Use of certain new materials in the control of potato insects in Michigan

Summary

In the spraying and dusting experiments at the Lake City Experiment Station during 1947 insect infestation was not a serious problem. Most consistent control of potato insects in general was accomplished by applications of DDT in either sprays or dusts. Of the new materials used, Parathion 3422 as a dust was the most promising particularly in the control of the potato leafhoppers, whereas applications of 5 per cent DDT gave almost complete control of the six-spotted leafhoppers, flea beetles, and tarnished plant bugs. Benzene hexachloride, as a dust, ranked with DDT in the control of tarnished plant bugs and flea beetles. In the control of leafhoppers, however, benzene hexachloride in dust or spray combinations was not as effective as DDT. No late blight was present. There were no significant differences between materials in the control of early blight, because of the early killing frost.

As indicated in tables 1 and 2 where irrigation was used, an increase of insect populations was observed after six days in both the spray and dust plots. Insect counts were not correlated with yields of potatoes and the high yields of the untreated check plots can be attributed in great part to lack of serious insect infestations and diseases and also to the fact that the spraying and dusting equipment was not drawn through the rows where yields were taken.