Spider Mites (Tetranychidae)
Two-spotted spider mites.
Spider mite problems are most common in southwestern Kansas. Infestations develop on the undersides of lower leaves and may expand rapidly to include upper portions of the plant as it enters the reproductive stages, especially during periods of hot, dry weather that stresses plants and favors mite growth.
Effective mite management requires several elements – frequent inspection of fields, prudent use of insecticides and miticides, careful timing of applications, and thorough coverage with sprays. Treatment is recommended when a majority of plants are infested with expanding colonies on lower leaves and some mites can be seen migrating up into the midsection of the plant. Do not delay treatment. Infestations that become established throughout the canopy are difficult to control.
Most eggs survive chemical sprays, so a second treatment is usually required for large numbers of eggs, regardless of the kill rate achieved on adults and nymphs. Examine infested leaves on several plants under a hand lens every few days posttreatment to determine when most eggs have hatched. If active life stages appear to have survived the initial treatment, consider changing to a different miticide and altering application techniques to achieve better coverage. The goal should be to maintain functional leaves in the upper 2/3 of the canopy until the hard dough stage.
Please refer to the most recent version of the Sorghum Insect Management Guide for specific control recommendations.
Page last updated on 10/31/2013 by J.P. Michaud.