Primary cause of grape cracking still elusive

(WesternFarmPress) - A mysterious syndrome that leads to cracking on grapes is still under investigation by University of California researchers. Under current study is whether Ethephon, a spray used to promote berry color, is largely responsible for grape berry cracking.

Grape berry cracking is not a new phenomenon. It has been found for more than two decades, according to Mark Matthews, professor and plant physiologist in the Department of Viticulture and Enology at the University of California, Davis.

Matthews discussed grape berry cracking in Fresno, Calif. in June during a San Joaquin Valley Winegrowers Association meeting. He told growers that for all the work that continues on the subject, a clear cause of grape berry cracking still eludes researchers.

“We’re not clear on whether cracking comes before bunch rot or if bunch rot comes first,” Matthews said. “It’s also not clear how we manage it.”

Grape berry cracking does not seem to be a widespread problem, according to Matthews. Flame seedless table grapes and Zinfandel wine varieties appear to have higher rates of cracking.