Symptoms: Adult Beetles come into vineyards when new shoots are about 1 foot (30 cm) long. Eggs are laid inside shoots about 6 inches (15 cm) from tips. Larvae tunnel inside shoots, destroying them.
Cure: Inspect canes and cut off about 4 inches (10 cm) below girdling area.
GRAPE BERRY MOTHS
Symptoms: Moth larvae feed inside fruits. Grapes are often webbed together. Wormy fruits result.
Cure: Set out pheromone traps to know when to spray with organic Bacillus thuringiensis var. kurstaki.
LEAF ROLLERS; LEFT TIERS
Symptoms: Larvae of moths feed on foliage of new shoots, chewing them badly. They may also feed on fruits.
Cure: Spray with organic neem in early summer. Repeat 2 weeks later.
ROSE CHAFERS, JAPANESE BEETLES and ORIENTAL BEETLES
Symptoms: Adult beetles feed heavily on foliage during day, causing severe skeletonizing of leaves.
Cure: Handpick adult beetles. Spray vines with organic neem to deter beetles from feeding. Place pheromone traps downwind away from the vines.
Symptoms: Fungus attacks leaves in early summer and later appears on fruits that are half grown. Entire grape shrivels to dry, black, raisinlike fruit.
Cure: Infection occurs during bloom period. Apply copper spray just before bloom, after bloom and every 10 to 14 days thereafter up to early fall. Remove mummified fruit and destroy.
Symptoms: Fungus, one of most destructive of all grape diseases, first attacks leaves and canes; later it infects young shoots. Dead arm phase results from infection through wounds caused by pruning or winterkill.
Cure: Remove infected vine at ground level during winter pruning. Spray with Bordeaux mixture when new shoots are about 1.2 inches (3 cm) long and again when they are 4.7 inches (12 cm) long.
Symptoms: First appears as small yellow spots on top of leaves. Later, downy white mats appear on lower surfaces. Complete defoliation may occur. Grapes are attacked, harden and turn off-color.
Cure: Same program as for black rot (above).
Symptoms: Mildew occurs on foliage in early summer and fall, producing white powdery growth on leaves and fruits.
Cure: Organic sulfur sprays should be applied as needed.