Terry Mize

Insecticides applied at planting time or as foliar sprays to control chinch bugs on grain sorghum

In recent years large areas of the sorghum crop in central and eastern Kansas have been damaged repeatedly by chinch bugs. The outbreak was more severe than at any time since the 1930s and overwintering numbers (as counted in the spring of 1981) were higher than at any time in recorded history. Research has been underway since the mid-1970s to identify ways of preventing or reducing damage. One approach has been to apply systemic insecticides to sorghum or corn at planting time to provide protection to the emerging seedl ing. The most promising method in that approach has been to apply granular carbofuran (Furadan) infurrow. With adequate soil moisture, it has protected the seedling plants about 3 weeks. Another approach has been to use rescue treatments by applying insecticides as foliar sprays directed toward the base of the plants where the bugs are congregated. In previous studies we have obtained an excellent degree of knockdown with carba-ryl (Sevin) or carbofuran (Furadan) applied in this manner. Observations and data do indicate, however, that most foliar applied insecticides have a relatively short period of residual performance and must be applied frequently under conditions of reinfestation. In 1981 we continued our studies on both plantingtime and foliar treatments using both labeled and experimental nonlabeled compounds. Results for 1981 are presented here.

Chinch bug resistance in commercial grain and forage sorghum hybrids

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