Home Industry News Ag Legislation New Leafmining Pest of Wine Grapes in Eastern Washington

New Leafmining Pest of Wine Grapes in Eastern Washington

Leafminer damage of “scribbles” on leaf surfaces was first reported from Washington vineyards in September of 2020. Dr. David James, Washington State University entomologist, determined the damage was caused by a new, undescribed leafmining moth, the first of its kind to damage commercial wine grapes in North America. He conducted a one-year project, supported by the Washington wine industry, to learn about distribution, abundance and potential damage to wine grape vineyards, the seasonality of the pest, and identify potential beneficial predators. 

Key Findings

  • DNA barcoding confirmed the grape leafminer is a unique species of Phyllocnistis, separate from P. vitifoliella and P. vitigenella that are found on grapes.
  • Pheromone-baited traps used for citrus leafminer were deployed in 2021. This lure proved effective for the new grape leafminer, and the pest was detected in 6 of 11 AVAs that were surveyed. Aside from the Columbia Valley AVA, leafminer detections were generally very low.
  • High numbers of adult leafminers in traps and damaged leaves in the Tri-Cities area suggests that this region is where the insect originated.
  • Data indicates this species goes from egg to adult in 14 days, with up to 10 generations from May to September.
  • It seems likely the grape leafminer will principally be a cosmetic leaf pest issue and not cause economic damage to mature vineyards. However, heavy infestations in nursery and newly-established vineyards could cause stunting and poor growth of vines.
  • Although samples collected in 2021 from two leafminer-infested vineyards did not show signs of parasitoids, limited samples the previous year showed the presence of a parasitoid in the Closterocerus genus. Further work is needed to understand the importance of this species in regulating the leafminer.

Read the full article here.

Leave a Reply

Your email address will not be published.