soil throughout the summer. Click beetles can generally not of economic importance in British persist for a long time without feeding and they Columbia. Following are brief descriptions of a often require more than one year to complete few of these occasional pests.

5.3-24 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection Wood-Boring Beetles appears segmented. There are several genera- tions per year. Whitefly feed by sucking juices Two or three species of wood-boring beetles from the leaves, much as scale insects do, and can occasionally infest older canes and vine they also produce large amounts of sugary trunks. Depending on the species, adults are honeydew. Populations are controlled by para- brown to black, cylindrical in shape, and from sitic Encarsia wasps that turn the scales black, by 5-10 mm in length. They have hardened fore- several predatory insects, and by pathogenic wings typical of beetles and indistinct body fungi. sections. Adults burrow into the spurs and canes at the base of new shoots, causing them Western Grape Rootworm to wilt or break. The pale larvae or grubs bur- Bromius obscurus (L.) row through living or dead tissues. Damage usually occurs on older or diseased vines. The western grape rootworm is a widespread pest of grapevines in Europe and California, but Grasshoppers damage to grapes in British Columbia was not Orthoptera: Acrididae reported until recently when an outbreak oc- curred in the Kelowna area. Fully grown larvae Adults and nymphs of several species of grass- are C-shaped white grubs about 7 mm long with hopper feed on grape leaves, usually beginning yellowish brown heads and dark mouthparts. in late summer when preferred hosts begin to Adult beetles are about 4 mm long and some- dry up. Feeding by these well-known, long- what hairy with nearly black heads and dark legged jumping insects consists of chewing bodies (5d insert). Adults, which are all females, damage to leaf margins, most often on lower start emerging in May and feed on the expand- leaves. Grasshoppers suffer from pathogenic ing leaves of grapes, causing long slit-like holes diseases when populations are high. Preying (5d). Larvae initially feed on root hairs before mantids, toads, and many species of birds feed tunneling into the roots of grapevines. Feeding on adults, while smaller nymphs are attacked by by western grape rootworm larvae is known to spiders and a number of predatory insects such cause the death of vines in California due to as ground beetles. direct damage to the roots and entry of second- ary pathogens. Additional information is Whitefly available at http://www.al.gov.bc.ca/cropprot/ Homoptera: Aleyrodidae bromius_obscurus.pdf. Several species of whitefly occasionally infest grapes. Overwintering whitefly are relatively rare Minor Cicada in British Columbia. Some sub-tropical and Platypedia minor Uhler tropical species, such as the common green- Adult minor cicada (Homoptea: Cicadidae) are house whitefly, Trialeurodes vaporariorum about 2 cm long with two pairs of large, trans- (Westwood), infest outdoor plants each season parent wings held roof-like over the body (3b). from infested greenhouses, house plants, and The pale, wingless nymphs have enlarged front vegetable and ornamental transplants. Adults legs that they use to dig through soil. Cicadas are small, around 2 mm in length, with two pairs are mostly known from the loud buzzing or of wings that are covered with a fine, white clicking noises that males produce on hot powder (3h). They somewhat resemble small summer days. They are difficult to locate and white moths. The minute crawlers are mobile will move around to the opposite side of trees for only a few hours until they settle and devel- or posts when approached. Damage to individ- op into nearly translucent, scale-like immobile ual shoots occurs occasionally when females nymphs. The ‘scales’ have a fringe of waxy deposit eggs into canes with their long, saw- material projecting from the bottom edge (3g); toothed ovipositor. Deposition of several eggs the distribution and numbers of the projections into a cane can weaken it or cause it to break. can assist in species identification. The pupal The oviposition damage is recognizable by the stage that develops inside the case on the slivers of wood protruding from a series of underside of leaves is somewhat bulbous and punctures. Newly hatched nymphs drop to the Best Practices Guide for Grapes for British Columbia Growers 5.3-25 5 Crop Protection ground to spend two to three years feeding on ically important pests of grapevines will arrive in the roots of plants. It is not known if they feed our region from elsewhere. Growers can help on the roots of grapes. prevent the establishment of new alien pests by knowing the species currently found in British Three-Cornered Alfalfa Columbia and reporting new pests and unfamil- iar damage. The list of potential grape pests Treehopper that might arrive in British Columbia from Spissistilus festinus (Say) elsewhere is very long. Following is a list of a Adult three-cornered alfalfa treehopper (Homop- few economically important ones and sources tera: Membracidae) are green in colour and about for additional information. 6 mm in length. The pronotum is elongated to the sides and extends to the rear of the abdo- Brown Marmorated Stink men so that they look somewhat triangular Bug when viewed from the front. Lacking the large Halyomorpha halys Stål side projections, the buffalo treehopper, S. bisonia Kopp & Yonke, which also reportedly The brown marmorated stink bug (Hemiptera: feeds on grapevines, has the hump-backed Pentatomidae) was first found in eastern North appearance of the American Bison after which it America in 2001 and more recently in Washing- is named. Mainly restricted to the south end of ton and Oregon. It feeds on a wide range of the Okanagan Valley, damage caused by the vegetables, field crops, ornamental trees and three-cornered alfalfa treehopper can somewhat shrubs, and fruit crops including grapes. Similar resemble leafroll virus. In summer late instar in size and shape to some of our native stink nymphs will produce a series of feeding punc- bugs, first instar nymphs are bright red marked tures around leaf petioles or stems (3a), resulting with black, while adults are dark brown with in decreased flow of water and nutrients and white banding on the antennae and legs. Adults eventual reddening of leaves beyond the feeding are a little more than 1.5 cm in length. In areas site. The initial feeding punctures coalesce into a where they have become established they are darkened band of sunken tissue encircling the often found feeding in close proximity to one stem or leaf petiole. Although damage is often another. Adults aggregate in large numbers in restricted to lateral shoots and generally not of the fall to spend the winter in protected areas or economic concern, growth of newly planted invade houses. Damage results from feeding vines could be stunted in areas with lots of punctures and removal of fluids from the plant, alfalfa or other suitable host plants. resulting in shrunken, distorted buds, shoots and fruit. For additional information on this pest see the Prevention of New Grape brochure ‘Brown Marmorated Stinkbug’, Pests BCMAL, posted at http://www.agf.gov.bc.ca/ cropprot/bmsb_alert.pdf Provincial Entomologists (currently Susanna Acheampong, Kelowna; Tracy Hueppelsheuser, Light Brown Apple Moth Abbotsford), AAFC researchers, and Canadian Epiphyas postvittana (Walker) Food Inspection Agency (CFIA) regulators and inspectors contribute to the prevention of the The light brown apple moth, which is native to arrival of new invasive pests of grapevines into the cooler, wetter coastal regions of Australia, British Columbia. Importation of host plant was found in parts of California in 2007. As for material from areas known to harbour these other members of this moth family (Tortri- pests is regulated and plants inspected upon cidae), it has a wide host range that includes arrival or at the source nursery. Information is ornamentals, fruit trees, berries, and grapes. provided to industry members and the general There likely would be two generations under public through talks, identification factsheets our conditions. Larvae that grow to about 1 to and brochures. It is inevitable that new econom- 1.8 cm in length are pale to medium green with 5.3-26 Best Practices Guide for Grapes for British Columbia Growers 5 Crop Protection a tan coloured head. Adult moths are medium become contaminated with frass and webbing tan often with oblique markings of darker tan to and are subject to fungal infections. brown. Partly grown overwintering larvae feed Visit http://www.ipm.ucdavis.edu/EXOTIC/ on grape buds in spring and continue to feed on eurograpevinemoth.html for information on the developing shoots, tender leaves and flower European grape vine moth, and clusters as they mature. Damage to fruit later in http://www.nysipm.cornell.edu/factsheets/gra the season reduces the crop and allows the entry pes/pests/gbm/gbm.asp for the American of disease organisms. grape berry moth. For additional information on the light brown apple moth visit UC IPM Online,

