Berry shrivel affects between 5 to 10 percent of Washington’s grape crop, according to a recent Washington State University survey.
Questions about the disorder were included in a Washington grape industry irrigation survey conducted last year by Dr. Mercy Olmstead, WSU Extension viticulture specialist. Respondents represented 12,000 acres of wine grapes and 700 acres of juice grapes.
"It’s enough of an issue that some growers are cutting out shriveled berries from clusters before harvest to keep the inferior fruit from contaminating the rest of the crop," she said. "The shriveled berries contain a huge amount of malate. They’re gross. The berries taste really sour."
Survey results showed a correlation between regulated deficit irrigation and berry shrivel, she noted. "But then, most of the shrivel-affected varieties are red, and most growers apply regulated deficit irrigation to varieties that are red."
The survey showed no correlation between the disorder and soil type, changes in the amount of water, or type of irrigation (micro sprinkler/drip versus overhead sprinkler).
"But we did learn that growers need more education about the types of shrivel they are seeing in the vineyard," Olmstead said, adding that most of the shrivel described by growers in the survey was likely due to sunburn and dehydration, shrivel types that can be minimized by management practices.