Habitat Management in Vineyards Habitat Management in Vineyards

Acknowledgements: Special thanks to all collaborating farmers, Captain Family Vineyards, Quintessa Vineyards, Foster’s Group, Ridge California, Icon States, Robert Sinsky Vineyards, Joseph Phelps Vineyards, Saintsbury Vineyards, Medlock-Ames, Spootswoode. The efforts of Ana Cecilia Galvis for assembling and formatting this manual are greatly appreciated. The following organizations provided funds to produce this manual: EPA, USDA - SARE, and Organic Farming Research Foundation (OFRF). Habitat Management in Vineyards

Habitat Management in Vineyards A growers manual for enhancing natural enemies of pests.

Miguel A. Altieri Clara I. Nicholls Houston Wilson Albie Miles

Laboratory of Agroecology http://agroecology.berkeley.edu College of Natural Resources University of California 2010 Habitat Management in Vineyards

Typical grape production in and soil-borne organisms that and environmental costs can be California is done in monocul- inhabit a vineyard system, the quite significant. Economically, tures which are expanding at a more diverse the community of in viticulture the burdens in- rapid rate resulting in the sim- pest-fighting beneficial organ- clude the need to supply crops plification of the landscape. One isms (predators, parasitoids, with costly external inputs such of the known problems with and entomopathogens) the farm as insecticides, since vineyards monocultures is that the diver- can support. deprived of functional biodiversity, abundance and activity of sity lack the capacity to sponsor natural enemies of pests is dras- In this manual we explore prac- their own pest regulation. tically decreased due to the re- tical steps to restore agricultur- moval of vegetation which pro- al biodiversity at the field and Biodiversity in vineyards includes vides critical food resources and landscape level thus breaking the vines, cover crops, weeds, ar- overwintering sites necessary the monoculture nature of vine- thropods, soil fauna and micro- for the longevity, reproduction yards and reducing their ecologi- organisms. In general the type and survival of many predators cal vulnerability. The most obvi- and abundance of biodiversity and parasites. Since the onset ous advantage of diversification in vineyards depends on three of such simplification farmers is a reduced risk of crop failure main features: have been faced with a major due to invasions by unwanted ecological dilemma arising from species and subsequent pest in- • The diversity and type the homogenization of vineyard festations. The manual focuses of vegetation within and systems: increased vulnerabil- on ways in which increased plant around the vineyard and the ity of crops to insect pests and biodiversity can contribute to permanence of these plant diseases, many of them devas- stabilizing pest population by communities tating when infesting uniform creating an appropriate eco- • The quality of soil, its organic and homogeneous large-scale logical infrastructure within and matter content, cover level monocultures. Many scientists around vineyards. and biological activity are concerned that as vineyards • The intensity of manage- expand, natural vegetation act- Biodiversity in vineyards: ment and types of inputs ing as refugia decline and conse- types and roles used depending on whether quently the contribution to pest the vineyard is conventional, suppression by biocontrol agents Biodiversity refers to all species organic or in transition. using these habitats is diminish- of plants, animals, and micro- ing. In fact many pest problems organisms existing and interact- The biodiversity components of affecting today’s vineyards have ing within a vineyard, many of vineyards can be classified in re- been exacerbated by such habi- which play important ecological lation to the role they play in the tat simplification trends. functions such as pollination, functioning of the vineyard sys- organic matter decomposition, tems. Vineyard biodiversity can One of the main ecological op- predation or parasitism of pests. be grouped as follows: tions to rectify this habitat- de These ecosystem services are cline is to increase the vegeta- largely biological; therefore their • Productive biota: the vines tional diversity of vineyards and persistence depends upon main- and other crops or animals surrounding landscapes. Plant tenance of ecological diversity in chosen by farmers biodiversity is crucial to crop the vineyards. When these natu- • Functional biota: organisms defenses: the more diverse the ral services are lost due to biolog- that contribute to produc- plants and associated animals ical simplification, the economic tivity through pollination,

