We are still detecting grape root borer adults in north Georgia. This means that the adults are still active, with females potentially still laying eggs. While we are getting a little late for chemical control, if you have more than 35 days before harvest, you can use Lorsban 4E* (chlorpyrifos).This is currently the only insecticide registered for control of grape root borer, which is applied as a coarse spray to the base of vines to kill adults as they exit the soil and newly hatched larvae before they enter the soil and plant roots. Follow the label instructions and see the Southern Region Small Fruits Consortium for recommendations.
If you are finding grape root borer moths this year and are concerned for your vines, but it is too late for management, I recommend monitoring for the moths next season.
Grape root borer adults can be monitored using a simple bucket trap and pheromone (pictured above). Traps and pheromone can be purchased from sites like Great Lakes IPM* (assembly instructions can be found here). Collection of grape root borer moths in the traps not only alerts you to the potential problem, but can also be used to determine the initiation of insecticidal treatments.
Furthermore, if you would rather not rely on insecticides for management, another effective management strategy is called, “mating disruption.” Through the deployment of pheromone-filled dispensers (pictured above) within your vineyard, mating disruption works by making it difficult for males to find females to mate, and without mated females, there are no new larvae to attack the vines. The entire vineyard needs to be under mating disruption for at least two years, but after two years of use, it is really effective at reducing the grape root borer within the vineyard. The mating disruption (Isomate GRB) can be purchased through Helena Chemical Co* (828-685-1182).
If you have any questions about the management strategies discussed here, please let me know.
Additional information about grape root borer management, please click here.
*Does not imply endorsement of named vendor over other options