Grapevine pest/table grapes - Knowledgebase Question

Vacaville, CA
Question by sandylee5
August 2, 2007
I have six vines of over 20 yrs in age on a wood arbor, that, this year produced a good crop of table grapes---they are mostly of the Flame/seedless variety but I also have one of Black Monucca and one of Thompson Seedless. We were out of town when the really hot weather hit near July 4, plus the leaf hopper population just went crazy this year, most of the leaf cover is destroyed, leaves are 90% or more skeletonized. I've been watering the vines slowly by hand sprinkler, hopeing to stimulate new leaf growth, should I also spray and what should I use that will not affect the developing and ripening grapes?----Any advice would be appreciated-------Sandy Davidowski

Answer from NGA
August 2, 2007


Although leafhoppers infest most vineyards in California, they may not require chemical treatment because vines can tolerate fairly high populations without harm, and predators and parasites may be able to maintain leafhopper populations below tolerance levels. It takes some time for the leafhopper population to become high enough to attract predatory insects. It sounds as though your grapevines have reached that threshold.

Unfortunately, there are not many insecticides registered for homeowner use. Insecticidal soaps will work, but applied this late in the year will spot the bloom on the grape skins. It isn't harmful, but doesn't look very attractive.

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