Habitat Management in Vineyards

biological control (predation and the vegetational diversity of vineyard. The wasps are part of and parasitism of pests), or- the system. The relationship of the associated biodiversity. The ganic matter decomposition, both types of biodiversity com- cover crops then improve soil nutrient mineralization, etc ponents is illustrated in Figure 1. fertility (direct function) and -at • Destructive biota: weeds, in- Planned biodiversity has a direct tract wasps (indirect function). sects pests, microbial patho- function, as illustrated by the ar- Obviously the type and abun- gens, etc., which farmers aim row connecting the planned bio- dance of associated biodiversity at reducing through cultural diversity box with the ecosystem is influenced by the kind of veg- management. function box. Associated biodi- etation that surrounds the vine- versity also has a function, but it yard, with vineyards immersed The above categories of biodi- is mediated through planned bio- in a more heterogeneous land- versity can further be recognized diversity. Thus, planned biodi- scape exhibiting a more diverse as two distinct components. versity also has an indirect func- array of associated organisms. The first component, planned tion, which is realized through biodiversity, includes the vines, its influence on the associated By promoting the right type of and other crops or animals pur- biodiversity. For example, the functional biodiversity in vine- posely included in the vineyard cover crops in a vineyard provide yards it is possible to enhance by the farmer. The second com- biomass to enhance soil organic ecological processes that pro- ponent, associated biodiversity, matter and fertility, so the direct vide key services such as the ac- includes all soil flora and fauna, function of this second species tivation of soil biology, the recy- herbivores, predators, parasites, (cover crops) is to improve soil cling of nutrients, the regulation decomposers. that inhabit the quality. Yet along with the cover of pests by beneficial arthropods vineyard or that colonize from crops come parasitic wasps that and antagonists, and so on. A surrounding environments and seek out the nectar in the cov- key challenge is to identify the that thrive in the system depend- er’s flowers. These wasps are in type of biodiversity that is desir- ing on its management (use of turn the natural parasitoids of able to maintain and/or enhance chemicals or organic inputs, etc) pests that normally attack the in the vineyard in order for them

Figure 1. The relationships between planned and associated biodiversity in promoting pest regulation in vineyards.

Habitat Management in Vineyards

in density and/or a density-dependent manner, that is: natural enemies increase in intensity and destroy a larger population of the population as the density of that population increases, and visa-versa. The goal of biological control is to hold a target pest below economically damaging levels — not to eliminate it com- pletely — since decimating the population also removes a critical food resource for the natural enemies that depend on it.

Applied biological control is es- sentially a strategy to restore functional biodiversity in agroecosystems by adding, through augmentative releases of natural enemies, “missing” entomophagous insects in the crop field. Figure 2. The effects fo agroecosystem management and associated cultural practices on This practice is not commonly the diversity and abundance of natural enemies and the densities of insects pests followed in vineyards and instead farmers rely on strategies to carry out key ecological ser- through predation and parasit- aimed at conserving and enhanc- vices, and then to determine the ization. Every insect herbivore ing naturally occurring predators best practices that will encour- is attacked to some degree by and parasitoids through habitat age the desired beneficial organ- one or more natural enemies management. The idea is to at- isms. There are many agricul- (also called beneficial insects) , tract early in the season a com- tural practices and designs that thus predators, parasites, and plex of beneficials and provide have the potential to enhance pathogens act as natural control them with habitat and alterna- functional biodiversity, and agents resulting in the regula- tive food so that they can build others that negatively affect it tion of herbivore numbers in a up in numbers and remain in the (Figure 2.) particular ecosystem. This reg- farming system throughout the ulation is known as biological season. Biological control: a control defined as “the action of parasites, predators, or patho- To complete their life cycles, key ecological service in natural enemies need more vineyards gens in maintaining another or- ganism’s population density at a than prey and hosts; they also lower average than would occur need refuge sites and alterna- One major ecological service tive food. Many adult parasites provided by biodiversity in vine- in their absence”. Biological control can be self-sustaining and and predators sustain them- yards is the regulation of abun- selves with pollen and nectar dance of undesirable organisms distinguishes itself from all other forms of pest control by acting from flowering weeds or from Habitat Management in Vineyards alternative hosts or prey present Table 1. Main insect pest of vineyards and their key natural enemies (Guerra, 2010). in non-crop vegetation within or around vineyards. Research has shown that by adding plant diversity to monocultures, it is possible to create habitat conditions which favor natural enemy abundance and effectiveness. In plant diverse cropping systems there is generally an increased abundance of arthropod predators and parasitoids due to enhanced availability of alternate prey, nectar sources and suitable shelter.

Habitat management is based on the notion that one of the most powerful and long-lasting ways to minimize economic damage from pests is to boost populations of existing naturally occurring beneficial organisms by supplying them with appropriate habitat and alternative food sources.

