Wednesday, June 17, 2020

Spider Mites

Cotton Insect Report

Following Tropical Storm Cristobal, spider mites are still building in parts of central Alabama. Spider mite infestations are rarely evenly distributed throughout the field and are almost always in clumps either near field edges or randomly throughout the field. Our threshold in the Alabama Cotton IPM Guide says to treat fields when mites are widely distributed and mottling of leaves is common. Determining when to implement controls can be difficult when trying to decide how many ‘hotspots’ suggest mites are “widely distributed” and justify a spray. Spider mites prefer hot, dry conditions and typically can be “beaten back” by a rainfall event. Fields with spider mite hotspots should continue to be monitored after rain, because populations can build back after several days of hot, dry conditions. Spider mites also tend to build following broad-spectrum insecticide applications for other pests.

To scout for spider mites, look for leaf stippling or reddening on the top of leaves. If these symptoms are observed, look on the underside of leaves for spider mites, which will be a yellowish color with two black “spots” on each side of its back. Exposing the underside of leaves to the sun may agitate mites, making them easier to see. Also look for mites one or two nodes above the most symptomatic leaves as they may have moved up to fresh leaves. There are a few miticides labeled for use in cotton that can be found in the Cotton IPM Guide. Abamectin (e.g., Agri-Mek 0.15EC) at 8-12 ounces per acre is the most economical option but rotating chemistries is necessary if multiple applications are needed. Historically, lower rates of abamectin (8-10 oz) have provided adequate control in younger cotton, while higher rates (12 oz) are needed later in the season when plants are larger.

Peanut Insect Report
We were recently notified that Nichino America received a supplemental label for the miticide Portal to use in peanuts. The labeled rate is 1.0 – 2.0 pints per acre with a minimum of 14 days between applications. The supplemental label must be in the possession of the user at the time of application.

Scott Graham and Ron Smith