A Test of Thiram on Two Rabbit-Infested Areas of Oregon

Animals seriously reduce survival and growth of plantations of nursery-grown stock in some areas, thus reducing productivity of land for timber crops. Two such areas in Oregon were planted with Thiram-treated Douglas-fir seedlings. On one of the plots the snowshoe hare (Lepus americanus) was being studied, and on the other the brush-rabbit (Sylvilagus bachmanii). Populations had been estimated already, so we could observe the degree of repellency of Thiram against a known density of animals.1 These study areas were representative of conditions that sometimes result from the standard method for harvesting coniferous forests, especially Douglas-fir, in western Oregon: clear cutting with subsequent slash burning. Natural regeneration usually develops satisfactorily on such areas, but erratic crops of seed, unwanted fires, and adverse weather may make planting necessary. Often these clear-cut areas are large and in time become "hardship" areas that develop extensive patches of brush suitable as habitat for some species of wildlife. Various ways to protect seedlings against these animals have been devised. Mechanical protection by animal-proof fences or screens around individual trees is limited by cost. Cultural controls, such as changing the habitat by reducing or eliminating weeds and brush to make an area inhospitable, are a possibility and should be investigated more thoroughly. Plant systemics show promise, but their danger to game animals has not been eliminated.

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Author(s): Edward F. Hooven

Publication: Tree Planters' Notes - Issue 79 (1966)