In the past, grape growers have mistaken any shrivel in their fruit for grape berry shrivel, also known as sour shrivel, says Washington State University’s Dr. Bhaskar Bondada. In a panic, some were needlessly thinning clusters to remove what they thought were berries afflicted with sour shrivel.
It’s important to know the difference between shrivels because fruit from some types can still be made into wine, but grapes with sour shrivel can’t. To help growers identify grape shrivels, Bondada and his colleagues have developed diagnostic keys for various ripening disorders in the form of a poster with photos to provide characteristics and distinguishable features of the different shrivels.
Several theories about the cause of sour shrivel have been disproven in past WSU research. Bondada’s current focus is on the mechanics of sour shrivel, comparing the structure and functionality of vascular pathways (the xylem and phloem) of the whole bunch stem of healthy and sour shrivel afflicted vines.
The research involves simulating sour shrivel symptoms under greenhouse conditions and examining vascular pathways, especially phloem that translocates sugar, in different organs for some kind of occlusion that may be impeding sugar flow into the berries.