Ch 8 Hazards, Pests and Diseases Flashcards

Question

# Hazards, Pests, Diseases What are management options for Phylloxera?

Answer 1

Plant on sandy soil - immune to phylloxera Use American root stock hybrids

Answer 2

Use of American rootstocks ○ v berlandieri, v rupsetris, v riparia How work: they form hard corky layers that surround eggs, sealing the wounds and preventing bacteria/fungi Side effect - undesireable aromas -> led to grafting of euro varieties onto American rootstocks Secondary issue: ○ Grafting onto single var of American rootstock -> lacked lime content resistance common in calcareous soil of Europe->vines got chlorosis, turning leaves yellow and reducing photosynthesis = reduced yield/quality ○ Solution - use rootstock hybrids to balance level of protection from phylloxera and resistance to limestone Long term solution: ○ Has led to new rootstock hybrids with complex parentage -> address multiple issues - phylloxera, nematodes, extremes of soil pH, water stress, salinity and control vine vigor

Answer 3

○ Microscopic worms common in soil, too small to be seen ○ 2 most common - root knot nematode and dagger nematode ○ Some cause damage by feeding off vine roots, signif reducing vigor and yields = slow, gradual decline; others transmit viral diseases -> fanleaf virus spread by dagger nematode ○ Spread - already in soil or introduced by unclean nursery stock, irrigation water or machinery Management options: ○ Can only be managed, not eliminated - few options ○ Lab soil analysis to det number/type present ○ Fumigate soil - chems formerly used, now mostly banned; plough in cover crop of mustard plant -> has compounds that work as bio-fumigants -> kill nematodes ○ Use nematode-resistant rootstock - most popular - heat treated to kill nematodes. Ex - Ramsey and Dog Ridge (v champini)

Answer 4

○ Several different moths feed on vine flowers/grapes ○ have several generations per season -> attack flowers and grapes later in season ○ Wounds created vulnerable to bacteria/fungi incl botrytis -> can result in signif crop loss ○ Most common - light brown apple moth (Australia); grapevine moth (S Europe); grape berry moth (cent and east North America); some accidentally imported to new areas -> euro moth to Napa in 2009 (eradicated in 2016) Management options: ○ Biological controls § Bacteria - bacillus thuringiensis - produces substance toxic to moths § Pheromone capsules - disrupt mating via sexual confusion § Natural predators - parasitic wasps, green lacewings, some spiders ○ Insecticides

Answer 5

○ Pacific spider mite most destructive in CA; red spider mite and 2 forms of yellow spider mites are in Europe ○ Feed on surface cells of leaves -> leaf discoloration -> reduced photosynthesis, delayed ripening and reduced yields ○ Thrive in dusty conditions - most damaging when vines are water stressed Management options: ○ Make environment inhospitable - use sprinklers and/or cover crops to reduce dust ○ Encourage predatory mites by planting host species ○ Pesticides - general pesticides may kill beneficial mites; specific pesticides can be applied but are expensive

Answer 6

○ Can destroy entire crop - feed on grapes as they ripen ○ Worst in isolated areas where they are only food source ○ Do physical damage to grapes, also allows bacteria/fungi to enter bunches -> rot ○ Starlings common species that attack vines Management options: ○ Netting - cost can be justified in high value areas - eg. Mornington Peninsula ○ Bird scarers/noises - must be rotated to avoid birds getting used to them ○ Falcons - deter birds

Answer 7

○ Deer, rabbits, kangaroos, racoons, wild boar and baboons ○ Eat shoots, grapes and leaves - break skin of grapes = rot; damage trellising ○ Reduce yield, reduce quality, increase costs Management options: ○ Fencing - need to be sufficiently high and sturdy to work

Answer 8

Fungal Viral Bacterial

Answer 9

**Attack green parts/bunches:** Powdery mildew Downy mildew Grey rot **Attack woody parts:** Eutypa Dieback Phomopsis Cane and Leaf Spot ESCA

