Field Evaluation of Resistance in Sorghums to Banks Grass Mite1

Abstract

The Banks grass mite, Oligonychus pratensis (Banks), is a serious pest of sorghum, Sorghum, bicolor (L.) Moench. Because of the unreliability of chemical control, mite resistant sorghums would be extremely valuable in controlling this pest. To determine levels of resistance in 19 sorghum lines and hybrids, field tests with natural mite infestations were conducted near Pecos, Tex. Evaluations were based on mite numbers, population density ratings, and damage ratings.Field evaluation of selected sorghum lines and F, hybrids indicated the presence of resistance to Banks grass mite. Grain type sorghums of similar maturity did not differ significantly in mite infestations, but some were damaged less than others; those with less damage were relatively high in sugar and were “non‐senescing” types. The two sorghums least infested were late maturing (SC 56‐14) or both late maturing and high in tillering (‘Sweet Sudan’). B Tx 618 was more resistant to damage than B Tx 378, and this resistance was reflected in hybrids between these lines and SC 599. Sorghums identified in this study should be useful in the development of mite resistant sorghum hybrids.