Natural enemies of vineyard pests

Most vineyards are inhabited by a diversity of natural enemies, but their abundance will depend on whether growers use toxic pesticide and if they maintain a reasonable amount of plant diversity in the vineyard. Each main pest attacking vines has one or two natural enemies (Table 1) which if present early enough in the season and in sufficient numbers can usually keep pest populations below damaging levels.

Habitat Management in Vineyards

Leafhopper enemies: The main Mite enemies: The most impor- in the Braconid, Ichneumonid, parasitoid of leafhoppers is a tant predators of spider mites are Chalcid and Eulophid families, tiny wasp called Anagrus which other predatory mites (phyto- as well as Tachinind parasitic parasitizes leafhopper eggs, and seiid species). Predaceous mites flies. Although a new pest in in the process, it destroys them. can be released in the vineyard, California, it is known that sev- Anagrus can typically kill 90 per- but release time, rather than eral species of parasitic wasps cent of the western grape leaf- rate, seems to be a crucial factor. can parasitize the eggs, larvae hopper (WGLH) eggs present in a Fall releases of phytoseiid mites and pupae of Lobesia botrana. vineyard, whereas they rarely kill provides excellent control of spi- Trichogamma species are known more than 40 percent of the var- der mites the following season, egg-parasites of European grape- iegated leafhopper eggs, which whereas summer releases seem vine moth. Studies are needed to are laid deeper in the leaf tissue. to have little effect. Other spi- determine how early in the sea- Natural predators that feed on der mite predators although less son Trichogamma species begin leafhoppers include spiders, the effective, include six-spotted to parasitize L. botrana eggs, if whirligig mite , green lacewings thrips, minute pirate bugs, and other species of native parasites and a species of tiger fly. the lady beetle mite destroyer attack the larval or pupal stages, Stethorus picipes. and the impact these parasites Mealybug enemies: There a four have in reducing moth densities spieces of mealy bugs that attack Enemies of moth pests : and their damage. grapes although the most domi- Economically important moth nant are the grape mealybug species in grape vineyards include Conserving natural enemies and the vine mealybug which is the omnivorous leafroller, or- the most problematic. One of the ange tortrix, grape leafroller and Naturally occurring beneficials, most effective mealybug preda- the western skeletonizer. Green at sufficient levels, can take a big tors is the “mealybug destroyer,” lacewings as well as various spi- bite out of pest populations. To a lady beetle whose success re- der species are important preda- exploit them effectively, it is im- sides in its camouflage. The wax- tors of moth larva. Eggs of these portant to: like filaments of the mealybug moths are generally parasitized destroyer larvae, resembling by Trichogramma wasps and 1) identify which beneficial- or those of the mealybug, allow this the larvae by a number of wasps ganisms are present; lady beetle to feed on the mealybugs without disturbance from foraging ants. Other mealybug predators include the lady bug The following characteristics are typical of vineyards that beetle Hyperaspis sp, lacewings host plentiful populations of beneficials insects: and Cecidomyiid flies. Green and • Small fields surrounded by natural vegetation. brown lacewings can also feed • Diversified cropping systems with year-round cover crops on mealybugs. Several naturally and hedges that include perennials and flowering plants. occurring parasitoids also attack • Crops are managed organically or with low chemical in- grape mealybugs and a host of puts, including modest sulphur applications. parasitoid species introduced • Soils are high in organic matter and are biologically from other countries. Ant con- active. trol is a necessary component of • Soils covered with mulch or cover crops throughout the any mealybug biological control year. program

