Ch 8 Hazards, Pests and Diseases Flashcards
Hazards, Pests, Diseases
What are the 9 main hazards?
Water related:
* drought
* too much water
* untimely rainfall
* freeze
* frost
* hail
Heat/light related
* Sunburn
* Fire
* Smoke taint
Hazards, Pests, Diseases
What is minimum amt of water needed by vines (cool vs warm climate)?
Cool - min 500mm
Warm - min 750mm
Hazards, Pests, Diseases
How does drought affect vines?
What are management options for drought?
Effect on vine:
○ Stomata on underside of leaves close to conserve water-> reduced phs -> impact size of vine, reduced grape size, ripening slows = lower yields and unripe grapes
○ If prolonged -> vines lose leaves and die
○ If extreme, regions that rely on irrigation may be restricted -> can kill entire vineyards (Olifants River SA)
Management Options: ○ Irrigation - consider as part of vineyard establishment; can be installed later but much more \$\$/complex; restricted in parts of EU ○ Drought-resistant rootstock (at vineyard estab) - ex v rupestris and v berlandieri 110R and 140R ○ Drought tolerant grape var (Garnacha)
Hazards, Pests, Diseases
What are impacts of too much water?
What are management options?
By timing/season
Impacts:
○ Summer - excessive vine growth -> compete with grape ripening and too much shade
○ Fungal disease pressure - high humidity
○ Waterlogging - non free-draining soils -> reduce amount of 02 avail to roots = slow growth and can eventually kill vine; compaction of soil -> hard to work and uncontrolled runoff
Management options:
* If in area of regular high rain -> plan when planting vineyard -> slope or free-draining soil or by making drainage system
Hazards, Pests, Diseases
What are impacts of untimely rainfall at key parts of growing cycle?
What are management options?
Timing impacts:
○ During pollination -> coulure or millerandage = reduced yields and can lower quality
○ Summer - slow fruit ripening
○ Harvest - heavy rain -> swollen grapes = lower quality, diluted sugar levels; grapes split = grey rot; makes harvest more difficult (esp machines on clay soils)
Management options:
○ Nothing can be done about timing of rain; but choice of site, condition of soil, grass the land bet vines, ensure some drainage
○ Monitor weather forecasts - early harvest -> less ripe fruit or take chance on weather improving
Hazards, Pests, Diseases
What are concerns about freezing conditions, what areas most impacted?
What are management options?
Concerns/areas impacted:
○ Temps <-20°C can damage or kill vines
○ Graft site most at risk in freeze (if above ground), canes/cordons next at risk
○ Frost can kill canes or cordons and/or kill all parts of vine above ground = reduced yield = replace vine
○ Areas with strong continental climates most affected - Canada, Washington, China
Management options:
* Site selection - Hillsides can be up to 5°C warmer than valleys, sites near large or deep bodies of water get moderated, plant vines where snow most accum -> snow insulates vine
* Grape Variety - plant freeze resistant var - Riesling/CS; some S Amer and Mongolian (v amurensis) and hybrids are very winter tolerant (e.g. Concord - v labrusca - can tolerate to -30°C
* Protect vines - build up soil around graft (hilling up); bury vines in extreme cond (costly/labor intensive); prune vines to have several trunks -> if some killed, can be replaced
Hazards, Pests, Diseases
How/when do frosts happen?
What is the impact and how does it vary cool vs warm climate?
○ Happen when cold air <0°C collects at ground level -> freezes water in vine’s growing buds and shoots; cold winds blowing thru vineyard also dangerous
○ If happens to newly burst buds or young shoots -> kills them = major impact on yields
○ Cool climate - they are vulnerable, tho vines delay budburst and growth until temps reach avg air temp >10°C
○ Warm climate - vine starts to grow and impacted if temps drop; if buds/shoots killed->vine puts out more shoots from secondary buds->less fruitful and take longer to ripen = potential problems in fall from rain or frost)
Hazards, Pests, Diseases
What are the 2 types of frost and how do they happen?
What are the 2 categories of management action?
2 types of frost:
○ Advective - caused by large vol of cold air moving in from cold areas
○ Radiative - heat lost on still, cool nights ->amt of heat lost depends on cloud cover (cloudless loses more heat) and wind (windless lets freezing air dev above surface -> freezing cold air collects in valley bottoms since cold air heavier than warm
Management actions:
* actions that reduce the risk
* actions that address frost when it happens
Hazards, Pests, Diseases
What is advective frost?
Frost that forms when cold air mass from very cold areas moves over region
Hazards, Pests, Diseases
What is radiative frost and what factors effect it?
Frost that forms due to heat lost on still, cool nights
* amt of heat lost depends on cloud cover (cloudless night cool faster) and wind (lack of wind lets freezing air develop just above land surface)
* freezing air collects in valley bottoms since cold air is heavier than warm
Hazrds, Pests and Diseases
How do vines react to frost and what is the impact?
