WSU-TFREC

GROWTH REGULATOR SPRAYS

contributed by Dr. Kathleen Willemsen
WSU-Tree Fruit Research & Extension Center

A number of different kinds of responses can be obtained from the application of various growth regulators. The response varies with the chemical and the condition or stage of development of the tree and fruit. Therefore, before you apply a chemical you should understand how it affects the tree or crop and the important side effects.

The degree of effect depends on how much of the material is absorbed and the condition of the tree. Factors such as cool weather, slow drying conditions, and good foliage will increase the response. Although poor foliage reduces absorption, weak trees will generally be overly sensitive to even small amounts of growth regulators. Concentrating sprays increases the concentration of the chemical, which can cause injury. Similarly, adding a surfactant, unless so indicated, can result in greater absorption and possible injury.

APPLE PEAR STONE FRUITS
Thinning Stop-Drop Growth control (suckering & flowering) Thinning Stop-Drop Growth control Fruit quality
Bloom
Post-bloom

Washington State University
Tree Fruit Research and Extension Center
1100 N. Western Ave.
Wenatchee WA 98801

phone: 509-663-8181
fax: 509-662-8714


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May 2, 2000