Hickory Shuck Worm in Pecan

Plant Health Clinic Disease Note Issue 33

Sherrie Smith and Jason Pavel

Hickory/Pecan Shuck Worm-Cydia caryana. Photo by Sherrie Smith, University of Arkansas System Division of Agriculture

The larvae of the hickory shuck worm, Cydia caryana, can cause significant damage and yield loss to pecan crops. The adult is a nocturnal inconspicuous small gray to smoky black moth approximately 3/8 inch long with a ½-inch wingspan. Adult moths emerge from the previous year’s shucks in the spring, mate, and lay eggs on newly developing pecan or hickory nutlets, or phylloxera galls.

What are the symptoms of hickory shuck worm feeding in pecans?

Their feeding activity causes the little pecans to drop. The second-generation feeds on larger nuts, also causing premature nut drop. The third generation does the most damage, mining the nuts, reducing nut fill, and causing the shucks to cling to the shell.

How do I prevent hickory shuck worm in pecans?

Raking up fallen nuts in the fall helps to control overwintering shuck worms. Trees should be sprayed at half-shell hardening and repeated at 2-week intervals until shuck split. Asana XL, Belt, Dimilin 2F, Intrepid 2 F, Mustang Max, Spin Tor, warrior, and Entrust are labeled for control.

Hickory/Pecan Shuck Worm-Cydia caryana. Photo by Sherrie Smith, University of Arkansas System Division of Agriculture

Take Aways:
• Rake up all fallen nuts and burn or dispose off the property.
• Spray at half-shell hardening.
• Repeat at 2-week intervals.

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This work is supported by the Crop Protection and Pest Management Program [grant no. 2017-70006- 27279/project accession no. 1013890] from the USDA National Institute of Food and Agriculture