Scaffolding on an insufficiently cooled peach tree. Note the sufficiently cooled trees in the background. (Photo: Gregory L. Reighard) The problem with many varieties with low refrigeration requirements, Chavez says, is that the plants meet their minimum cold requirements, only to flower too early and then likely struggle with frost conditions. He points out that even during warmer winters, farmers can find ways to maximize their yields. Once a plant`s cooling needs are met, buds slowly begin to break dormancy when temperatures exceed 40 degrees F. Each type of fruit plant and variety has a specific heat unit or hourly growth degree (GDH) to achieve a certain level of bud, flowering and fruit development. “It`s not advisable to plant a tree that requires 1,050 hours of cooling when your area historically only gets 650,” Vinson said. History seems to be repeating itself. Brennan isn`t the only expert who believes 2018 won`t repeat last year`s problems. Many are cautiously optimistic that this year will be a good year for peach production.
“It`s a precarious situation because peach trees in soil X need cool hours, and it`s a problem if they don`t get them,” he says, adding that some trees were still trying to “wake up” in May 2017, two to three months later than normal. “I hope this is not a trend that will end up keeping us out of fisheries production.” If you are mourning the loss of your tomato and basil plants after the recent frost, have courage, the peaches are coming! For more information on growing fruit trees and rest periods, visit Aggie Horticulture`s website in aggie-horticulture.tamu.edu/ or contact Kate Whitney, Williamson County Horticulture Extension Officer in klwhitney@ag.tamu.edu. Of the models tested in Alabama, the Modified 45 provided the best prediction of when calm will be offset by cold temperatures. Compared to other models tested in Alabama, this model uses a more sophisticated method to determine when dormancy actually begins in the fall (rather than arbitrarily using October 1 as the start date) and measures hours at or below 45 degrees F. It does not take into account the negative effects that high temperatures can have on cooling buildup, and it counts cooling hours below 32 degrees F. However, after five years of study, the Modified 45 proved superior to Utah, Florida and Old 45 methods for measuring cooling under Alabama conditions. Like all deciduous trees, peach trees lose their leaves and rest in the fall, but that`s not all. When winter continues, the trees enter a time called rest.
It is a period of deep rest during which a short rush in hot weather is not enough to wake the tree. The cooling needs of peach trees depend on this rest period. Why do fisheries need cold? Without this period of rest, the buds planted last summer cannot bloom. If there are no flowers – you guessed it, no fruit! So, here we go. The next time you`re at a party and someone asks, “Why do peach trees need cold?” you`ll get the answer; Or when you plant your next peach, you can be sure it`s right for your area. If you can`t determine the refrigeration needs for fisheries in your area, your local extension office can help. “Fruit growers are very adaptable or they wouldn`t be working on a high-risk, high-yield farm,” says Reighard. “Southeast peach producers can expand their market windows at the beginning of the season with higher quality varieties that will likely require less pesticides and water consumption in mid and late summer, as earlier harvests and sufficient vegetative growth would have occurred as early as July for more varieties. Standard peach varieties have winter cooling requirements of 450 to 1,200 hours below 45 F between 1. November and end of February. These peach trees bloom and do not bear fruit in warmer climates.
Fortunately, horticulturists have developed several varieties with refrigeration requirements of less than 450 hours, meaning you can grow them in U.S. Department of Agriculture hardiness zone 10. “The outlook for proper refrigeration of fisheries in the Southeast has improved significantly after a colder-than-normal January for a La Niña winter,” said Gregory L. Reighard, Ph.D., professor emeritus at Clemson University. “2018 could be a good year.” It`s important to first look at how much cold your area historically receives when growing peaches. Cold requirements for peaches that fall below 500 hours are considered low-cold peaches, and most are adaptable to areas where nighttime temperatures drop below 45 degrees F (7 °C) for several weeks and daytime temperatures remain below 60 degrees F (16 °C). Bonanza, May Pride, Red Baron and Tropic Snow are good examples of low-cold peaches that range from 200 to 250 hours, although there are many others of equal reliability. Are peach cooling requirements important to you, the home gardener? If you want to have a peach tree in your garden that gives you more than shade, you`re damn important. Among the many varieties, there is a huge variation in cold requirements for peaches. If you want peaches, you need to know what the average peach cooling times are in your area. Plants enter the resting or resting phase when the level of growth-regulating chemicals in the buds changes. In other words, as growth regulation inhibitors increase and growth regulating promoters decrease, plants begin their resting phase.
Since the cooling needs of a facility are met by cold temperatures, the promoter content begins to increase, while the inhibitor content decreases. The higher content of promoters in the buds allows a normal resumption of growth and flowering in the spring, when cooling requirements are met. If you live in an area with warm winters and want to grow juicy peaches, do not despair. You have a choice. Peach trees bud in summer and rest in winter. They need enough hours of temperatures below 45 degrees Fahrenheit in winter, called cold requirements, for their buds to open in the spring. This prevents them from opening too early and seeing their flowers destroyed by late frosts. Since the cooling needs of a variety are the average temperatures that trees need, each bud produced can have an ideal cold higher or lower.
