Controlling grape root borer with pheromones
The grape root borer is an insect pest native to the Eastern U.S. The larval stage of the moth can do significant damage, living at least two years and possibly longer in the soil feeding on grape roots. They can destroy and kill mature grape vines. The most widely used control method involves using a restricted-use organophosphate pesticide, which is expensive and time consuming. Recently a new pheromone system has become available for use in grape root borer mating disruption. This system utilizes the pheromone mix of the European leopard moth, which differs from the pheromone mix in the standard grape root borer pheromone lure. Each of the new pheromone dispensers contains 80 times more pheromone than the standard grape root borer pheromone lure currently available. The new dispensers are labeled to be placed in the vineyard at a concentration that releases 300 times more pheromones than the standard grape root borer pheromone lures used in our previous NESARE projects. The effectiveness of the new pheromone system has been deemed successful by the inability to trap male grape root borers in a vineyard. The inability to trap male insects is known as trap shutdown. Utilizing trap shutdown as an indicator of mating disruption success is questionable.
Grape root borer populations in our vineyard never decreased utilizing the standard pheromone lures in previous projects, although the numbers did not increase. The aim of the multi-year project will be to test the new system at different rates and its effectiveness in reducing or eliminating grape root borers in our vineyard. The new pheromone system will be utilized for two years. In the third year only traditional pheromone traps will be placed in the vineyard to determine if the new pheromone system has been successful in reducing the grape root borer population.
In the summer of 2016 testing on the effectiveness of Isomate GRB pheromone dispensers was continued. The vineyard test area was divided into 9 blocks with 3 plots each. On June 24, a standard bucket trap with a grape root borer pheromone lure was placed at the center of each plot. Being the third year of testing no Isomate GRB dispensers were placed in the vineyard in 2016. If the Isomate GRB dispensers were effective the two previous years, a significant reduction in the number of male GRB captured should occur. The first four male grape root borers were captured in the vineyard on July 5th. Male grape root borers were captured throughout the summer with the last two being caught on August 12th. A total of 313 grape root borers were captured during the summer with a peak of 97 on July 18th.
In the two years when Isomate GRB dispensers were placed in the vineyard only two male grape root borers were captured in the pheromone traps each year. In the previous five years (2009 – 2013) with 27 pheromone traps in the vineyard, an average of 426 male grape root borers were captured in the vineyard each year. The average for the eleven years preceding the Isomate GRB study was 347 per year.
The Isomate grape root borer dispensers definitely caused a substantial decrease in the capture of male grape root borers in the pheromone traps in 2014 and 2015. Isomate GRB dispensers do cause substantial trap shutdown, but do not appear to be effective in preventing grape root borers from mating. In 2016, after two years of placing Isomate GRB dispensers in the vineyard, a total of 313 male grape root borers were captured in the pheromone traps. With a larval lifespan of one to two years it is obvious that mating occurred during the two years of using the Isomate GRB dispensers. Mating was also observed during the years the Isomate GRB dispensers were in the vineyard. In 2015 a mating pair was observed just 112 inches from an Isomate GRB dispenser and in 2014 mating occurred 174 inches from a dispenser.
A field day detailing the progress of the project was held at the vineyard on August 24. A presentation on the project is scheduled for the Mid-Atlantic Fruit and Vegetable Convention on February 1, 2017.
Penn State University
1383 Arcadia Road
Lancaster , PA 17601-3184
Office Phone: 7173946851