Habitat Management in Vineyards

2) understand their individual tilth and generous quantities of natural enemies in the crop field biological cycles and their food organic matter can stimulate a is determined by the distance to and habitat requirements; useful diversity of pest-fighting which natural enemies disperse 3) try to find out where do these soil organisms. Carefully selected into the crop from the borders. beneficials overwinter, when do flowering plants placed as strips The role of riparian habitats they appear in the field, where within the field or in margins are and especially of wild black- do they come from, what at- important sources of beneficial berry patches near vineyards in tracts them to the crop, how insects that move into adjacent enhancing the effectiveness of do they develop in the crop and fields to help regulate insect the wasp Anagrus epos in para- what keeps them in the field; pests. sitizing the grape leafhopper is 4)When do the beneficials’ criti- well known (Figure 3). It is also cal resources — nectar, pollen, Diversification of vine- known that French prunes har- alternative hosts and prey — ap- yards to enhance biologi- bor an economically insignificant pear and how long are they avail- cal control : experiences in leafhopper whose eggs provide able? Are alternate food sources Anagrus with an overwinter host California accessible nearby and at the right site. Based on this knowledge, times? Which native annuals and researchers established that Managing vegetation surround- perennials can compensate for French prunes adjacent to vine- ing vineyards to meet the needs critical gaps in timing, especially yards could also serve as over- of beneficial organisms: when prey are scarce? wintering sites for A. epos and found higher leafhopper parasit- Several studies indicate that Once most of this information is ism in grape vineyards adjacent the abundance and diversity of known, farmers can make chang- to prune tree refuges. Since the entomophagous insects within es in vineyard management to effect of prune refuges is limited a vineyard is dependent on the meet the needs of beneficials to a few vine rows downwind plants species composition of and enhance their populations . thus A. epos exhibits a gradual the surrounding vegetation. The decline in vineyards with in- distribution and abundance of To conserve and develop rich populations of natural enemies, it is important to avoid cropping practices that harm beneficials such as insecticide applications, hedge removal and herbicide use that eliminates weeds in and around fields. Instead, substi- tute methods that enhance their survival. Even small changes in farming routines can substantially increase natural enemy populations during critical periods of the growing season. The simple use of straw mulch provides hu- mid, sheltered hiding places for nocturnal predators like spiders and ground beetles. Good soil Figure 3. The role of wild blackberry as a winter habitat for Anagrus wasps providing a bridge for early spring vineyard colonization by wasps (Doutt and Nakata, 1973) Habitat Management in Vineyards creasing distance from the re fuge (Figure 4). This poses an important limitation to the use of prune trees as the colonization of grapes by Anagrus is confined to field borders leaving the cen- tral rows of the vineyard void of biological control protection. To overcome such limitation some growers have established vegetational corridors composed of flowering species that cut across the vineyard, serving as a biological highway for the movement and dispersal of natural enemies from riparian forest into the center of the vineyard. These new landscape structures enhance movement of beneficials beyond the “normal area of influence” of adjacent habitats or refuges.

In Mendocino county a 600 m corridor composed of at least 65 flowering species including fennel (Foeniculum vulgare), yarrow (Achillea millefolium), Erigeron annuus, Buddleja spp. and other flowering plants was established cutting across a vineyard. Adult Figure 4. French prune tree refuges as a source of Anagrus wasps early in the season leafhoppers exhibited a clear (Corbett and Rosenheim, 1996) density gradient reaching low- est numbers in vine rows near fluenced by the presence of the buted at intervals in or around the corridor and increasing in corridor which channeled dis- vineyards. Depending on the numbers towards the center of persal of the beneficals into ad- plant species, these “peren- the field. The highest concentra- jacent vines (Figure 6). Predator nial islands” provide shelter and tion of adult and nymphal- leaf numbers were higher in the first food resources to predators and hoppers occurred after the first 25m adjacent to the corridor parasitic wasps as well as -over 20–25 rows (30–40m) down- which probably explains the re- wintering sites from which vine- wind from the corridor (Figure duction of leafhoppers observed yards can be colonized in the 5). The abundance and spatial in the first 25 - 30 vine rows near spring. This is the approach used distribution of generalist preda- the corridor. in a vineyard in Sonoma County tors in the families Coccinellidae, where an island of flowering Chrysopidae, Anthocoridae, Other growers leave sections herbaceous annuals and peren- Nabidae and Syrphidae was in- of undisturbed habitat distri- nials was created at the center

10 Habitat Management in Vineyards

of a vineyard and which acts as a push-pull system for natural enemy species. During the 2004 season, sampling revealed that the island acts as a source of pollen, nectar, and neutral insects which serve as alternate food throughout the growing season to a vari- ety of predator and parasites, including Anagrus wasps. Catches in yellow sticky traps placed in- Figure 5. Population of leafhoppers near Figure 6. Population of predators near side the island and at various dis- (<25 m) and far from a corridor (Nicholls et (< 25m) and far from a corridor (Nicholls al, 2001) et al, 2001) tances within the vineyard, sug- gest that many natural enemies moved from the insectory island into the vineyard (up to 60 me- ters). Orius sp. and Coccinellids are prevalent colonizers at the beginning of the season, but later syrphid flies and Anagrus wasps start dispersing from the island into the vineyard (Figure 7). Parasitization of leafhopper eggs by Anagrus wasps was particularly high on vines near the island, with parasitization levels

Figure 7. Dispersal of Anagrus wasps and generalist predators from the island into de vineyard. 11 Habitat Management in Vineyards decreasing towards the center of the vineyard away from the island.

