Disease and insect control on potatoes in Ohio in 1950

Conclusions

The zinc ethylene bis dithiocarbamate formulations (Dithane and Parzate) under the conditions of these experiments gave better control of early and late blights, and higher yields, than were obtained with most of the copper-containing fungicides. The zinc dimethyl dithiocarbamate formulations (Zerlate, Methasan, and Zac) gave fair control of early blight but were comparatively ineffective against late blight.

In the presence of late blight the copper-containing materials gave better results than the zinc dimethyl dithiocarbamates, even though they did fall a little short of the results given by Dithane and Parzate.

A variety of fungicides and insecticides applied to potatoes in the “4X” concentration at the rate of 40 gallons per acre and at only 80 pounds pressure gave surprisingly good control of diseases and insects. This suggests that sprays more concentrated than those commonly used may come to be used on row crops when some of the obvious mechanical difficulties have been overcome.

One pound of actual DDT per acre applied at each application gave good control of flea beetles, leafhoppers, and Colorado potato beetles.

Parathion gave excellent control of both aphids and whiteflies.

In these 1950 experiments, DDT used at the rate of one pound of actual DDT per acre at each application, and applied under a rigid schedule in which the first application was made when the plants were not more than 3 or 4 inches high and repeated at 10-day intervals until the vines were dead, gave equally as good control of flea beetles as that obtained in previous years.