Control of Vine Mealybug in Wine Grapes, 2016

This study was designed to evaluate the efficacy of Silvanto (flupyradifurone) and Assail (acetamiprid) in a season long VMB control program. The trial was conducted in a ‘Pinot Grigio’ vineyard, near Stockton, CA. Nine treatments were replicated four times in an RCB design. Each replicate was four or more vines long. The orchard was planted on 10-ft row by 6-ft vine spacing. Treatments were applied with a hand-held sprayer operating with a finished delayed dormant spray volume of 100 gal/acre on 2 May. Post bloom and fruit development sprays were conducted at 150 gal/acre on 24 May and 28 Jun, respectively. Admire Pro was applied on 19 Apr during the first irrigation through a secondary drip cup under each drip emitter. Drip lines were run for 3 1/2 h and then Admire Pro was placed in the drip cups and dripped into the soil at the same rate as the drip emitter for about 1 h. The drip line was run for an additional 7 1/2 h after the application of Admire Pro. VMB was evaluated in a 1-min search of the trunk on 20 Apr (delayed dormant) and 19 May (first irrigation). Infestation was scored as follows: 0 = no VMB or honeydew, 1 = no VMB but honeydew, 2 = some VMB and honeydew, and 3 = 10 VMB or greater and honeydew. Infestation was evaluated on the cordon and fruit on 22 Jun (post bloom) using the same scoring system. On 26 Jul and 11 Aug (fruit development), ten fruit clusters per vine were examined and each fruit cluster was scored using the same scoring system. Only scores of 2 or 3 were used to calculate the mean percent infestation of the fruit clusters. VMB data were analyzed using ANOVA and means were separated with Fisher’s protected LSD (P < 0.05) (Table 1).

Lorsban Advanced had a significantly lower mean score compared with the untreated check following the delayed dormant application. There was no significant difference among any treatments following the Applaud-delayed dormant application. There was no significant difference among any treatments following the first irrigation application of Admire Pro. Cordon infestation was significantly reduced by Applaud at 24.0 oz/acre, followed by Admire Pro at 14.0 fl oz/acre, Lorsban Advanced at 2.0 pt/acre, Applaud at 12.0 oz/acre combined with Assail at 2.5 oz/acre, and Applaud at 16.0 oz/acre combined with Assail at 2.5 oz/acre compared to the untreated check. All experimental treatments had signicantly lower mean percent infestation compared with the untreated check during the first evaluation of fruit clusters. However, there was no significant difference among the treatments in the second evaluation of fruit clusters. No phytotoxicity was observed with any of the treatments.

This research was supported by industry gifts.