It is important for all growers to recognize the effects of plant competition in most of our crops. Plants used included vetches, clovers, yellow nutsedge, buckwheat, and centipede, bermuda and bahiagrass. The control plots were maintained weed-free by use of herbicides. After three years, trunk cross section areas, which started about 0.31 in2 increased to an average of 4.1 in2 for trees grown with crops around them compared to 7.7 in2 for trees with the weed free area. There were no differences in tree growth among the various crops used around the trees.
Weed control is one of the biggest challenges for organic growers.
There are several organically accepted herbicides, but they are non-selective and usually prohibitively expensive for commercial growers. We need to start working on crop rotations that can be used to reduce weed populations. Some have even used a glyphosate to kill tenacious weeds like Bermuda grass before they begin the organic certification process. Be sure to visit it if you can. Most of the 6 blackberry varieties have grown enough so that we can begin to apply mulches.