Control of Two Erythroneura Leafhoppers in Wine Grapes, 2016

The objective of this study was to evaluate the efficacy of both convential and organic insecticides in controlling VCL, which is a newly introduced pest of grapes in Northern California. Nine treatments were evaluated of control of a mixed population of VCL and WGL. Each treatment was replicated four times in an RCB design. Each replicate was four vines long. The study was conducted on mature ‘Sauvignon Blanc’ vines, near Kelseyville, CA. The vineyard was planted on 9-ft row × 7-ft vine spacing. Treatments were applied with a hand-held orchard sprayer operating at 200 psi with a finished spray volume of 150 gal/acre. Treatments were applied on 10 Jun. Treatments were evaluated by counting all second to fifth instar nymphs on two leaves from the center two vines in each replicate on 9 Jun (preapplication) and at 3, 7, and 14 DAT. Leafhopper data were analyzed using ANOVA and means were separated with Fisher’s protected LSD (P < 0.05) (Table 1).

There were moderate VCL and WGL populations in the preapplication through 7 DAT evaluations in the untreated check. The populations then decreased at 14 DAT. There was no significant difference in the mean number of VCL and WGL during preapplication and at 14 DAT. In the season totals, all materials provided significant control of both VCL and WGL when compared with the untreated check. Few or no VCL and WGL were observed in the Sivanto, Admire Pro, and PyGanic treatments, and these treatments had significantly lower VCL nymphs than Grandevo and the low rate of Beleaf and significantly lower WGL nymphs than Grandevo. No phytotoxicity was observed with any of the treatments.

This research was supported by industry gift.