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May 28, 1972, Big Sandy, Texas

Research studies conducted in the Ambassador College garden suggest a simple, practical method for controlling the devastating effects of the Colorad' Potato Beetle without the use of noxious pesticides.

The study began in the spring of 1970 with the mulching of two rows of potatoes in the center of a two-acre patch. Prior to mulching, potato beetles invading the field had been dusted several times with a mixture of pyrethrum and Diatomaceous earth with very little lasting success. Within a short time after the two center rows were mulched with about two inches of chopped hay, they began to show an increased resistance to the beetles. Despite the dusting, the tops of the unmulched potatoes were totally devastated, but the mulched potatoes continued to thrive, no longer affected by the beetles and their larva. The mulched potatoes out produced the unmulched potatoes by 30%, even though they had also been damaged by the beetles before mulching.

The results of this test were repeated again in the spring of 1971 in the new garden area. This time, one-half the patch was mulched and the other half left unmulched.

How the mulch works to protect the potato plants (it also works on tomato plants) against the ravages of the Colorado Potato Beetle has not been elucidated, but soil temperature studies around mulched and unmulched plants indicate that soil temperature may play a part. The soil temperature around unmulched plants may go well above 105 on a warm, sunny day, whereas the soil temperature under a two-inch mulch may only go up to 85, The lowered soil temperatures and the reduced drying of the top soil provide a beneficial environment for the activity of many helpful soil microbes, plant roots and useful insects. Some of these soil microorganisms produce antibiotics, hormones, vitamins and other factors which, when absorbed by the plants, may also increase their natural resistance to certain insects and diseases.

Agricultural Research Department

Copyright 1972