Land Clearing by Power Methods in the Control of White Pine Blister Rust

Abstract

To eradicate wild currants and gooseberries for the control of white pine blister rust, it has been necessary on some alluvial bottom lands, where these bushes grow in dense concentration tangled with willows and other species, to clear the area completely of all brush by the use of the so-called bulldozer. The bulldozer is a tractor of the caterpillar type and is similar to the machine used in road construction, with the exception that the solid blade used for moving dirt is replaced with a heavily constructed frame holding a series of digging teeth (Plate 12-A). The frame or brush rake was specially designed by the Division of Plant Disease Control of the Bureau of Entomology and Plant Quarantine, U. S. Department of Agriculture, for clearing brush and Ribes from stream bottoms. In use the teeth in this special blade are set to penetrate 3-4 inches into the ground, or deep enough to catch the roots. The brush rake can be raised or lowered as the machine moves over the ground. As the bulldozer moves ahead, the brush is collected in front of the rake and is pushed into a pile or windrow. The brush piles are burned in the fall or in the following spring. After the brush is burned, the area is planted to grass. Many of the areas cleared by the bulldozer have been converted into