Conventional pesticides are highly effective in combating a new vineyard pest that has already worked its way south as far as Hopland. But for organic growers, it can pose a much bigger problem.
Two summers ago, when Lucia Varela, the North coast integrated pest management advisor for the UC Cooperative Extension, was called in to a Mendocino vineyard full of tiny insects that appeared immune to the usual pest control measures, she knew immediately that they were Virginia Creeper leafhoppers. One way to identify them, she explains, is through the patterns they create when laying their eggs.
While pesticides are effective in controlling the leafhoppers, Varela says a small parasitic wasp can also do the job, without chemicals.