Altieri_2010_habitat_management_in_vineyards by lanyuehua

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									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 biodiver-
sity, 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-de-
                                                                                 pendent manner, that is: natu-
                                                                                 ral 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 criti-
                                                                                 cal food resource for the natural
                                                                                 enemies that depend on it.

                                                                                       Applied biological control is es-
                                                                                       sentially a strategy to restore
                                                                                       functional biodiversity in agro-
                                                                                       ecosystems by adding, through
                                                                                       augmentative releases of natural
                                                                                       enemies, “missing” entomopha-
                                                                                       gous 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 in-
                                                                                       stead 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
                                                                                       To complete their life cycles,
key ecological service in parasites, predators, or patho- natural enemies need more
vineyards                                    gens in maintaining another or-
                                             ganism’s population density at a than prey and hosts; they also
                                                                                       need refuge sites and alterna-
One major ecological service lower average than would occur tive food. Many adult parasites
provided by biodiversity in vine- in their absence”. Biological con- and predators sustain them-
yards is the regulation of abun- trol can be self-sustaining and selves with pollen and nectar
dance of undesirable organisms distinguishes itself from all other from flowering weeds or from
                                             forms of pest control by acting

                                                                                    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 condi-
tions which favor natural enemy
abundance and effectiveness. In
plant diverse cropping systems
there is generally an increased
abundance of arthropod preda-
tors and parasitoids due to en-
hanced 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 popula-
tions of existing naturally oc-
curring beneficial organisms by
supplying them with appropri-
ate habitat and alternative food
sources.

Natural enemies of vine-
yard pests

Most vineyards are inhabited by
a diversity of natural enemies,
but their abundance will de-
pend on whether growers use
toxic pesticide and if they main-
tain 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 suf-
ficient numbers can usually keep
pest populations below damag-
ing 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 mealy-
bugs 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 substantial-
ly increase natural enemy popu-
lations 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 im-
portant 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 veg-
etational corridors composed of
flowering species that cut across
the vineyard, serving as a biolog-
ical highway for the movement
and dispersal of natural enemies
from riparian forest into the cen-
ter 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 fen-
nel (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 ene-
                                                                                           my species. During the 2004 sea-
                                                                                           son, sampling revealed that the
                                                                                           island acts as a source of pollen,
                                                                                           nectar, and neutral insects which
                                                                                           serve as alternate food through-
                                                                                           out the growing season to a vari-
                                                                                           ety of predator and parasites, in-
                                                                                           cluding 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 par-
                                                                                           ticularly 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 en-
hance 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 di-                 versity 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 conven-
tional insecticide applications. In
many cases such biological sup-
pression has not been sufficient
from an economic point of view.
Part of the leafhopper reduction
found in cover-cropped vine-
yards may be due to the reduced
vigor resulting from the nutri-
ent 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.


1
                                                                                          Habitat Management in Vineyards


carota) which are deployed in




                                           Average leafhooper nymphs per leaf
the vineyard in the sequential
and spatial design described in
appendix II, includes informa-
tion on seeding times, rates, and
sowing depths for the five flow-
ering plant species (Figure 13).

So far reseach results from
trials conducted in various vine-
yards has shown that when the
weather allows for good esta-
blishment 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 densi-
ties. 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 com-
pared to farmer controls with-
out 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 gen-
eralist predators reaching sub-
stantial abundance levels when
compared to resident vegeta-
tion. 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

                                                                                                                             1
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
                                          What plant species should         beneficial insects are active only
The most successful examples of
                                          be added?                         as adults and only for discrete
habitat management systems are
                                      •   Do these added plant re-          periods during the growing sea-
those that have been fine-tuned
                                          sources provide year round        son; they need pollen and nec-
by farmers to fit their particu-
                                          shelter and nectar sources        tar during these active times,
lar circumstances as each farm
                                          either floral or extrafloral      particularly in the early season
is a unique ecosystem with its
                                          to key beneficials? Do they       when prey are scarce. One of the
own associated biodiversity and
                                          bloom at a time that best         easiest ways farmers can help is
set of environmental conditions
                                          meets the needs of benefi-        to provide beneficials with mix-
tied to the geographic location
                                          cials for pollen, nectar or al-   tures of plants with relatively
and overall management. Before
implementing a habitat diversifi-         ternate hosts? Have these         long, overlapping bloom times.
                                          plants resources been plant-
cation strategy specific to fit the
                                          ed at optimal spacing within      Useful references
needs of a particular farm, it is
                                          the vineyard or at the right
important to follow same basic
                                          distance of vineyard.                 Altieri, M.A., Nicholls,
steps (See also Appendix III for
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

1
                                                                                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.

                                                                                                            1
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 in-
     clude 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 clo-
     vers, rose clovers, crimson clover, red clover, berseem clo-
     ver, 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 com-
     petitive 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.




1
                                                              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)




                                                                                          1
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 en-
        hance 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.


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                                                                       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 their sur-
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 en-
emies 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 particu-
larly 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.




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