D8: Hazards, Pests and Diseases Flashcards
Name 9 hazards which can have an impact on grape growing
- drought
- excess water
- untimely rainfall
- freeze
- frosts
- hail
- sunburn
- fire
- smoke taint
DROUGHT
what is the minimum amount of water a vine needs in a) cool climate and b) warm climates?
Cool: 500mm
Warm: at least 750mm
DROUGHT
what happens to the vine with lack of water?
- stomata closes in order to limit water loss
- this reduces photosynthesis which then stops the plant growing. This impacts the size of the grapes and ripening also slows
- causes unripe grape
- if has lack of water for too long, vines lose their leaves and die
DROUGHT
What can happen to vineyards where water is scarce and irrigation is limited? Give examples
- can lose whole vineyards
EXAMPLE: Olifants River in South Africa
DROUGHT
What are the management options for drought?
- irrigation (where permitted)
- drought resistant rootstock (e.g. 110R or 140R)
- drought tolerant grapes (e.g. garnarcha)
Name two drought resistant rootstock
100R and 140R
Name a drought tolerant grape variety
Garnacha
EXCESS WATER
Excessive water can lead to…
1) excessive vegetative growth
- too shady, too much competition for nutrients
- leads to less ripeness
2) fungal disease due to high humidity
3) waterlogged soils
EXCESS WATER
What is the impact of waterlogged soils?
- reduces oxygen in soil
- slows growth
- eventually kills the vine
- causes compaction in soil so difficult to work and can cause uncontrolled water run off
EXCESS WATER
What are the management options for Excess Water?
- slope planting
- free draining soils
- construction of drainage systems
UNTIMELY RAINFALL
What two conditions can this cause during pollination and fruit set?
- coulure
- millerandage
- reduces crop size and lowers quality
UNTIMELY RAINFALL
What else does this impact?
- rate and ripening of fruit as you want some water deficiency before veraison
UNTIMELY RAINFALL
What can happen if there is rainfall before harvest
- swollen and splitting grapes
- rot
- also makes machine harvesting difficult
UNTIMELY RAINFALL
What are the management options?
- think about site choice, soil and drainage adequacy
- monitoring weather around the harvest
FREEZE
At what temperature can a vine be killed or damaged?
- below -20 degrees/-4 Fahrenheit
FREEZE
What part of the vine is most at risk?
- graft
- then canes/cordons
FREEZE
What three places are most at risk
- Canada
- Washington State
- China
FREEZE
What are the management options?
- site selection
- hillsides are warmer than plains
- near a body of water
- plant where deep snow settles as protects vine
- varieties
- resilient (cab franc, riesling)
- winter hardy (Concord - tolerant up to -35 degrees or other mongolian varieties)
- protection
- hilling up/building soil around vine graft
- burying vines (often seen in China)
- prune vines to have several trunks so can replace any that are killed
FROSTS
What happens when freeze occurs?
- when cold air below zero degrees collects at ground level, it freezes water in vines growing buds and shoots
- will kills any newly burst buds or young shoots which have a high water content
- impacts yield and quality
FROSTS
Where is the risk highest for frost?
- areas with cool and warm climates
- if buds are killed, secondary buds take much longer to grow and establish
FROSTS
What are the two different types of frost which can occur?
ADVECTIVE FROSTS
- large volumes of cold air moving in from very cold areas
RADIATIVE FROSTS
- result of heat being lost on still, cool nights.
- allows for layer of freezing, cold air to develop just above the surface of soil.
- collects in valley bottoms
FROSTS
What are the management options?
- site selection (avoiding frost pockets)
- delay pruning so as to delay budburst
- chose late budding varieties
- train vines high
- have bare soil between vines so as to radiate heat at night
FROSTS
What can you do when frost threatens?