Vines grow shoots from secondary buds
* Less fruitful
* Take longer to ripen
Hazards, Pests, Diseases
What are management actions to proactive reduce risk of frost?
○ Site selection - avoid areas with frost pockets and choose hillsides where cool air drains away
○ Delaying pruning - postpones budburst to warmer months; if buds at end of canes get frosted they can be
removed
○ Choose late bud var (Riesling)
○ Train vines high - above cold air near ground
○ Have bare soil bet vines (vs cover crop) -> absorbs more heat during day and radiates heat at night
Hazards, Pests, Diseases
What are 3 management actions to reduce impact once frost happens?
- Water sprinklers
- Wind machines
- Heaters/smudge pots
Hazards, Pests, Diseases
How do sprinklers reduce impact of frost?
What is another term for sprinklers?
Considerations - adv/disadv
What type of frost is this the only solution for?
Other term - aspersion
How sprinklers work:
§ as water freezes around plant (going from liquid to solid), it releases latent heat; must be kept on until temps rise
§ Can be used as part of irrigation, or put out to deal with frost conditions
§ Cost - equipment and water; cheaper than wind machines or heaters
§ ONLY option for advective frost
Hazards, Pests, Diseases
How do wind machines reduce the impact of frost?
What conditions are necessary for them to be effective?
What are economic considerations?
§ 4-7m high fans pull warmer air from above down to ground, raising temp
§ Effective when there is inversion layer - warm zone of air 10m above ground +3-5°C
§ Cost effective when there is risk of damaging radiative frost every 5yrs (20% chance in any one yr); signif initial investment; can also use helicopters - very expensive but can be worth it in extreme sit
Hazards, Pests, Diseases
How do heaters/smudge pots/wax candles work?
What are economic and other considerations?
§ Oil or gas heaters and wax candles put in vineyard when risk of frost.
§ High labor cost, cost of fuel, low heating efficiency, contributes to air pollution
Hazards, Pests, Diseases
What is hail?
How does it impact vines?
What are the implications (early vs late season)?
What are management options?
○ Pellets of frozen rain
○ Damage and rip young shoots and leaves, ripening grapes can be damaged and allow bot and other diseases
○ Significant yield impacts in first and following seasons; also lower quality fruit due to vine shift focus back to re-growth (if hail in early spring)
○ If early in season, vine may be able to re-shoot from existing buds
○ Hail is generally unpredictable, but Burg and parts of Argentina susceptible
Management options: ○ Rockets with silver iodide fired into clouds to cause rain vs hail ○ Net the fruit zone in areas with regular hail - creates shading so only used in areas with high sunlight -> better in Argentina than Burg ○ Plant grapes in multiple areas since hail damage usually very localized ○ Crop insurance
Hazards, Pests, Diseases
What is sunburn?
What are its impacts?
What are management options?
○ Prolonged hot weather can cause grape sunburn -> since grape transpiration much less effective at temp regulation than leaf transpiration -> grapes get hot and get burnt
○ Higher risk if vines have water stress
○ Causes scars on skin of grapes -> can kill grapes
○ Negative impact on quality - browning of grape = bitter taste; inc risk of rot due to skin damage => need to be removed = reduced yields
Management options:
○ Vineyard design - row orientation and aspect reduce hot afternoon sun exposure - avoid e/w exposure in N hemi
so grapes on S side not exposed to sun all day
○ Canopy management - shade fruit zones in hot regions
○ Heatwave forecast - additional irrigation if allowed -> reduce water stress
○ Special agriculture sunscreen spray
○ Shade vines with net
Hazards, Pests, Diseases
What are considerations related to fire risk?
What are management options?
○ Some areas affected by climate change have higher fire risk - CA, Australia, Chile
○ Cover crops/mulches can provide fuel for fires; fire inhibited by bare soil
○ Vine damage/death and smoke taint are issues
Management options: ○ Install fire detectors and sprinklers ○ Install water tank ○ Employee training/action plan
Hazards, Pests, Diseases
What are impacts of smoke taint on vines and wines?
How does it work within the grape?
What are management options?
Impact and how work within grape:
* free guiacols are the chem element -> add plastic/smoky aromas -> impact increases after veraison
* smoke aroma compounds absorbed by grapes and bind with sugars -> form aroma-less precursors that only
become aromatic during ferm; can increase with aging as more precursors break down and become aromatic
Management options:
○ Test affected musts analytically and/or by micro-vinification (vinify small samples from vineyard) to assess extent
of problem
○ Grape handling may reduce impact of smoke taint - since smoke aroma pre-cursors present on inside of skin ->
hand harvest, lower ferm temps, gentle/whole bunch pressing, reduced maceration = reduced uptake of
negative compounds
○ Flash détente - destemmed grapes quickly heated (2min) to ~85-90°C and then rapidly cooled in vacuum;
○ Reverse osmosis - reduce but not remove smoke taint
○ Blend with unaffected wines
Hazards, Pests, Diseases
What are pests?
