Invertebrates and Plant Diseases—Damage to Fruit at Harvest

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.

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.