- water sprinklers: as water freezes around the plant, it releases latent heat and protects the plant
- wind machines: pulls warm air from above down to the ground level
- needs INVERSION LAYER: warm air zone 10m above ground
- expensive but main cost is upfront
- oil or propane heathers: placed around vineyards and lit when risk of frost
- costly, labour intensive and not environmentally friendly
HAIL
What damage can hail do to a vineyard?
- damage and rip young shoots and leaves
- damage grapes and become entry points for botrytis and disease
- reduce yield at the time and in future seasons
HAIL
What are the management options for hail?
- rockets fired at thunderclouds (so it falls as rain and not as hail)
- net fruit zone (can only do in high sunlight areas as it causes shading)
- have plots in different areas
- crop insurance
SUNBURN
- what issues does sunburn cause?
- limits grape transpiration so grapes reach higher temperatures than the leaves and become burnt
- higher risk if vine is already water stressed
- can cause scars on skins and leads to death of the grape
- negatively impacts grape quality (browning, bitter taste, risk of rot)
- need to ensure sunburnt grapes are removed at sorting which decreases yield
SUNBURN
What are the management options?
- row orientation and aspect so can manage sun exposure
- canopy management (so can try and shade fruit)
- additional irrigation in a heatwave
- agricultural sunscreen can be applied or shade can be provided with cloth or netting
FIRE
Where are the areas with the highest incidences of fire?
- california
- australia
- chile
FIRE
What are the worst conditions/places for areas with high fire risk?
- near woods
- near pastures
- crops using mulch
** all are fire risks
FIRE
What are the management options?
- installing fire detectors and sprinklers
- water tanks
- employee training
SMOKE TAINT
What is the impact of smoke taint?
- can cause ‘smoky’ or ‘plastic’ aromas in final wine
- impact increases from veraison onwards
- aroma compounds in smoke can be absorbed by grapes
- once in grapes, compounds bind with sugars and form aroma-less precursors
- these only become aromatic during fermentation and develop/increase with ageing
SMOKE TAINT
What are the management options?
- can test must analytically by MICRO-VINIFICATIONS to see if there is a problem
- hand harvesting, gentle or whole-bunch pressing, lower fermenting temperatures and reduce maceration can reduce uptake of compounds
- flash detente and reverse osmosis can help but won’t remove taint completely
What impact can PESTS have?
- compete for water or nutrients
- can directly attack the vine and/or grapes so affect yield and quality
- some pests and diseases are result of being transferred to territory with no previous resistance e.g phylloxera in Europe
PHYLLOXERA
what does Phylloxera do?
- insect feeds on and lays eggs on roots of grape vines
- weakens roots, causing swelling and cracks which leads to rot
- spreads through crawling or flying - usually via humans on roots, soil, equipment, irrigation systems
PHYLLOXERA
What are the symptoms of phylloxera?
- vines die of drought and patches increase year on year
- roots are covered with insects surrounded by yellow eggs
- swellings on older roots
- pale green leaf galls on under-surface of leaves
- slow, stunted shoot growth and leaf yellowing appears around 3 years, and then plant dies after about 5 years
PHYLLOXERA
When was Phylloxera introduced/identified?
- 1863
- destroyed 2/3rds vineyards in late 19th Century
PHYLLOXERA
What are the management options for Phylloxera?
- use of american rootstocks which form seals around the wounds which prevent invasion by bacteria or fungi. Need to be paired with European vines as rootstocks don’t give pleasant wine!
- 3 american rootstock varieties:
- v. berlandieri
- v. riparia
- v. rupestris
PHYLLOXERA
What are the issues associated with using american rootstocks?
- issues on calcerous soils. Can cause chlorosis
- have created rootstock hybrids between american species so as to balance protection and resistance to lime in soil
- american rootstocks which were developed could deal with a number of problems (phylloxera, nematodes, extreme soil pH, water stress, salinity) as well as can control vine vigour
- today a vineyard would get tailored advice on choice of rootstock and grape variety to match to their vineyard
NEMATODES
What are nematodes?
- tiny worms found in soils
NEMATODES
What issues do nematodes cause?
