Effects of 2,4-D on Emergence and Seedling Growth of Range Grasses

Abstract

In a tarweed infested soil in the greenhouse, intermediate and crested wheatgrass and smooth brome seedlings growing with tarweed were sprayed with 2,4-D at 0.5, 1, 2, and 4 lb/A when seedlings had 1 to 2, 2 to 4, or 5 to 10 leaves. Tarweed was controlled at all rates. With simulated fall seedling, the higher the rate of 2,4-D and the younger the grass, the greater the injury to the grass. With simulated spring seeding, all rates of 2,4-D damaged the grass, but spraying at 0.5 or 1 lb/A of 2,4-D just after seeding resulted in the least damage. The field study indicated that .5 lb/A 2,4-D killed 90% of the tarweed; 1 lb/A killed 95% and 2 lb/A killed 99%. Rate of spraying had little effect on survival of the grass.