Planting cover crops to enhance natural enemies. Growers have many options to include cover crops in their vineyards (Appendix I). Among the many benefits of cover crops (protect soils from erosion, improve soil fertility, improve soil structure, and water holding capacity) the provision of habitat for predator Figure 8. The multiple benefits of cover crops in vineyards and parasitic arthropods stands out (Figure 8). Researchers tion dries early in the season or well-dispersed alternative food have reported lower popula- is mowed or plowed under at source, as well as microhabi- tions of mites in vineyards with the beginning of the growing tats, for a diverse community of cover crops due to enhanced season, leaving vineyards in late natural enemies. In a Mendocino populations of predaceous mites spring and summer as virtual vineyard maintaining floral di- (Figure 9), although improved monocultures without floral diversity throughout the grow- water penetration, greater soil versity. For this reason new habi- ing season using a mixture of fertility and reduced dust associ- tat management approaches buckwheat and sunflower re- ated with cover crops may also emphasize the maintainance of duced substantially the abun- be responsible for observed ef- a flowering cover that blooms dance of western grape leafhop- fects on mites. Growers report early and throughout the season pers and western flower thrips experiences of reduced leafhop- in order to provide habitat and a while the abundance of associ- per problems when cover crops are planted in lieu of conventional insecticide applications. In many cases such biological suppression has not been sufficient from an economic point of view. Part of the leafhopper reduction found in cover-cropped vineyards may be due to the reduced vigor resulting from the nutrient and water competition, as it has been found out that when vine vigor is reduced, leafhopper populations are also reduced.

The low effectiveness of winter cover crops to reduce pests, is Figure 9. Effect of a sudan grass cover on Willamette mite abundance (Flaherty, due to the fact that this vegeta- 1969) 12 Habitat Management in Vineyards ated natural enemies increased on vines were similar in the se- er crop rows. During the second (Figure 10). In the same vineyard, lected cover-cropped rows. One week such nymphal decline was mowing every other row the week after mowing, numbers of even more pronounced coincid- cover crops forced movement nymphs declined on vines where ing with an increase in numbers of Anagrus wasps and predators the cover crop was mowed, of Anagrus wasps in the foliage into the vines. Before mowing, coinciding with an increase in (Figure 11). leafhopper nymphal densities Anagrus densities in mowed cov-

Figure 10. Reduction of leafhopper densities in a vineyard with a buckwheat - sunflower cover crop (Nicholls et al, 2000)

Figure 11. Effects of moving a flowering cover crop on leafhopper nymphal densities Buckwheat and numbers of Anagrus wasps (Altieri et al, 2005)

New approaches for floral group has devised a new strategy cies that flower in sequence resource provisioning with of Floral Resource Provisioning (Figure 12). Species tested cover crops (FRP) testing the potential of include ‘Annual Buckwheat’ several flowering plants to- en (Fagopyrum esculentum), ‘Lacy Working collaboratively since hance biological control of leaf- Phacelia’ (Phacelia tanacetifolia), 2007 with a number of com- hoppers and other pests. The ‘Sweet Alyssum’ (Lobularia ma- mercial growers in Napa and project measured the impact of ritima), ‘Bishops Weed’ (Ammi Sonoma counties our research intercropping of five plant spe- majus) and ‘Wild Carrot’ (Daucus 13 Habitat Management in Vineyards

Wild Carrot

Figure 12. Flowering sequence of five cover crops plants ensuring year - round refuge, pollen and nectar for natural enemies.

Figure 13. Sequential and spatial design of flowering strips within vineyards.

14 Habitat Management in Vineyards carota) which are deployed in the vineyard in the sequential and spatial design described in appendix II, includes information on seeding times, rates, and sowing depths for the five flowering plant species (Figure 13).

