Potato Leafhopper In Young And Mature Vineyards

In the past few years, Michigan winegrape growers have been dealing with an increased presence of the potato leafhopper. While this pest has a broad host range of more than 100 crop and non-crop plants, winegrapes can be a popular target for them. Feeding by the potato leafhopper causes stunted vine growth, yellowing, and leaf cupping.

Recently, a team of researchers at Michigan State University looked at cultivar susceptibility to potato leafhopper, as well as response from potted, young and mature vines.

Vine Response: Young Vineyards

In a Pinot Noir vineyard planted in May 2008, vines were open to potato leafhopper infestation for zero, one, two, and three weeks in 2009 and 2010. Half of the vines were cropped (three clusters in 2009, 15 clusters in 2010), and half had all clusters removed. The clusters were harvested and measured for Brix and pH.

After three weeks, both in 2009 and 2010, the cluster-removed vines saw a significant increase in the number of yellow leaves per vine.

Vine Response: Mature Vineyard

In the mature vineyard, six vine plots were established in a mature Pinot Noir vineyard. Potato leafhopper was controlled in half of the plots using an insecticide. The vines were cropped to high (4.7 tons) or low (2 tons) levels in August 2009.

It was found that there was no significant effect of potato leafhopper or crop load on fruit quality (Brix or pH) in 2008 or 2009.

Information from this story was presented by a team of Michigan State University entomologists and horticulturists at the Great Lakes Expo in Grand Rapids in December. For more information, you can find the presentation at www.glexpo.com.