Answer 10

Common name: Oidium tuckeri Caused by fungus - Erysiphe necator ○ specific to grapevines - especially vitis vinifera (american species less affected) ○ Mid-1800s came to Europe - one of most widespread in world ○ Some var more susceptible - Chard, CS; PN and Riesling less prone

Answer 11

○ Stays on buds/canes over the winter -> attacks young green parts of vine ○ Affected parts get dull grey patches and become black patches ○ Damage young shoots, inflor and grapes -> reduce yield ○ Grapes can also split at veraison -> other infections ○ Growth rate of powdery mildew det by temp -> optimum ~25°C - **thrives in shady conditions** ○ Does not require high humidity, unlike other mildews -> can spread in rel dry conditions esp in dense, shady canopies Management options: ○ Best = Keep **open canopy** to reduce shade and density ○ **Sulfur** - prevent and treat disease -> growers spray vines from a few weeks after budburst and up to veraison; IMPORTANT TO SPRAY EARLY - easier to prevent than contain once it starts ○ **Systemic fungicide** - penetrate green tissue of vine (rain doesn’t wash off). Fungus can become resistant to some fungicides -> only one application/yr

Answer 12

○ Peronospora - water mold that lives w/in vine tissue - not on surface ○ Introduced from N American in last part of 1800s - now common in most regions

Answer 13

○ Attacks green parts of vine - esp young leaves and flowers = reduces yield by defoliating vine ○ Grapes can also be affected, but less important than threat of defoliation ○ Needs rainfall and warm temps - 20°C to spread ○ High risk periods - warm springs, stormy/warm summers ○ Symptoms - yellow, circular "oil spots" and then white downy fungal growth on underside of leaves Management options: ○ Bordeaux Mixture - copper sulfate and lime spray - prevent spread; protection only lasts until 20mm rain falls *ONLY OPTION FOR OV*; EU looking to reduce use to prevent build up of copper in soil ○ Fungicides ○ Good drainage and open canopy that dries quickly

Answer 14

○ Botrytis cinerea fungus that can cause signif damage to fruit = loss of yield/quality (Color, body, aroma/flavor) ○ Spores live in vineyard and become active in periods of rain/high humidity ○ Affected fruit selected out at harvest ○ Grapes vulnerable if any point of entry (grapes rub together, punctured by birds/insects) -> infects entire bunch ○ If flowers affected -> stays dormant in grape and re-emerges after veraison ○ Most at risk - var with tight bunches/thin skins - semillon, SB, PN Management options: ○ Most important options - var selection - pick var with small grapes/thick skins (PV); protect grapes from other pests ○ Open canopy, remove leaves around bunches reduces spread ○ Fungicides - copper and sulfur sprays not effective, but others work; apply at key points in season - when flowering almost complete, end of grape formation, bunch closure (when grapes in bunch large enough to touch), veraison-> fungus can develop resistance ○ Antagonistic bacteria - bacillus subtilis

Answer 15

○ Fungal trunk disease aka Dead Arm ○ Leads to rotten wood and can affect entire vineyards -> signif reduces yield and kills vines over 10yrs ○ Spores spread by wind over long distances -> infection happens via pruning wounds in mod temps esp during rain ○ Symptoms seen in spring - stunted shoot growth and yellow leaves ○ Var susceptible - Gren, CS, SB ○ Widespread, but heavy in S Australia, sw france, CA Management options: ○ Hard to control ○ Late pruning and fungicide on pruning wounds can work ○ Affected trunks cut back to 5-10cm beyond visible symptoms and treat w/ fungicide; dead wood must be burned to avoid spores spreading ○ Biological controls - bacillus subtilis - can work ○ If plant heavily affected -> retrain from a "sucker" - shoot that grows from base of vine which reduces yield for 2 yrs - or replant

