Departments of Plant Pathology and Entomology
North Carolina Cooperative Extension Service
North Carolina State University

FRUIT
AND
VEGETABLES

North Carolina Pest News
Volume 12, Number 3, May 9, 1997
Stephen J. Toth, Jr. and Thomas A. Melton, editors

The information and recommendations in this newsletter are applicable to North Carolina
and may not apply in other areas.

From: James F. Walgenbach, Extension Entomologist, Mountain Horticultural Crops Research and Extension Center, Fletcher

Insect Activity on Apples

In the foothill and Piedmont apple production areas of North Carolina, codling moth populations have accumulated about 250 degree days since biofix, which is the optimum timing of the first of two insecticide sprays targeted for the first generation of codling moths. Insecticides of choice at this time are either Guthion or Imidan. In the higher elevations (i.e., Henderson, Haywood and Wilkes Counties), we are still at least a week from reaching the 250 DD figure. In orchards where codling moths are historically a minor problem or where pheromone trap catches have not exceeded 7 moths per trap to date, a single application of insecticide timed at 360 DD will be sufficient. If growers are not monitoring populations with pheromone traps in their orchards, they should use two applications for the first generation.

First generation tufted apple bud moth populations are increasing, but we are still at least 3 weeks from the need for insecticidal control. Growers are often concerned about high pheromone trap catches, but should be reminded that egg hatch does not begin until 7 to 10 days after peak trap catches. A preliminary egg hatch model from last years data suggested that the first insecticide application for tufted apple bud moths is not needed until 700 to 800 DD after biofix. To date, only about 200 and 350 DD have accumulated in Henderson and Polk Counties, respectively. Lorsban or a Bacillus thuringiensis product (Biobit, Dipel, Javelin, Xentari) are the preferred choices of insecticide for tufted apple bud moths.

Pyramite Receives Federal Label for Apples

On May 7, the U. S. Environmental Protection Agency issued a Section 3 registration for the miticide Pyramite 60WP on apples for control of the European red mite. A state registration is anticipated within approximately a week. Pyramite will be available in 4.4 oz. water-soluble bags (5 bags per case). The label recommends 4.4 to 6.6 oz. per acre. In research results from 1996, the 4.4 oz. per acre rate provided excellent knockdown and long residual control of a high mite population.

Pyramite is recommended for curative control of European red mite populations. It is extremely active against all life stages of the European red mite, and provides up to 55 days residual activity. European red mite threshold levels on apple are 2 to 3 mites per leaf on Red Delicious cultivars that are susceptible to Alternaria blotch, and 7 to 10 mites per leaf on all other cultivars.

From: Kenneth A. Sorensen, Extension Entomologist

Strawberry Insect Pests

Mite populations remain high in several strawberry fields in the Piedmont and eastern North Carolina. Growers in Wake, Franklin and Brunswick Counties report populations of mites averaging 20 mites per leaf. With hot, dry weather these levels of mites can expand very rapidly. With harvesting in full swing, any miticide application must have a short interval between the last application and harvest. Vendex is the material of choice with a 1-day time limitation to harvest. Applications of 50 gallons of water and the 1 pound rate of Vendex is suggested. High-pressure sprays directed to the undersides of leaves are required for good mite control. A second application may be needed after 3 to 5 days if mite counts remain high and hot, dry conditions exist. Insecticidal soap at 2 percent would give some knockdown of mites and might be used in some situations where a 0-day waiting period is necessary. Consult product labels and the North Carolina Agricultural Chemicals Manual for specific information. From our tests and reports from other states, it is to late to introduce predatory mites and achieve control.

With good horticultural practices, strawberries should be harvested in good supply over the next 4 weeks. Be alert for sap beetles that are attracted to overripe, diseased or injured fruit. Refer to the insect note on sap beetles for more information on sap beetle management.

From: Marc Cubeta, Extension Plant Pathologist, Vernon James Center, Plymouth

Late Blight on Potatoes

Late blight has been identified in a potato field in Washington County. Potato growers are strongly encouraged to apply a protectant fungicide if they have not done so already. Repeated protectant fungicide applications may be needed, particularly if cool, wet weather conditions occur within the next two weeks. Growers with questions should contact their county Extension agent or an Extension specialist.

Web page last updated on May 12, 1997 by Stephen J. Toth, Jr..

This Web version is a cooperative effort between the North Carolina Cooperative Extension Service and the Center for Integrated Pest Management