Lack of Winter Chilling Conditions
geographic location: Slocum, Tx. Anderson County
Question: We have a peach tree that has peaches but the tree has no leaves. The tree is approx. 8 years old. Also our neighbors have 2 peach trees and an almond tree doing the same thing. What is it and is there anything we can do to help the tree?
geographic location: Katy, Texas
Question: My Bradford Pear tree is not leafing out. It has a few new leaves but they seem limp. I thought it was all leafed out by this time last year. Can you advise.
Your answer is provided by Jim Kamas, Extension Horticulturist in Fredericksburg, Texas. Jim writes:
The problem many growers are seeing in their fruit trees is largely a response to insufficient chilling from this past winter. Deciduous fruit trees need a certain amount of winter chilling to break down growth inhibitors in flower and vegetative buds. Varieties vary by chilling requirement and we recommend varieites based on the "average" number of winter chill hours a given area receives over the years. Remember though, averages are made up from extremes. Planting varieties with a lower chilling requirement than the norm frequently results in crop loss due to early bloom/spring frost.
We used to measure chilling in a given year by simply counting the number of hours during the winter that the temperature was below 45*F. We now know that subfreezing temperatures have little effect in breaking dormancy and that in some cases, temperatures above 65*F during winter can acutally negate some chilling that has previously been accumulated.
In most years of insufficient chilling, bloom is protracted, the blooms usually abort, and the vegetative buds are slow to push. What is happening this year is extraordinary and growers who have been in the business a long time, tell us that the last time they have seen a year like this one was in 1948. In that year, growers reported that they saw ripe fruit and open blooms on the same trees at the same time.
This year has been unusual in that trees bloomed over a long period of time, set some fruit, but are very slow in developing foliage. In response to mid 80 degree temperatures in mid-April, more vegetative buds have started to force. These trees will have an extended harvest and probably have reduced fruit size. Trees that have not yet forced either flower or vegetative buds are struggling to survive. At worst, trees that have a much higher chilling requirment than is called for at a given location may die. For the majority of our fruit trees, however, 1999 will be a year of partial productivity and extended harvest times.
There is nothing growers can do to counteract this phenomenen other than standard good growing practices. Weed control, light frequent applications of fertilizer, and proper irrigation will give trees the best chance of recovery.