Grape vine infection
I have 15 year old grapevine that flowers and produces bunches of green grapes; however, before they ripe, a grey or black coating spreads on the fruits, stems etc and they dry up. The plant survives but I was not successful in getting one edible grapes so far. I have sprayed "Fruit tree spray" in earlier years but not systematically. The plant has leaves but some leaves have holes in them. Please tell me what fungicide or any thing else I can spray this season. Thanks
Baltimore County Maryland
Hi- the holes in the leaves were very possibly caused by the larva of the grape flea beetle. The adults that preceded the larva feed on buds, so are considered a bigger problem than larval feeding on leaves. Typically, no control is recommended for these larvae.
The fruit rot is a common fungal disease called black rot. Fungicide sprays must begin when shoots first elongate in spring. Immunox (active ingredient is myclobutanil) is the most effective fungicide available to backyard gardeners. Clean up all infected fruit on the ground and on the vines to reduce the inoculum that will overwinter.
Spray recommendations for backyard fruit growers (section 3-18 and 3-19):