Newswise — In Spain, tomato growers are seeking effective ways to keep their crops weed-free as government regulation limits the use of formerly favored herbicides and plastics. Hand-weeding is not economically viable, and herbicides are limited to nine active ingredients that do not have the desired effect on some weeds. Therefore, mulching has become the weed control choice of many farmers.
An article in the journal Weed Technology reports results of a three-year test of 10 treatments for Spanish tomato crops. These included mulches of rice straw, barley straw, maize harvest residue, absinth wormwood plants, black biodegradable plastic, brown kraft paper, and black polyethylene, as well as herbicide, manual weeding, and an unweeded control. Polyethylene proved the best at weed control, but it is not necessarily the best choice because its use will likely be limited or prohibited for future European agriculture.
Farmers have favored the use of polyethylene mulch because it offers several advantages in addition to weed control, including low cost, more efficient water use, and higher yields and better quality of tomatoes. However, the plastic has a negative effect on the environment. After the tomato crop is mechanically picked, the plastic waste must be removed from the fields. This is particularly essential if the farmer wants to rotate crops, because spinach, for instance, will not tolerate any plastic residue.
Moving to mulches of biodegradable materials offers an appropriate compromise between weed control and care of the environment. Photodegradable plastics, organic polymer films made of starch, paper and harvest residues, and oxo-biodegradable materials are available alternatives, although the cost can be three to four times higher than polyethylene.
The present study found that the best alternatives to polyethylene were paper, biodegradable plastics, and rice straw. Absinth wormwood performed the worst. Paper was the only mulch that controlled purple nutsedge, one of the most abundant weed species found in the tomato fields. The application of paper as a mulch is a slower process and care must be taken to avoid tears, which adds to the initial cost of this mulch choice. However, cost savings occur in the end because the product biodegrades, eliminating removal and disposal efforts.
Full text of the article, “Effect of Biodegradable Mulch Materials on Weed Control in Processing Tomatoes” Weed Technology, Volume 24, No. 1, 2010, is available at http://www2.allenpress.com/pdf/wete-24-03-369-377.pdf
About Weed TechnologyWeed Technology presents (1) original research on weed/crop management systems, herbicides, weed resistance to herbicides, and weed biology; (2) reports of new weed problems, weed-related surveys, and new technologies for weed management; and (3) special articles emphasizing technology transfer to improve weed control. The journal is a publication of the Weed Science Society of America. To learn more about the society, please visit: http://www.wssa.net/.
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