Item could help strawberry growers meet requirements
By CECILIA PARSONS
For the Capital Press
California strawberry growers, who are losing some of their most valuable production tools to environmental regulations, have found a new tool to protect their crops.
An impermeable film is helping growers retain production while using alternative fumigants in their fields. It allows them to use less product, which cuts down on field emissions.
The impermeable film has five layers, two thin ethylene vinyl alcohol layers embedded in three layers of standard polyethylene film.
According to University of California researchers the "totally impenetrable film" traps fumigants in the soil for longer periods than standard film, increasing its effectiveness. UC researcher and weed scientist Steven Fennimore said more growers are adopting the new technology even though it can cost twice as much as standard film. The advanced film is made by Raven Industries in South Dakota.
"It definitely improves the efficiency of the product," said Fennimore in a phone interview.
The California strawberry industry, which produces 85 percent of the nation's strawberries, depends on soil fumigants to kill soil pests and weed seeds that affect yields. Since the 1960s, entire fields have been covered with film to hold fumigants.
Today, more than half of the state's strawberry acreage receives fumigant treatment via drip irrigation, but film is still needed to hold them in the ground. About 80 percent of California strawberry fields are treated with fumigants prior to planting.
Due to the phaseout of methyl bromide, growers have turned to alternatives, but face problems with emissions and stringent regulations. The most widely used fumigants, 1,3-D and chloropicrin, are classified as volatile organic compounds. Released into the air they react with nitrogen oxides and form ground-level ozone. Regulations cap total pounds of those fumigants used in areas of the state where air quality is severely impaired. Growers in the Ventura County area have been concerned they may lose the use of the alternate fumigants if the cap is reached.
UC researchers have been comparing the advanced film with standard film while using combinations of fumigants. The results, Fennimore said, 33 percent less 1,3-D plus chloropicrin is needed under the advanced film than standard films. They also found that fumigant concentrations were 46 to 54 percent higher. The higher concentration was also responsible for fruit yield and weed control similar to that achieved with methyl bromide.
The recent registration of methyl iodide as a soil fumigant in California requires the use of impermeable film.