‘http://www.ipm.ucdavis.edu/PMG/r23023030 11’. Additional information on European and American grapevine pests and their Grape Berry Moths control: Bettiga, L.J. 2013. Grape pest Management, 3rd The European grape berry or vine moth, Lobesia Edition. University of California, Agriculture botrana (Denis & Schiffermüller), and the Amer- and Natural Resources, Pub. No. 3343. ISBN- ican grape berry moth, Paralobesia (=Endopiza) 13: 978-1-60107-800-1. viteana Clemens, are similar in appearance and biology and cause similar damage to grapes. The UC Integrated Viticulture Online. University of former was first reported in Napa County, California website. Main Menu>Viticultural California, in 2009, while the latter from eastern Information>Insects and Mites. North America is now found in parts of western UC IPM Online. University of California Colorado. The slender larvae reach a maximum website (www.ipm.ucdavis.edu). Main size of 1 to 1.5 cm and are green to light pur- menu>agriculture>grape>insects and mites. plish with a darker contrasting head and first thoracic segment. The adult moths are generally 2014 Pest Management Guide for Grapes in less than ¾ of a centimeter long and of a Washington. WSU Extension Publications. medium brown colour mottled in patches of Revised 2013. (Free downloadable PDF version lighter or darker brown, black grey or blue at: cru.cahe.wsu.edu/CEPublications/eb0762/ depending on the species. Both are best identi- eb0762.pdf). fied by the damage caused by larvae feeding on flowers and fruit. Larvae of the 1st generation 2014 Pest Management Guide for Wine Grapes feed on developing buds, flowers and small in Oregon. P.A. Skinkis et al., Oregon State berries and produce a significant amount of University Extension Service, pub. EM 8413. webbing. Larger 1st and 2nd generation larvae Grapes: Factsheets and Publications. BC burrow into and feed on the fruit, leaving Ministry of Agriculture and Lands website hollowed out skins and seeds. Grape bunches (www.al.gov.bc.ca/grape/factsheets.htm).

Best Practices Guide for Grapes for British Columbia Growers 5.3-27