So far reseach results from trials conducted in various vine- Average leafhooper nymphs per leaf leafhooper Average yards has shown that when the weather allows for good establishment of flowering ground covers this results in a consistent Figure 14. Peak leafhopper nymph density at all Grower Trial sites in 2009 decreasing trend in pest densities. At research sites with the highest pest pressure and good cover crop establishment, there appears to be a significant effect of the flowers. In 2009, Grower trials revealed that leafhopper nymph densities were lower in 6 of 7 blocks with the flowering ground cover plots when compared to farmer controls without cover crops, and these diffe- rences were especially notice- Figure 15. Predator diversity and abundance on ground covers at Fosters Grace (2009) able at three separate research sites where pest densities reached greater than 2 nymphs per leaf (Figure 14)

Sweep netting of the flowering covers showed that these plants attracted a great diversity of generalist predators reaching substantial abundance levels when compared to resident vegetation. As seen in Figure 15, the predator species guilds changed with the species of flowers and Figure 16. Predator abundance in the vine canopy in seven surveyed vineyards as the season progressed and certain flowers senesced, pred- of seven vineyards many preda- ers than in control plots. These ators moved to new flowering tors reached higher densities on predators detected in the vine plants in the sequence. In four the canopy in blocks with flow- canopy of the treatment plots 15 Habitat Management in Vineyards were also found in the flowers, • Create an inventory of ex- of that infrastructure are flower suggesting that these arthropods isting habitat and plant re- resources. When choosing flow- move from the covers to the sources in and around the ering plants to attract beneficial vines (Figure 16). More detailed vineyard (are there sufficient insects it is important to note analysis is needed to determine floral resources, are flow- the size and shape of the blos- which species of predators are ers attractive to key natural soms, because that’s what dic- attracted to which flowers. For enemies, do predators and tates which insects will be able example, the minute pirate bug parasites move from flowers to access the flowers’ pollen and Orius is predominantly found to the vines?) nectar. For most beneficials, in- on buckwheat and wild carrot • Do existing plant habitats and cluding parasitic wasps, the most but rarely on P. tanacetifolia, associated flowers match the helpful blossoms should be small but more of these relationships needs of naturally occurring and relatively open. Plants from between flowers and predators natural enemies? the Compositae, Lamiaceae, and need to be determined. • Is there a need to add lacking Umbelliferae families are espe- flower resources and habi- cially useful (Appendix IV). Guidelines for implement- tat with additional plants ing a habitat management species in the form of cover Timing of flower availability is as strategy in vineyards crops, flower strips, hedge or important to natural enemies as border insectory plantings? blossom size and shape. Many The most successful examples of What plant species should beneficial insects are active only habitat management systems are be added? as adults and only for discrete those that have been fine-tuned • Do these added plant re- periods during the growing sea- by farmers to fit their particu- sources provide year round son; they need pollen and nec- lar circumstances as each farm shelter and nectar sources tar during these active times, is a unique ecosystem with its either floral or extrafloral particularly in the early season own associated biodiversity and to key beneficials? Do they when prey are scarce. One of the set of environmental conditions bloom at a time that best easiest ways farmers can help is tied to the geographic location meets the needs of benefi- to provide beneficials with mix- and overall management. Before cials for pollen, nectar or al- tures of plants with relatively implementing a habitat diversifi- ternate hosts? Have these long, overlapping bloom times. cation strategy specific to fit the plants resources been plant- needs of a particular farm, it is ed at optimal spacing within Useful references important to follow same basic the vineyard or at the right steps (See also Appendix III for distance of vineyard. Altieri, M.A., Nicholls, additional tips). C.I. (2004). Biodiversity and pest • Identify which key natural Diverse and complex vineyards management in agroecosystems. enemies are present in the may be harder to manage, but Binghamton USA: Food Products vineyard (on the canopy and when properly implemented, Press. on the soil), on weeds, cover habitat management leads to Altieri, M.A., Nicholls, crops and the surrounding the establishment of the de- C.I, Ponti, L. and York A.(2005). vegetation. sired type of plant biodiversity Designing biodiverse pest resil- • Learn more about the biolo- and unique ecological infrastruc- ient vineyards through habitat gy of these beneficial arthro- ture necessary for attaining op- management. Practical winery pods and what they need to timal natural enemy diversity and vineayard. May-June, 6p. thrive. and abundance. A key feature 16 Habitat Management in Vineyards

