Features Fruit Production
Spanish tomato growers seek better mulches

September 24, 2010 – 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.

September 24, 2010 – 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 craft 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, Issue 3, 2010, is available at http://www2.allenpress.com/pdf/wete-24-03-369-377.pdf.