Nature struck back againthis time at weed-killing 2,4-D. Last week the Department of Agriculture glumly admitted that Johnson grass is showing signs of making itself immune to 2,4-D.
Johnson grass, originally and recklessly introduced as a forage crop, is a pest in much of the South, especially in cane fields. Its perennial rootstocks can be clawed up through cultivation, but the pesky seeds keep blowing into cultivated fields from a distance.
In theory, 2,4-D is supposed to kill only broad-leaved plants, not grasses, but Department of Agriculture men at Houma, La. found that when the potent chemical was applied directly to the soil...