- feed off vine roots, reducing yield and vigour
- cause slow decline of vine
- can transmit viral diseases (e.g. fanleaf virus)
NEMATODES
What are the two most common nematodes?
- root-knot nematode
- daggar nematode
- either found in the soil
or - spread by unclean nursery stock, irrigation or vehicles
- can never be eliminated - only managed
NEMATODES
What are the management options for nematodes?
- need to take soil samples to lab to determine number and type
- can leave soil to fallow for number of years (very expensive as no crop!)
- fumigate soils - have to use chemicals which are mostly banned now
- plough in cover crop of mustard plant which contains compounds which work as BIOFUMIGANTS, killing the nematodes
- best solution: nematode resistant rootstocks
GRAPE MOTHS
What issues do grape moths cause?
- can attack at different times
- flowers in spring
- grapes later on
- create wounds which cause more issues later one and can lose a lot of crop
GRAPE MOTHS
what are the three most common grape moths?
- light brown apple moth (australia)
- european grapevine moth (southern europe)
- grape berry moth (central and eastern north america)
GRAPE MOTHS
What are the management options for grape moths
- insecticides
- biological controls
* bacterium BACILLUS THURINGIENSIS
* produces a substance toxic to moths
* sexual confusion (using pheremone capsules)
* natural predators (parasitic wasps, green lacewings, some spiders)
SPIDER MITES
What issues to spider mites cause?
- most detrimental mite to vines
- differ from region to region
- feed on surface cells of leaves which leads to: discolouration,
reduction in photosynthesis,
delays in ripening,
reduces yields
SPIDER MITES
What conditions to spider mites thrive in?
- dusty conditions
- especially damaging when vine is water stressed
SPIDER MITES
Name 3 types of spider mites
- pacific spider mite (california)
- red spider mite (europe)
- two forms of yellow spider mite (europe)
SPIDER MITES
What are the management options?
- create an inhospitable environment
- sprinklers
- cover crops etc
- encourage predatory mites that feed on spider mites
- general pesticides
BIRDS
What damage can birds cause?
- can destroy an entire crop as ripening occurs
- this is especially prevalent if vineyard is isolated and is the only source of food
- bird damage allows bacteria and fungi to enter bunches which causes rot
- starlings are biggest risk
BIRDS
What are the management options?
- netting (very expensive!) They use this in Mornington Peninsula
- bird scarers, noises etc. Need to rotate often so don’t become used to them
- falcons used to deter birds
MAMMALS
What problems do mammals cause?
- eats shoots, grapes, leaves
- break grape skins, which make them vulnerable to rot
- damage trellising
- lowers yield
- lowers quality
- costs to repair damage
MAMMALS
What do the pests include?
- deer
- rabbit
- kangaroos
- racoons
- wild boar
- baboons
MAMMALS
What are the management options?
- fencing - needs to be high enough and sunk deep enough to stop animals jumping or burrowing
Name the 6 pests which can cause issues to grape growing
- phylloxera
- nematodes
- spider mites
- grape moths
- birds
- mammals
Name the 6 fungal diseases which cause issues to grape growing
- powdery mildew
- downy mildew
- grey rot
- eutypa dieback
- phomopsis cane and leaf spot
POWDERY MILDEW
What fungus causes powdery mildew?
ERYSIPHE NECATOR
- aka OIDIUM TUCKERI
- its grapevine specific but american species are less vulnerable than v. vinifera
- most widespread vine disease in the world
POWDERY MILDEW
What two varieties are most prone to the disease and which two are less prone?
- PRONE: Cab and Chardonnay
- LESS PRONE: Riesling and Pinot Noir
POWDERY MILDEW
How does it attack vines?
- overwinters in buds and on canes
- attacks young green parts of vine - starts dull grey and then becomes black
- patches damage young shoots, inflorescences and grapes
- reduces yields
- can cause grapes to split during veraison and become targets for other infections
POWDERY MILDEW
What is the optimum temperature for growth for powdery mildew?
