Agriculture Reference
In-Depth Information
liage, flowers, and developing fruit on fruit trees and bushes, but they should
be safe to use in an orchard, given careful application.
Their greatest value would appear to be as spot treatments within tree
and “sandwich” rows. At least one citrus oil product now approved for organ-
ic use also contains a soap or surfactant component similar to the herbicidal
soaps described in this section. Surfactants help herbicides and other pesti-
cides cover and stick to plant surfaces and can make some contact herbi-
cides more effective.
Clove Oil
Clove oil (eugenol) is found in several commercially available products, at
least one of which is registered with OMRI. In some cases, the clove oil
is blended with vinegar and other ingredients to increase the herbicidal
activity. While these products show promise for ornamental landscape and
garden use, more testing is needed to determine how well they work in com-
mercial orchards.
Corn Gluten Meal
Corn gluten meal is a by-product of the wet milling process for corn. It was
originally patented and introduced by Iowa State University as a natural
herbicide in 1991. According to the developers, corn gluten works when ap-
plied before weed seeds germinate, when it can inhibit the root formation of
germinating plants. Unfortunately, after 2 years of trials in Oregon, research-
ers concluded that corn gluten meal did not control any of the weeds under
any circumstances. It would appear that, for organic fruit growers, corn glu-
ten might best be used as a fertilizer rather than an herbicide. It has a fertil-
izer analysis of 9-0-0. OMRI presently lists two corn gluten products, one of
which is advertised as a fertilizer and soil amendment.
Herbicidal Soaps
Several herbicidal soap products are sold for use in North America. The ma-
terials are quite similar to insecticidal soaps that have been used for many
