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Demonstration and Evaluation of Pest Management Alternatives in Finger Lakes Grapes 2000

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Principle Investigators: T. Martinson, Area Extension Educator, Finger Lakes Grape Program, T. Weigle, Senior Area Extension Educator NYS IPM Program

Collaborators: G. English-Loeb and J. Nyrop, Department of Entomology, NYSAES; Wayne Wilcox, Dept. Plant Pathology, NYSAES; Andrew Landers, Dept. of Agricultural and Biological Engineering, Cornell University, Ithaca, and D. Gonsalves, Dept. Plant Pathology, NYSAES, Geneva, NY

Summary:

Several small experiments and demonstrations supporting adoption of improved spray technology and pest management alternatives by Finger Lakes area grape growers were completed.

(1) Spray trials with an electrostatic sprayer (ESS) showed roughly comparable spray deposition and fairly comparable disease control to areas treated with a conventional airblast sprayer. In a spray rate reduction experiment with the ESS sprayer, control of powdery mildew and botrytis declined at 50% and 25% of labeled rates. This suggested that reducing rates with the ESS sprayer would not be advisable, despite potentially better coverage with the ESS sprayer at much lower spray volumes than with conventional airblast sprayer. The potential for new spray equipment to reduce drift and improve spray deposition was explored through three field demonstrations organized by the Finger Lakes Grape Program and Dr. Andrew Landers.

(2) Sprayable grape berry moth pheromones, if effective, would be more likely to be adopted by growers, who are resistant to hand-applied pheromone ties. Tests this year in three vineyards were inconclusive, due to a lack of grape berry moth pressure in both pheromone-treated and untreated blocks.

(3) Releases of predatory mites for controlling european red mites (ERM) were made in 10 vineyards, half of each treated with EBDC fungicides, and half of each block with no EBDC fungicides. Releases did not increase predator numbers over naturally-occurring levels, but pest mite ERM numbers were higher where EBDC fungicides had been used, due to the fungicide’s effect on predatory mites. Predatory mites provide biological control of ERM, except where they are impacted by EBDC fungicides. By carefully modifying spray programs, growers can maintain biological control. Grape varieties differ in leaf pubescence (hairiness), and pubescent leaves harbor more predatory mites than glabrous (hairless) leaves.

(4) Replacing tomato-ringspot virus infected vines with grafted vines can restore productivity of hybrid grape vineyards. Experimental grafted vines planted in 1999 were tested for virus. All 68 samples tested negative for the virus. Continued periodic testing of grafted vines will be necessary to verify that they remain virus free in the field. Several commercial growers in the Finger Lakes are planting grafted vines as replacements in ringspot-infested blocks.

(5)Reducing the application rate of imidacloprid (Provado) by 50%, from 0.75 oz/acre to 0.375 0z/acre, had no effect on the level of eastern grape leafhopper suppression. It appears that reduced rates may save growers money without affecting the level of suppression provided by this new low-risk insecticide. Reducing the cost of application will allow growers to substitute provado for less-expensive but more toxic insecticides, many of which are at risk of cancellation following Food Quality Protection Act (FQPA) review.

(6)The striped snail, Cepaea nemoralis, has appeared as an unwanted contaminant in machine-harvested grapes, causing economic losses to growers due to processor rejection of snail-contaminated bins of grapes. Keeping snails out of the canopy is the key to preventing these losses. Insecticides are largely ineffective. ‘Sluggo’ brand bait, made of iron phosphate, proved as effective as metaldehyde bait, potentially toxic to wildlife, in keeping snails out of canopies. Copper based sprays directed at grape trunks, or copper barriers placed around trunks offer great promise in keeping snails out of grape canopies. Copper barriers appear to be 100% effective, and offer growers a simple, long-term, environmentally friendly solution for growers.