Citrus leaves with diagnostic tunnels of the citrus leafminer. Photo: LSU AgCenter.
A citrus leaf with cold damage including cupping. Photo: Texas Agrilife Extension Service.
Mickey, a local nurseryman, brought in some citrus leaves with cupping and browning. Both Mickey and AHA checked for the tunnels of the citrus leafminer (CLM), but none were observed.
An article, “Managing Citrus Leaf-Miners”, from the LSU AgCenter website provides these treatments for homeowners, nurserymen and landscape professionals, “Homeowners may obtain excellent control of citrus leaf-miners by using spinosad – a natural, organic insecticide formulated for citrus trees in the home garden. Spinosad can be obtained at most local garden centers including most hardware stores under different commercial names such as Conserve, or Naturalyte Insect Control, or Green Light Spinosad, or Success, or Fertilome Borer, Bagworm, Leafminer & Tent Caterpillar Spray, etc.
Spraying for leaf-miners should involve one spray every 5 to 7 days in late evening hours. A total of 2 to 3 treatments may be necessary to gain a good, effective control. Be sure to read and follow the label correctly to ensure a proper and safe mixing and application.”
Because of the lack of CLM symptoms, AHA had images scanned and sent to the Plant Diagnostic Lab in Baton Rouge. Dr. Raj Singh, the AgCenter’s “Plant Doctor”, responded, “This looks like frost injury. Leaves look young and it is possible that frost caused them to curl.”
The AgCenter publishes Louisiana Home Citrus Production, a handy reference for gardeners. This publication describes the issue of freeze protection on page 24, “Temperatures in the mid- to low teens for five or more hours is necessary to kill trees. Temperatures in the low 20s for more than five hours will damage the fruit. The best way to reduce freeze damage is to maintain healthy trees.
Weak trees that show diseases and insect damage or nutritional deficiencies are more susceptible to freeze damage than healthy trees. Cultural practices that
induce and maintain dormancy in the winter will also help trees survive during freezes. They include no late summer or fall fertilization or pruning.”
If you want to contact Roots, Shoots, Fruits and Flowers, please send your questions and pictures to Keith Hawkins, Area Horticulture Agent (AHA), 337-463-7006 or firstname.lastname@example.org. Also, you can be on the “green thumbs” email list by emailing your request to the address above.
“Before you buy or use an insecticide product, first read the label, and strictly follow label recommendations. Mention of trade names or commercial products in this article is for informational purposes only and does not constitute endorsement by Louisiana State University AgCenter.”
“This work has been supported, in part, by the USDA National Institute of Food and Agriculture, Renewable Resources Extension Act Award, Accession Number 1011417.”