Look for the following types of damage in your
harvest sample. Note
the presence of vinegar flies as an indicator of bunch rot diseases. Names
link to more information on identification and management.
Click on photos to enlarge
| Diseases and disorders |
Botrytis bunch rot
Identification tip: A berry infected with Botrytis bunch rot
turns brown, splits, and leaks. As the disease progresses the infection
spreads to other berries.
|
Measles
Identification tip: On berries, small, round, dark spots,
each bordered by a brown-purple ring, may occur.
|
Summer bunch rot
Identification
tip: Examine clusters for masses of black, brown, or green spores
that develop on the surface of infected berries.
|
Non-Botrytis slip skin of ‘Redglobe’ grapes
Identification
tip: Look for watery discoloration, presence of hairline cracks on
berry surface and general berry breakdown.
|
| Insects |
Western grapeleaf skeletonizer
Identification
tip: Sunburned fruit resulting in the loss of quality can be a result
of defoliation by western grape leaf skeletonizer.
|
Omnivorous leafroller
Identification tip: Look for rotting and raisining (drying) of Thompson
seedless grapes follows chewing damage by omnivorous leafroller larvae.
|
Grape mealybug
Identification tip: Examine clusters for cottony egg sacs, larvae,
adults, and honeydew.
|
Vine mealybug
Identification tip: Honeydew and white wax on grapevines are often
and indication of a vine mealybug infestation
|
Thrips
Identification tip: Halo spots appear as small scars around
sites where thrips punctured the grape to lay eggs.
|
Thrips
Identification tip:
Thrips feeding causes a starfish pattern of scarring on berries.
|
Vinegar fly adult
Identification
tip: Adults (also called fruit flies) are small, yellowish flies
that are commonly attracted to fermenting fruit of all kinds. They
indicate the presence of bunch rot disease.
|
