Warm Weather Woes from December for Orchardists

Lack of Chill Hours Leaves Peach Growers Looking at Crop Management Techniques


FOR MOST PEOPLE, this winter’s warmer weather— cre­ated by the El Niño weather pattern— has been a welcome occurrence. However, for growers with peach trees in their orchards, the year’s unseasonably warm and wet weather is a cause for concern rather than celebration. It comes down to the fact that many trees that blossom and bear fruit, such as peaches, require a certain amount of chill hours in order to have the volume come harvest. Chill hours are necessary for the trees to produce fruit that’s optimal in both quantity and quality. Unfortunately, the southeastern region’s warm weath­er means the area’s peaches have not received enough chill hours as of yet.

According to Jeff Cook, a Univer­sity of Georgia Extension Agent with Taylor and Peach Counties, peach trees in his mid-Georgia region need 700 to 1,000 chill hours. “We basically only received about 150 hours of chill from October to December,” Cook shares, noting how few chill hours peaches have received thus far. He adds that the region’s un­seasonably warm weather might be doing harm above and beyond simply occupying hours usually filled by cold tem­peratures. “Some feel that warm weather negates chill hours,” Cook explains. “If this is indeed true, then the above figure [of 150 hours] might be high.” In essence, the warm weather might actually combat the chill hours already recorded, much like warm weather in February will melt snow that fell in No­vember, December, or January.

For peach country further south—such as southern Geor­gia and Florida— the prognosis isn’t much better. In terms of chill hours, “they require less,” maintains Cook, “but they are still very short on the chill hours that they need.” It’s been unseasonably warm no matter how far south you go, and the need for chill hours is present in every peach variety.

Adding to the problem, warmer temperatures in Feb­ruary and beyond are a real possibility. “The cold January temperatures have helped get us closer to an amount of chill that will produce a quality crop,” Cook observes. But, with El Niño still in effect, January’s chilly temperatures might not be enough. Between early January and mid-February, peaches can accumulate about 1,000 chill hours, but more warm weather will obviously put that possibility of getting enough chill hours in question, especially if warm weather does indeed negate chill hours.

If peach trees don’t get enough chill hours, then they will likely produce a late or reduced crop. According to Cook, more warm weather would most likely create problems. “We have reached 50 percent of required chill on most of our va­rieties, so warm weather would begin to push trees to break dormancy,” Cook explains. “This would cause a long bloom period with weak blooms, poor fruit quality, and delayed leaf out. We could see severe crop loss in high chill varieties.”

While growers can’t control the weather, there are a few techniques they can try, according to Cook. “There are some production practices (mostly pruning) that growers are em­ploying,” he points out. “We are also trying to determine if an application of a fruit thinning compound might help set a high quality crop.”