The goal of this project is to evaluate the effectiveness of an organic pre-emergent compound, corn gluten meal (weed stop), in a vineyard situation. Following traditional mechanical post-emergent weed control or organic burn down product (burnout) in spring, banded application of corn gluten meal, was to be evaluated for its effectiveness at suppressing weed seed germination.
The study is being carries out on our vineyard consisting of one 17 acre and one 5 acre field planted in 25% French-American hybrid wine varieties and 75% European wine grape varieties.
Our cooperators, Dr. Nick Christian, Mark Chien, and Rich Tregidgo, all provided information important to successful completion to this project.
During the Spring of 2001 under row perennial weeds were removed by either mechanical hoeing (grape-hoe) or with a commercial, organic post-emergent burn down product (burnout). Within 7 days a commercial corn gluten meal (weed stop) was deposited in a banded application under the rows using a side dressing mulch spreader (Mill Creek Row Mulcher) at the prescribed rate of 20lb per 1,000 square feet. Corn gluten meal has been found to have a suppressive effect on seed germination.
The requirements for the efficacy of corn gluten meal include equitable, accurate application rate, the thoroughness in which it is worked into the upper soil, and the wetting in of the product. The Spring of 2001 was, unfortunately, one of the driest on record for our area. In addition the row mulcher proved an inaccurate method of applying the compound. Since we could not supply two of the requirements for the efficacious use of corn gluten meal we have decided to repeat the project this spring.
We will be using a more accurate spreader (Vicon) and now have the ability to water in a good portion of the study area. The use of Burn Out, will not be repeated. While the product does burn down emerged weeds, the cost of the product, the amount of liquid required for adequate coverage and the need for serial application to kill the weed limit its usefulness in our situation. The need to apply the corn gluten meal to bare ground and then work it into the soil in a timely manner indicates to us that mechanical weeding is the most effective and cost effective means.