Wednesday, May 24, 2017

Suhas Vyavhare & Katelyn Kesheimer, Texas A&M AgriLife Extension

It’s go time for the cotton planters on the Texas High Plains. Planter wheels are turning throughout the region with clouds and patchy rain loomed in the forecast. There has been some early planting underway and we already are seeing some emerged cotton. Wireworms will be one of the first pests you will see in the Texas High Plains cotton.

The wireworm adults (click beetles and darkling beetles) become active in early spring and lay their eggs in the soil in clusters. The adults, as well as the larvae produced from the late summer and fall egg-lays, overwinter in the soil in leaf litter, stubble, or other suitable habitats. Wireworms attacking cotton tend to be most severe following grains crops, especially sorghum, fallow or weedy ground, or in reduced-tillage systems.

Click beetle

Darkling beetle

Wireworm larva
Most damage is inflicted by larvae, although some darkling beetle species can girdle or clip seedling cotton off at the soil surface much like a cutworm. The larvae damage cotton by feeding on the root, hypocotyl (stem of the germinating seedling), and cotyledon (seed leaves) of plants before emerging from the soil.  Root feeding can kill plants, but usually results in stunting. The most severe damage occurs when the hypocotyl is severed resulting in plant death and stand reduction.

Planting shallow and under warm conditions often allow cotton seeds to germinate rapidly and for plants to outgrow wireworms. From planting to 4-5 leaf cotton, darkling beetle adults should be watched for invading cotton from pastures, weedy areas, and corn and sorghum stubble. These beetles are only a threat if they cut off the seedling plants resulting in stand reduction. Treat for wireworm adults only when encountered in large numbers, plant clipping is evident and unacceptable stand reduction probable. Insecticidal seed treatments are the most effective means of preventing wireworm damage. More information on wireworm damage and control tactics can be found at: http://lubbock.tamu.edu/files/2017/05/Wireworms_ENTO-068.pdf