- 25 degrees
- thrives in the shade
- doesn’t require high humidity and can spread in dry conditions
POWDERY MILDEW
What are the management options?
- OPEN CANOPIES: reduce shade and leaf density
- SULFUR: helps prevent and treat. Spray from budburst to veraison. Need to spray early to prevent rather than contain
- SYSTEMIC FUNGICIDES: penetrate green tissue, not washed off by rain. Can become resistant so limit applications
DOWNY MILDEW
What is it caused by?
- PERONOSPORA: water mould that lives within vine tissue. Common in most wine regions
- attacks green parts of plants, especially young leaves and flowers. Reduces yield by defoliating vines
DOWNY MILDEW
What does it need to spread?
- rainfall
- warm temps of approx 20 degrees
DOWNY MILDEW
What are the symptoms?
- yellow, circular ‘oil spots’
- white, downy fungal growth on underside of leaves
DOWNY MILDEW
What are the management options?
- sprays of copper salts e.g. BORDEAUX BLEND - combo of copper sulfate and lime.
* protection doesn’t last long - only until 20mm rain has fallen - fungicides - applied from month after budburst to veraison
- good drainage and an open canopy
GREY ROT
What is it more commonly known as?
- botrytis cinerea
GREY ROT
What issues does it cause?
- loss of yield and drop in quality of wine
- grapes need to be selected out at harvest
- grapes are very vulnerable if there is a point of entry and whole bunches can be attacked
- if flowers are affected, fungus can stay dormant until after veraison
GREY ROT
What grapes are most at risk?
- grapes with tight bunches or thin skins are most at risk
- Sauv Blanc
- Semillon
- Pinot Noir
GREY ROT
When do spores become active?
- in periods of rainfall and high humidity
GREY ROT
What are the management options?
- choosing grapes with thick skins and higher resistance
- protecting grapes from pests
- keeping the canopy open, removing leaves around bunches
- fungicides (not copper or sulfur) - apply when flowering nearly complete, end of grape formation, bunch closure and veraison. Not very effective as fungus develops resistance
- antagonistic bacteria - BACILLUS SUBTILIS - can also use other forms of biological controls
EUTYPA DIEBACK
What is it and what does it cause?
- AKA ‘dead arm
- fungal trunk disease leading to rotten wood in vines
- reduces yields
- kills vines over 10 year period if not tackled
EUTYPA DIEBACK
How does it spread?
- spores spread by wind over long distances
- occurs through pruning wounds in moderate temperatures - especially during rain
- effects are evident in spring as short young shoots come through and yellow leaves
EUTYPA DIEBACK
What grape varieties are particularly susceptible?
- grenache
- cab
- sauvignon blanc
EUTYPA DIEBACK
Which regions are particularly susceptible?
- South Australia
- SW france
- California
EUTYPA DIEBACK
What are the management options?
- v difficult to control
- pruning late and applying fungicide to the pruning wounds
- cut back affected trunks 5-10cm beyond visible symptoms
- burn dead wood to avoid spreading
- biological controls - BACILLUS SUBTILIS
- if badly affected, retrain from sucker (shoot that grows from base of the vine) which would take 2 years, or remove the vine and replant
PHOMOPSIS CANE AND LEAF SPOT
What is it and when does it occur?
- fungal disease causing reduction in crops
- prevalent where cool and wet springs are followed by humidity and moderate temperatures
PHOMOPSIS CANE AND LEAF SPOT
- what does it present as?
- canes whiten and break off easily
- shoots growing from canes develop brown cracks at bases
- leaves can also be affected
PHOMOPSIS CANE AND LEAF SPOT
what grapes are most susceptible?
- grenache
- cab sauv is less affected
PHOMOPSIS CANE AND LEAF SPOT
What are the management options?
- fungicide applied three weeks after budburst and every 2 weeks if wet conditions continue
- diseased wood removed and burned
- prune early or late, and not when its raining
ESCA
What is it?
