Will be in the exam

Question 1

Eutypa dieback

Answer 1

widespread in cooler, wetter districts of Australia (rainfall > 350 mm) rare in vines < 8-10 years old

Question 2

Botryosphaeria dieback (Bot canker)

Answer 2

Symptoms

• Dying arms, canker and wood stained as in Eutypa dieback but distinctive foliar symptoms absent
• May cause bunch rot, pycnidia on berries

Question 3

Eutypa dieback vs botryosphaeracancker

Answer 3

Question 4

• Recognise and describe important diseases of grapevine based on symptoms and signs

Question 5

Powdery mildew

When, where and how to access ?

Answer 5

Example: early-season powdery mildew

Biology of pathogen and disease

• primary infection
• flag shoots in canopy
• independent of rain-ascospores from bark –2-3 mm rain, >10˚C, symptoms/signs 1-2 weeks later

Conducive weather conditions

• mild overcast weather, dense canopy, RH 85%
• in-canopy temperature 23-30˚C

Vine/vineyard characteristics

• susceptibility of cultivar/variety
• sheltered areas, canopy retains humidity

Role of“hot-spots”

What is a “hot - spot”

disease begins early and is severe

• susceptible variety
• disease severe in previous season(s)

→ chasmothecia on bark, infected buds [primary inoculum] and/or downwind of inoculum source

• sheltered area of vineyard
• dense canopy

→ high RH, poor penetration of light and fungicides

“hot - spot”: Action?

• Tag and target for control
• Monitor disease progression

Monitoring for powdery mildew:

• Begin in disease - prone areas or hot - spots
• Examine 200 vines at random across patch
• Calculate incidence
• Repeat at 2 - weekly intervals, guide management
• Close to harvest – assess bunches (severity)

Question 6

Explain –

biology of the pathogen

influence of environment on pathogen and disease

Question 7

poweder mildew

Answer 7

May be severe when weather mild and overcas

Symptoms and diagnosis

Leaves:

abaxial infection; yellowish blotches ( adaxial ) and

grey/white powdery layer (a baxial)

adaxial infection: whitish growth, metallic sheen

white/grey and powdery as fungus sporulates

Shoots:

white - ash grey patches, stunting, may die, grey patches on shoot stem

red - brown patches on mature canes

Bunches:

ash - grey growth on berrie and rachi berries may split as epidermal growth i

‘musty’ smell late in season