What are considerations for growers in addressing them?
Organisms that harm vine - competition for water/nutrients or attack vine/grapes
Considerations: ○ Seriousness of attack, cost of addressing relative to potential damage
Hazards, Pests, Diseases
What are 6 main types of pests?
Phylloxera
Nematodes
Grape moths
Spider mites
Birds
Mammals
Hazards, Pests, Diseases
What is Phylloxera?
When was it discovered?
How does it spread?
How does it cause harm?
○ Aphid-like insect feeds and lays eggs on roots of vines
○ Discovered in Europe in 1863 -> accidentally introduced from US via imported vines
○ Spread mainly via human transport - vines, soil, machinery; can also spread from crawling
○ Harms vines by damaging roots -> reduces uptake of nutrients and water; also makes roots vulnerable to attack by bacteria and fungi = weakening of vine reducing growth and yield then death
Hazards, Pests, Diseases
What symptoms do phylloxera-infected vineyards show?
○ Die of drought in patches that inc yr over yr
○ Vine roots covered with insects surrounded by yellow eggs
○ Swelling on older roots
○ Pale green leaf galls on underside of leaves
○ Slow, stunted shoot growth and leaf yellowing appears in ~3 yrs; plant dies around 5yrs
Hazards, Pests, Diseases
What are management options for Phylloxera?
Plant on sandy soil - immune to phylloxera
Use American root stock hybrids
Hazards, Pests, Diseases
What was the initial primary approach to managing Phylloxera?
How does it work?
What was a side effect and resulting shift in approach?
What was a secondary issue related to using American rootstock for Phylloxera?
What is the long term solution?
initial approach
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
Hazards, Pests, Diseases
What are nematodes, what kind most common?
How does it spread?
How does it cause harm/symptoms?
What are management options?
○ 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)
Hazards, Pests, Diseases
What are Grape Moths, what kind most common?
How does it spread?
How does it cause harm/symptoms?
What are management options?
○ 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
Hazards, Pests, Diseases
What are spider mites, what kind most common?
How does it spread?
How does it cause harm/symptoms?
What are management options?
○ 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
Hazards, Pests, Diseases
What threat do birds pose and where?
What damage do they do?
What are management options?
○ 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
Hazards, Pests, Diseases
What are common mammal pests?
What damage do they do?
What are management options?
○ 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
Hazards, Pests, Diseases
What are the 3 main categories of diseases?
Fungal
Viral
Bacterial
Hazards, Pests, Diseases
What are the 2 broad categories and 6 specific types of fungal disease?
Attack green parts/bunches:
Powdery mildew
Downy mildew
Grey rot
Attack woody parts:
Eutypa Dieback
Phomopsis Cane and Leaf Spot
ESCA
Hazards, Pests, Diseases
What is powdery mildew, what is another common name for it?
What is it’s history?
Which varieties susceptible?
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
Hazards, Pests, Diseases
How does Powdery mildew affect vines?
What harm/symptoms?
What implications?
What management options?
○ 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
Hazards, Pests, Diseases
What is downy mildew - name of mold
Where does it live on vine?
What is it’s history?
○ 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
Hazards, Pests, Diseases
How does downy mildew affect vines?
What symptoms?
What implications?
What management options?
○ 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
Hazards, Pests, Diseases
What is grey rot, name of fungus?
How does it affect vines?
What symptoms?
What implications?
What varieties at risk?
What management options?
○ 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
Hazards, Pests, Diseases
What is Eutypa Dieback, alt name?
How does it affect vines?
What symptoms?
What implications?
What varieties at risk and where?
What management options?
○ 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
Hazards, Pests, Diseases
What is Phomopsis Cane and Leaf Spot?
How does it affect vines?
What symptoms?
What implications?
What varieties at risk and where?
What management options?
○ 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
Hazards, Pests, Diseases
What is ESCA?
How does it affect vines?
What symptoms?
What implications?
What varieties at risk and where?
What management options?
○ 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
Hazards, Pests, Diseases
What are the 2 main bacterial diseases?
Pierce’s disease
Grapevine yellows
Hazards, Pests, Diseases
What is Pierce’s disease and where originate?
How does it affect vines/how spread?
What symptoms?
What implications?
What varieties at risk and where?
What management options?
○ 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
Hazards, Pests, Diseases
What Grapevine Yellows?
How does it affect vines/how spread?
What symptoms?
What implications?
What varieties at risk and where?
What management options?
○ 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
Hazards, Pests, Diseases
What are the 2 main viral diseases?
Fanleaf virus
Leafroll virus
Hazards, Pests, Diseases
What is Fanleaf virus?
How does it affect vines?
How spread?
What symptoms?
What implications?
What varieties at risk and where?
What management options?
○ 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
Hazards, Pests, Diseases
What is Leafroll virus?
How does it affect vines?
How spread?
What symptoms?
What implications?
What varieties at risk and where?
What management options?
○ 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