- complex fungal disease caused by groups of organisms prevalent in warmer/drier climates (e.g. S Europe, California)
- enters pruning wounds
- reduces yield of plant and causes it to die
ESCA
How does it present?
- tiger striping of leaves
- spotting inside wood
ESCA
What are the management options?
- all about disease prevention
- disease-free stock
- less detrimental pruning
- not pruning in the rain
- removing prunings from vineyard
- disinfecting pruning wounds
What are other possible fungal diseases which need to be considered?
- black rot
- black-foot disease
- bot canker
- anthracnose
What two bacterial diseases need to be considered?
- Pierce’s disease
- grapevine yellows
PIERCE’S DISEASE
What is it?
- kills vines quickly
- believed to have american origins as present in California
- bacterium lives in sap channels of vines causing them to clog, shrivel and drop their leaves
- vines typically die between 1 and 5 years
PIERCE’S DISEASE
How is it spread?
- by a sharpshooter insect (vector)
PIERCE’S DISEASE
What are the management options?
- no chemical control so need to test vines in labs
- need to reduce number of vectors by:
- removing vines close to rivers as riverbanks harbour vectors
- chemical insecticides
- wasps which feed on eggs of sharpshooters
- strict quarantine on movement of plants
- development of Pierce’s Disease resistant vines
GRAPEVINE YELLOWS
What is it?
- group of diseases cause by type of bacteria
- serious threat as no treatment
GRAPEVINE YELLOWS
How is it spread?
- spread by vectors including leafhoppers and by nurseries selling diseased, untreated stock
GRAPEVINE YELLOWS
What is it commonly known as in Europe?
Flavescence Doree
GRAPEVINE YELLOWS
Where else is it commonly found?
- germany
- france
- s Europe
- NY State
- Australia
GRAPEVINE YELLOWS
What are the symptoms?
- delayed budburst
- drooping posture (new shoots fail to lignify)
- canopy turning yellow (white varieties) or red (black varieties)
- vine either dies or can recover after an attack
GRAPEVINE YELLOWS
What are the most vulnerable varieties
- Chardonnay
- Riesling
GRAPEVINE YELLOWS
What are the management options?
- no control
- need to control the vector e.g. control the leafhopper with insecticides, removing cover crops etc
- Nurseries need to bathe pruning wound in hot water to kill disease
Name two other bacterial diseases
- bacterial blight
- crown gall
Name two viruses which cause issues in the vineyard
- fanleaf virus
- leafroll virus
FANLEAF VIRUS
What is it?
- longstanding group of diseases - found around the world
FANLEAF VIRUS
What happens to the vine?
- early shoot growth stunted
- canes distorted
- pale leaves which are malformed and look like fans
- can lose most of the crop in some cases
FANLEAF VIRUS
How is it spread?
mainly spread with DAGGER NEMATODES
- historically spread on grafted vines using infected plant material
FANLEAF VIRUS
What are the management options?
- no cure - infected vine needs to eventually be removed
- before replanting, need to test the soil for presence of dagger nematodes
- should only use virus-tested clean planting materials
LEAFROLL VIRUS
What is it?
- group of viral diseases widely present around the world
LEAFROLL VIRUS
How is it spread?
- spread by grafting
- spread by MEALY BUGS (SA, Mediterranean, Argentina, California)
LEAFROLL VIRUS
What does it do?
- doesn’t kill but does reduce yield by half
- affects quality of grapes
- slows down growth of roots and shoots
* can take fruit additional weeks to ripen and have more acidity, less colour and lower sugar levels - affect carb stores in vines
LEAFROLL VIRUS
When does it usually occur and how does it present?
- in autumn
- leaves change colour to red (black grapes) or yellow (white grapes)
- have to lab test vines as can carry virus without showing symptoms
LEAFROLL VIRUS
What are the management options?
- no cure
- only solution is to remove unproductive vines and replant with virus free stock
- nurseries need to screen for infection
- open canopies to reduce humid environment
