Plant growth and development and herbicide efficacy, part 1

In the 1920's and 30's field bindweed (Convovulus arvensis) was a major weed in the western US; so much so that coordinated research was undertaken by the most prestigious Agricultural Universities from California to Oklahoma to figure out what to do. And this was before the advent of herbicides, so scientists and farmers had to rely on other methods, especially cultivation. After much work, it was discovered that the pernicious bindweed could be eradicated from a field by regular cultivation for just two seasons. They used duck-foot cultivators; a collection of several flat triangular blades that overlapped and ran horizontally about 2-4 inches below the...