Grape growers in the new revised core area (reduced from 1,000 meters to 500 meters) are strongly encouraged to spray first-generation European grapevine moth (EGVM) to ensure there are no further finds of EGVM in the quarantine zone. With no further finds, the quarantine is expected to be lifted by the end of 2011. According to the University of California entomologist, at least two sprays are needed to cover this prolonged emergence of adults from diapause. Emergence may begin as early as the first week in April and continue through the end of May. Adult moths that emerge are not strong flyers and will lay eggs on grape flower buds, and olive flowers in this first generation.
A total 37 day-degrees have been accumulated so far this year since March 15 in the Del Rey area. Since there really is nothing for moths to lay eggs on, or larvae to feed on, if eggs were to hatch, we are probably early for a bio-fix. Based on historical temperatures we will arrive close to 100 day-degrees the first week in April. Since we have not and do not want to catch any EGVM moths, we will be estimating as to when moths will begin to fly (bio-fix). If there are pupae that overwintered from last year, they will be emerging this spring and most likely will be caught in the more extensive trapping program this year.
A total of 7,500 EGVM traps are up in Fresno County, deployed at 100 traps per square mile in the core area and 25 traps per square mile in the rest of the state.
The university recommendation for EGVM treatment for the first generation spray timings is April 15th through 21st for the first application with another followed three weeks later.The second application should be applied from May 5 through the May 12. With both treatments the first generation will be covered. Long residual ovicide/larvacide materials like Intrepid or Altacor should be the first choice based upon efficacy and cost. These materials need to be applied prior to egg-laying to be most effective. Always follow all label restrictions.
There is a University of California approved list of materials for EGVM on the UC website link: http://cenapa.ucdavis.edu/news_970/European_Grapevine_Moth_688/?newsitem=25609
Two new additions to that list will include Kryocide/ Cryolite and Agri-mek that have been shown to control EGVM. Growers should be able to mix these materials with their normal fungicide or insecticide spray programs. If growers need advice on materials to use and timing, they should consult their pest control adviser (PCA), the University of California, or the EGVM coordinator for choices of materials and timing.