Altieri, M.A. and C.I. Tetranychidae) densities. Thrupp, L.A., M. J. Nicholls 2005 Manage insects Ecology Letters, 50, 911-916. Costello and G. McGoruty. on your farm: a guide to eco- Guerra, B.( 2010). Insect (2008). Biodiversity conserva- logical strategies. Sustainable pest management for organ- tion practices in California vine- Agriculture Network, Beltsville. ic vineyards. Wine Bussiness yards: learning from experienc- Handbook Series Book 7.. Monthly, July. es. CA Sustainable Winegrowing Ambrosino, M. (2005). Gurr, G.M., Wratten, S.D., Alliance. Practical guidelines for establish, Altieri, M.A. (2004). Ecological Thrupp, L. A. (2003). maintaining, and assessing the engineering for pest manage- Growing organic winegrapes. An usefulness of insectary planting ment: advances in habitat introduction Handbook for grow- on your farm. IPPC-Oregon State manipulation for arthropods. ers. Fetzer Vineyards, Hopland, University, Corvallis. Wallingford UK: CABI Publishing. CA. Corbett, A., Rosenheim, Ingels, C.A. et al 1998 J.A. (1996). Impact of a natu- Cover cropping in vineyards: a ral enemy overwintering refuge grower’s handbook. UC Division and its interaction with the sur- of Agriculture and Natural rounding landscape. Ecological Resources. Publication 3338. Entomology, 21, 155-164. Landis, D.A., Wratten, Daane, K.M., Costello, S.D., Gurr, G.M. (2000). Habitat M.J. (1998). Can cover crops re- management to conserve natu- duce leafhopper abundance in ral enemies of arthropod pests vineyards? California Agriculture, in agriculture. Annual Review of 52, 27-33. Entomology, 45, 175-201. Doutt, R.L., Nakata, J. McGourty, G. (2004). (1973). The Rubus leafhop- Cover cropping systems for or- per and its egg parasitoid: an ganically farmed vineyards. endemic biotic system useful Practical Winery and Vineyard. in grape-pest management. September-October, 7p. Environmental Entomology, 2, Nicholls, C.I., Parrella, 381-386. M.P., and Altieri, M.A. (2000). English-Loeb, G., Rhainds, Reducing the abundance of leaf- M., Martinson, T., Ugine, T. hoppers and thrips in a north- (2003). Influence of flowering ern California organic vineyard cover crops on Anagrus parasit- through maintenance of full sea- oids (Hymenoptera: Mymaridae) son floral diversity with summer and Erythroneura leafhoppers cover crops. Agricultural and (Homoptera: Cicadellidae) in Forest Entomology, 2, 107-113. New York vineyards. Agricultural Nicholls, C.I., Parrella, and Forest Entomology, 5, M., and Altieri, M.A. (2001). The 173-181. effects of a vegetational corridor Flaherty, D . L. (1969). on the abundance and disper- Ecosystem complexity and the sal of insect biodiversity within Willamette mite, Eotetranychus a northern California organic willamettei (Acarine: vineyard. Landscape Ecology, 16, 133-146.

17 Habitat Management in Vineyards

Appendix I.

Cover cropping options for vineyards

The majority of growers use an annually tilled and seeded system of cover crops to conserve moisture in their vineyards. Cover crops are planted in the fall, al- lowed to grow until some point in the spring (usually when the cover crops is flowering) when the ground can be easily cultivated, and then mowed and tilled into the soil. Cover crop species typically used in this system include annual small grains (barley, oats, triticale), winter peas, common vetch, bell beans, daikon radish, Persian clover and others

Other growers use a no-till system with annual cover crops which are tilled initially and seeded with species that will reseed themselves on an annual basis. Thereafter, the vineyards are mowed in spring and early summer. Tillage is restricted to only beneath the vines. Subterranean clovers, rose clovers, crimson clover, red clover, berseem clover, bur medic, bolansa clover, and Persian clover are all suited for this farming system. Grasses that can be used include Blando brome and Zorro fescue.

Perennial species are commonly used in vineyards planted on fertile sites. Many of the perennial grasses are very competitive with grape vine roots, and will have a devigorating effect on the vineyard. This may be- desir able if the vineyard is seriously out of vegetative balance. There is a range of cover crops that vary from being slight ( fine fescues) to intermediate in their competitiveness (perennial rye, orchard grass , tall fescue), to very competitive such as perennial rye grass, tall fescue, and -or chard grass. Irt may be desirable to include perennial le- gumes in a sward of grasses, as they will supply nitrogen for the grasses but will also provide habitat for generalist predator and parasitoid insects.

