Keep fruit trees vigorous and healthy to prevent pest problems.

The Safest Insecticide for Plum Curculio

by Amanda Flanigan

While you and your children harvest the fruit from your backyard orchard, be on the lookout for a dark-colored beetle crawling along the tree. These damaging insects are called plum curculio and will require immediate action with sprays of insecticide to prevent further damage to your plants. Choosing the safest insecticide for plum curculio reduces the need for unnecessary chemicals that pollute the environment and put your children’s health at risk.

Evil Weevil

Plum curculio (Conotrachelus nenuphar) is a serious pest of stone fruits, especially plums (Prunus spp.), hardy in U.S. Department of Agriculture plant hardiness zones 3 through 9; peaches (Prunus persica), hardy in USDA zones 5 through 8; cherries (Prunus spp.), hardy in USDA zones 4 through 7, and other soft-skinned stone fruit. Plum curculio causes mostly superficial damage to apples, hardy in USDA zones 4 through 9. The brown, black and/or gray weevil isn't hard to recognize with its beak-like, curved snout. It lays eggs inside the fruit, and the larvae also feed on the fruit. The plum curculio's feeding results in brown rot of the fruit and reduces crop yield. Damaged fruit may fall from the tree prematurely. The infected fruit skin develops crescent-shape blemishes that swell and knot.

Safest Insecticide for Plum Curculio

For the safest insecticide to remove plum curculio, choose an organic product. Protectant barrier sprays containing kaolin are the only organic insecticide option for plum curculio control, according to "Organic Gardening." Kaolin is a soft, white clay used in products that when sprayed on the tree, forms a protective barrier. It also protects the plant from heat stress and sunburn. It is safe to use on fruit trees and can be applied up to the day of harvest. The kaolin spray is mixed with water before thoroughly covering the foliage and fruit of the tree liberally. The exact mixing instructions vary depending on the brand of kaolin protectant spray used. One brand, for example, suggests mixing 1/4 to 1/2 pound of the kaolin with 1 gallon of water. Due to the clay, fruit will look strange, and kaolin products should be used in conjunction with proper care, maintenance and sanitation to ensure complete protection against plum curculio.

More Organic Control

Manually control plum curculio by shaking the insects out of the infested tree and onto a cloth positioned under the tree. The fallen bugs should then be collected and destroyed before they can lay more eggs and infest other trees. The Missouri Botanical Garden website suggests performing this management option in the early morning hours when the insects are sluggish. Furthermore, all fallen fruit must be regularly removed and destroyed. The fallen fruit could house eggs or larvae hidden inside, which will emerge and re-infest the tree.

Warnings and Considerations

Even though kaolin is relatively safe, care must be taken when handling the product. Kaolin can cause lung irritation if inhaled and mild eye irritation. Only apply when children and pets are not present and wear safety goggles, dust mask and rubber gloves when using this product. For contact with eyes, flush with water for several seconds and -- if needed -- contact poison control. If ingested, call poison control center immediately.

About the Author

Amanda Flanigan began writing professionally in 2007. Flanigan has written for various publications, including WV Living and American Craft Council, and has published several eBooks on craft and garden-related subjects. Flanigan completed two writing courses at Pierpont Community and Technical College.

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