Answer 16

○ Fungal disease that causes reduced yield ○ Especially in cool yrs w/ wet springs followed by humidity and mod temps ○ Infected canes whiten and break off easily; shoots from these canes develop brown cracks at their bases; leaves also impacted ○ Grenache very susceptible, CS less prone Management options: ○ Fungicides applied 3 weeks after budburst and then every 2 weeks if wet cond continue ○ Diseased/dead wood removed during pruning and burned ○ Canopy management to improve air flow can reduce risk

Answer 17

○ Complex fungal disease caused by group of orgs prevalent in warmer/drier climates (Europe/CA) ○ Enters vine via pruning wounds ○ Symptoms - striping of leaves and spotting inside wood ○ Reduces yield and kills vine in a few yrs Management options: ○ Focus is on prevention -> no chemical controls ○ Source disease-free stock, less harsh pruning techniques, not pruning in rain, remove prunings promptly from vineyard, disinfect pruning wounds ○ Research underway on biologic controls - bacillus subtilis

Answer 18

Pierce's disease Grapevine yellows

Answer 19

○ Originated in S USA, central america - common in CA ○ Rapidly kills vine ○ Bacteria lives in and clogs sap channels -> grape shriveling, dropping leaves and death of vine in 1-5yrs ○ Symptoms unclear - vines need to be lab tested ○ Spread more widely by glassy winged sharpshooter since 1980s - acts as vector (organism that transmits disease) ○ Var susceptible - PN, Chard Management options: ○ No chem controls ○ Control by reducing # of vector -> remove vines close to riverbanks which are blue-green sharpshooter habitats ○ Chem insecticides ○ Intro wasp species that feeds on sharpshooter eggs ○ Strict quarantine rules for movement of plants ○ Development underway of Pierce's disease resistant vines

Answer 20

○ Group of bacterial diseases ○ No known treatment ○ Spread by vectors - leafhoppers and nurseries selling untreated, diseased stock ○ Most common in Europe - flavescence dorée - spread in France in latter part of 20th century, also in Germany, s Europe, NY State and Australia (different form) ○ Symptoms - delayed budburst, drooping posture (new shoots fail to become woody) and canopy turns yellow (white var) and red (black var) ○ Some strains, vine dies in others it can recover; bacteria can live in a range of plants, including cover crops ○ Chard and Riesling most susceptible ○ Signif reduces yields and lowers grape qual - high acid/low sugar Management options: ○ No controls vs bacteria ○ Focus on controlling vector - insecticides can control leafhoppers; remove plants/cover crops that host the insects ○ Best practice in nursery - bathe pruning wood in hot water to kill disease

Answer 21

Fanleaf virus Leafroll virus

Answer 22

○ Group of diseases, widespread ○ Early shoot growth stunted, canes grow in distorted ways and leaves very pale, malformed and look like fans ○ Effects vary widely -> from little to losing most of crop in susceptible var - CS ○ Spread signif by move to grafted vines after phylloxera and accidental use of infected plant material; also spread slowly by dagger nematode Management options: ○ No cure and eventually affected vines must be removed and replaced - costly ○ Before vineyard replanted -> soil tests should be done to check for dagger nematodes and only virus-tested, clean planting material should be used

Answer 23

○ Group of diseases widely present around world ○ Spread by grafting and by mealy bugs - pest in S Africa, Med, Argentina and parts of CA ○ Does not kill vines -> reduces yield by up to 1/2 and impacts quality ○ Slows growth of roots and shoots; surviving fruit can take several add'l weeks to ripen -> have more acid, less color and lower sugar; overall vine health also affected -> stores less carbs ○ Downward rolling of leaves in fall - leaves change color in autumn -> red for black var and yellow for white var ○ Needs lab testing - symptoms not always clear; some vines and rootstocks can carry virus asymptomatically Management options: ○ No cure - only action is to remove unproductive and replant ○ Nurseries can screen for virus ○ Open canopies - reduce mealy bugs which like humid environ ○ Encourage mealy bug natural predators - ladybugs, lacewings ○ Spraying not effective - waxy coating of bug

Ch 8 Hazards, Pests and Diseases Flashcards

(47 cards)