18 Habitat Management in Vineyards

Appendix II. Agronomic recommendation for establishment of flowering strips within vineyards.

Species Location Rate Depth Sown

Option Fall (Oct. 15) Spring (May 1)

19 Habitat Management in Vineyards

Appendix III.

Guidelines to be considered when implementing habitat management strategies in vineyards • Select the most appropriate plant species; • Determine the most beneficial spatial and temporal arrangement of such plants, within and/or around the fields; • Consider the spatial scale at which the habitat enhance- ment operates (e.g., field or landscape level); • Understand the predator-parasitoid behavioral mecha- nisms influenced by the habitat manipulation; • Anticipate potential conflicts that may emerge when adding new plants to the agroecosystem (i.e., in California blackberries, Rubus sp., around vineyards increase po pulations of the wasp Anagrus epos, a parasotoid of the grape leafhopper Erythroneura spp., but can also enhance abundance of the sharpshooter, which serves as a vector of Pierce’s disease); • Develop ways in which the added plants do not up- set other agronomic management practices, and select plants that have multiple effects, such as improving pest regulation while at the same time contributing to soil -fer tility and weed suppression.

Enhancing Above ground Biodiversity: A Checklist For Viticulturalists

• Diversify the vineyards by including more species of crops and livestock. • Use legume-based cover crop mixtures • Establish every 2,3, 5 vine rows strips of flower mixtures that bloom sequentially • Leave strips of wild vegetation at field edges. • Plant a diversity of trees and native plants as windbreaks or hedgerows. • Establish corridors that cut across the vineyard and that connect to riparian or other natural forest. • Leave areas of the farm untouched or purposely planted with flowering shrubs and herbs as habitat for plant and animal diversity. • Provide a source of water for birds and insects.

20 Habitat Management in Vineyards

Appendix IV. Flower families useful to attract beneficial insets in veneyards

Plants with flowers provide essential food for natural enemies that ensures- theirsur vival, but they also influence their reproductive capacity and natural enemy longevity. To retain beneficials in a vineyard is essential to have both annual and perennial plants blooming throughout the growing season so that an abundant food supply for natural enemies is readily available. It is also critical for flowers to be accessible to natural enemies and there are certain flower types more accessible as food source. Plants in the carrot family (Umbelliferae) are suitable because they have exposed nectarines (nectar-produc- ing glands). Color is also important, yellow, orange, and withe flowers seem to be particularly attractive to a range of parasitoids. The following plants within various families are suggested as useful for attracting natural enemies:

List of some useful flowering plants that can be used within or around vineyards to attract natural enemies

Brassicacea - Mustard family: sweet alyssum ( Lobularia maritima), wild mustard ( Brassica kaber and other Brassica spp) , yellow rocket ( Barbarea vulgaris) Compositae-Aster family: coneflower Echinacea spp, Coreopis spp, Cosmos, tansy (Tanacetum vulgare), yarrow (Achillea spp), blackeyed susan (Rudbeckia hirta), Prairie coneflower (Ratibida columnifera) Umbelliferae - Carrot family: bishop’s weed (Ammi majus), caraway (Carum carvi), coriander (Coriandrum sativum), dill (Anethum graveolens), fennel (Foeniculum vulgare), wild carrot (Daucus carota), bisnaga (Ammi visnaga), wild parsnip (Pastinaca sativa) Leguminosae - Pea family: alfalfa (Medicago sativa), vetch (Vicia atropurpureum), V. vilolosa , V. cordata , V. benhali, faba (Vicia faba) , sweet clover (Melilotus spp), clovers ( Trifolium fragiferum, T. subterraneum, T. hirtum, T. incarnatum), Breseem clover (Trifolium alexandrinum), common pea (Piusm sativum) Lamiaceae - Mint family: blue catmint (Nepeta faassenii), Russian sage (Perovskia atriplicifolia) Other plants: baby blue eyes (Nemphila menziesii), buckwheat (Fagopyrum esculentum), cinquefoil (Potentilla spp) and milkweeds (Asclepias spp), Lacy phacelia (Phacelia tanacetifolia).

As an added benefit, many of these flowers are excellent food for bees, enhancing honey production, or they can be sold as cut flowers, improving farm income.