Rotary hoeing also helps place the herbicide in the upper soil surface so that when rains do fall, the herbicide is in a better position to be quickly taken up by weed seedlings and hopefully kill them. If it has not rained within seven days of the first rotary hoeing, make a second ass with the rotary hoe to kill the next generation of weeds. These treatments work best when weeds are actively growing. When weeds are stressed by lack of adequate soil moisture, chemical control declines. If you decide to apply post-emergence herbicides under very dry conditions, be aware that crop injury may occur and weed control will be poor.
Some growers mistakenly believe that soil loses more moisture when cultivated.
So it is always a wise decision to cultivate weeds early on. This way, the weeds in the row can be covered with minimal effect on the crop. A second cultivation can be done when the crop is 14 to 18 inches tall. This requires timely mechanical practices, but keep in mind that in drought years, a few uncontrolled weeds cost more in reduced yield than in years with ample moisture.