Each one of these alternatives work, but often are very time consuming, expensive, and are carried out, usually, by people intentionally trying to avoid the use of synthetic pesticides. Most producers opt for the simpler, and often, lower over-all impact on the environment, use of herbicides to reduce weeds under the trees. Where cover crop or weeds grow, the bulk of tree roots form in the second and third foot of soil. If competition is reduced, the trees form the highest percentage of their roots in the much more biologically active first two feet of soil depth. In areas with poor quality soils, the orchardist should not give the best foot of soil to the weeds.
Weeds can greatly out-compete the trees for nutrients, especially nitrogen.
This complicates the growers attempts to create an efficient nutrient balance in the trees, as it is never certain from one application to the next what percentage of the applied nutrient will enter the trees, or when it will get there. Trying to compensate for weed growth by applying higher rates of nitrogen fertilizer may increase the nutrient in the tree, but more often leads to greatly increased weed growth. Perhaps even more important, weeds block the sprinkler pattern, which may greatly decrease the efficiency of water application. Weeds also have the aggravating ability to lean over and tangle the mechanisms of sprinkler heads, preventing their rotation. During snowy winters, they sometimes chew the bark off of the lower portions of trunks, especially on younger trees.