Disease Summary Cards Flashcards
Powdery Mildew
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Oidium tuckeri
Young green parts
Overwinter - canes and buds
Humidity not needed/25°C
Gray/black patches
Damage young shoots, infl, grapes split ver
Open canopy
Sulphur - spray early BB - better to prevent
Syst fungicide penetrate green parts
Chard, Cab
Downy Mildew
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Peronispora fungus
Defoliation causes significant yield loss; attacks young leaves and flowers; grapes can split at ver
Lives in vine tissue
Yellow oil spots on leaves, then white downy growth on underside of leaves
Reduced yield - less PHS
Humid/rainy conditions and warm temps 20°C
Bordeaux mixture spray - copper sulfate + lime - effective until 20mm rain
Open canopy
Grey Rot
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Botrytis cinerea - spores live in vy
Humid, rainy conditions
Attacks thin skinned grapes - PN
Attacks via skin damage - leads to whole bunches infected
Significant yield and quality impact - less color, body, flavor
Plant thick skin var
Open canopy
Select out damaged fruit/bunches
Fungicide - not sulfur or copper
Bio control - bacillus subtilis
Thin skinned affected - PN, Sem,SB
Eutypa Dieback
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Deadarm
Attack via pruning wounds
spread by wind - can infect whole vy
Stunted shoots, yellow leaves; rots wood
Cond - mild temps and esp risk during rain
Reduce yield , kills within 10yrs
Cut back 5-10cm past infected wood, burn
Fung on pruning wounds, prune later in spring
Bio control - bacillus subtilis
Var - Gren, CS, SB
Phomopsis Cane and Leaf Spot
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Attacks canes and leaves = signif reduced yield
Canes whiten and crack; shoots on them have brown cracks
Cool wet spring followed by mod temps and humidity
Fungicide - after BB and every 2 weeks during wet cond
remove pruning asap and burn
Open canopy
Grenache
ESCA
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Complex fungal disease
Attack via pruning wounds
Warm/dry conditions
Tiger striping of leaves, spots inside wood
Reduces yield, kills within a few yrs
No chem controls - focus on prevention
Disease free stock, remove and burn pruning asap
disinfect pruning wounds
Reseach on bio control- bacillus subtilis
Pierce’s Disease
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Bacterial disease
Glassy-winged sharpshooter
Clogs sap channels -
Grape shriveling, drops leaves, kills vines 1-5 yrs - yield and quality
No chem control - lab testing
Quarantine
Control - reduce vector - Insecticide, remove vines near river banks, nat pred - wasps feed on eggs
Grapevine Yellows
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
group of bacterial diseases - sometimes kills, signif reduce yield and qual
Vector - leafhoppers and diseased stock from nurseries
Can live in range of plants incl cover crops
Droopy posture, shoots dont lignify, yellow/red canopy
Delayed BB = delay ripen = qual impact - low sugar/high acid
No control vs bacteria
Control vector - insecticide, remove host plants
Bathe pruning wood in hot water
Chard/Riesling
Fanleaf Virus
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Viral disease - grafting and dagger nematodes
Stunted early shoot growth and distort canes
Leaves pale and fan shaped = less phs
Effect minimal to lose whole crop
No cure - need to remove and replace vines = cost
Before replant, test soil for nematodes, source clean plant mat
Leafroll virus
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Group of viral diseases - mealy bugs and grafting
Slows root and shoot growth
Leaves roll down in fall, color change of canopy
Vine stores less carbs - impact overall health of vine
Doesn’t kill but can reduce yield 50%; surviving grapes - higher acid/less color and sugar
Need lab test
No cure - remove/replant; nurseries screen
Vector control - open canopy mealy bugs prefer humidity
Nat pred - lady bugs and lacewings
Coulure
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Fruit set fails for high proportion of flowers - unsuccsessful ovule fertilization and no grape forms
Hens and chicks
Due to carb imbalance - low phs, cold/cloudy or hot/high water stress, too much vigor divert carb from infl
- too much fert, vigorous rootstock
Gren, CS, Mer, Malb
Millerandage
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Hens and chicks
Pollination disrupted at flowering resulting in high prop of smaller, seedless grapes
Reduces vol of wine due to fewer fully ripe grape, small grapes green high acid, bitter
Cool temp and rain during flowering; insufficient nutrients
Chard, mer
Chlorosis
- Cause
- Conditions
- Symptoms
-Vine impact
- Effect
-Mgt Options
- Key var impacted
Insufficient iron turns leaves yellow - reduce phs
Cond - high soil pH, too much water prevent iron uptake
Yellows leaves - stops PHS and ripening - reduces yield and quality
