Kaolin clay sprays are an important organic orchard strategy used after petal fall to repel many types of pest insects and protect trees from sunburn and high temperatures. Kaolin clay repels pests by making the fruit tree an unsuitable environment for certain insects to land, feed and lay eggs. The tiny clay particles serve to disguise the target fruit and can clog the eyes, ears and reproductive organs of many common pest insects including apple maggot, plum curculio, codling moth, european apple sawfly, oriental fruit moth, tufted apple bud moth, white apple leafhopper, and pear psylla.
It is important to build up a proper covering of clay on your trees or it will not be effective. Spraying at least 3 times, each application a week apart, after initial petal fall is recommended. A sprayed tree will be coated my a thin white film of clay particles. Be careful not to overspray, as too much clay can negatively effect mite predator insects and possibly trigger a red mite infestation. Repeat applications after any major rain event are also recommended to provide ongoing protection from pests.
While Kaolin clay is a natural product, it is still important to protect yourself while spraying. Long sleeves, long pants, and closed toed shoes are recommended. A mask or respirator is also necessary to prevent inhalation of clay particles.
Instructions for using a backpack or handheld sprayer:
• Mix 1/4 to 1/2 lb (approximately 3 cups) of Surround WP or Surround At Home per one gallon of water. If your sprayer is not easy to shake, premix in a container and pour the mixture into your sprayer
• Add the powder slowly to approximately 1/4 of the water you will be using, stir and mix well by shaking vigorously for 30 seconds.
• Add the remaining water and shake for an additional 30 seconds.
• Shake the sprayer occasionally during application.
• Thoroughly coat all leaf and fruit surfaces until they appear white.
• When finished, spray until the sprayer is empty and flush the system. Leftover mix can be used within 2 weeks to avoid spoilage.
Surround can be purchased in 5lb or 25lb packages. The 5lb packages average around 25 dollars while the 25lb commercial variety average around 50. Because the clay will not spoil for many years, you can buy in bulk, save money and use it for multiple years.
These products are also available at many garden centers and farm supply stores.
For more information of Kaolin:
This edition of POP TIPS prepared with help from 2015 POP orchard intern Sophia Taylor.
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