Zinc is an essential plant nutrient, and tree fruit growers need to understand the importance of preventing a Zinc deficiency. Below you will find important information about visual Zinc deficiency symptoms, spray recommendations, and spray timing.
Low levels of zinc and deficiency symptoms are common in eastern Washington. The visual symptom is small, thin leaves. With acute deficiencies, leaves also appear chlorotic (pale yellow) and new growth is limited to a short rosette. The first symptoms of a deficiency with spur-type Red Delicious apples may be a limited number of small leaves on spurs, poor fruit set and small fruit size.
Soil applications of zinc have not been effective except with young trees where applications have been worked into the soil prior to tree planting. Effects can last for 3 to 5 years. Spray applications of zinc are required with established trees. Annual applications are more effective in preventing deficiencies than making applications at high rates every 2 or 3 years. Ground sprayer applications are more effective than those by aircraft because they give a better distribution of zinc to the lower and inside portions of trees where weak spurs, lower levels of zinc and small fruit size are greater problems.
Where zinc levels are known to be low, make annual spray applications at low rates, either after harvest in the fall while leaves are still green and active, or as a dormant spray in the spring. Higher rates of zinc can be applied in the early spring than in the fall. With an acute deficiency, both a fall and spring application may be necessary.
Where deficiency symptoms are observed during the growing season, avoid the use of zinc sulfate because of potential injury to fruit and foliage. Various zinc chelates and organic complexes are available which reduce the potential for injury. They differ in their compatibility with oil, and in their effectiveness, particularly in correcting deficiencies. Follow manufacturer’s directions carefully.
Washington State University Research
Nutrient Technologies, growers, and PCAs have had great success with all Tech-Flo products. Our unique manufacturing process results in micronized, chemically reacted particles to provide plants with safe, effective nutrients in a form the plant can easily use. The addition of Polysorbygen provides superior wetting and sticking characteristics and improves rain fastness.
Tech-Flo products can effectively help you promote adequate levels of zinc in tree crops like apples, pears, and cherries. It can be used:
- post season applications in the fall
- dormant applications in the spring
- throughout the growing season
You can also download our mobile app to help identify deficiencies by crop and nutrient, and get instant recommendations for products to help you grow.