The unusual cold weather this winter is going to have an impact on next year's fruit industry in Indiana, hut how much is yet to be determined.
Bruce Bordelon, Purdue University professor and extension specialist in Viticulture and Small Fruit, says the duration of the cold temperatures can have a considerable impact, as well as the time of year and the condition of the vines going into the fall.
Grapes have a compound bud, with primary, secondary and tertiary growing points. The primaries are usually the first to show cold damage. They are also the growing points that will produce the 2014 crop.
If they are killed, a partial crop may be produced by the secondaries. If both primary and secondary growing points are killed, they would expect considerable cane injury, resulting in little or no crop produced.
There would also be considerable regrowth from older wood, resulting in the need for significant retraining of vines.
Across the state, minimum temperatures ranged from -16 degrees Fahrenheit to 6 degrees the first week of January. Southern Indiana, the main growing region, experienced temperatures of -10 degrees Fahrenheit or above.
At those temperatures, it is expected hardy hybrids and American varieties to have 0-25% bud damage, which is easily manageable, Bordelon says. By adjusting the pruning severity to account for bud injury they can still produce a full crop of fruit.
So far, growers have reported as little as 10% bud damage up to almost complete bud kill. Most vineyards in Indiana, however, grow a mix of hardy and moderately hardy hybrids, so the economic impact may not be severe.
"There are several factors that impact cold injury so it is very difficult to accurately predict damage," says Bordelon. "We will not know the full extent of the damage until March or April, then growers will be able to do an accurate assessment of bud damage and plan their pruning strategy accordingly."