New restrictions have been placed on an important crop protection tool used on more than 40 different California fruit, vegetable, tree and vine crops.
The California Department of Pesticide Regulation has ended a policy that allows growers in certain areas—also known as townships—to acquire necessary quantities of the soil fumigant 1,3-dichloropropene—sold under the trade name Telone—above an annual allocation cap.
The amount of Telone allowed to be used annually is based on potential exposure averaged over a 70-year span. DPR had allowed more to be used when requested, with the understanding that lesser amounts would subsequently be used so as not to exceed the averaged, 70-year limit.
The affected areas are largely in Fresno, Tulare, Merced, Monterey, Ventura and Santa Barbara counties. These areas have used more than the yearly limit of 90,250 pounds set for each township, which is 36 square miles. Some 450 townships in 42 counties use 1,3-D, with about 10 townships likely to be affected by the new policy, according to DPR.
Growers of crops such as sweet potatoes, almonds, walnuts, grapes and strawberries use 1,3-D as a preplant soil fumigant to give their ground a clean start and protect their crops against nematodes and diseases that result in lower yields and quality.
Fumigants continue to face tighter regulatory restrictions, leaving growers with fewer pest management options and less-effective materials. With the international phase-out of methyl bromide, growers have increasingly turned to alternatives such as 1,3-D, and they say the latest limits on the product erode their ability to produce their crops.
“Food costs are going to go up,” said David P. Souza, a sweet potato grower in Merced County, “because the less we produce, the more it’s going to cost. Hopefully, people are ready to adjust to that.”
DPR officials said they understand that no longer granting the exemptions will present challenges for farmers. But DPR Director Brian Leahy said the department “believes in being very protective when it comes to fumigants.”
“We continuously evaluate their use,” Leahy said, noting that DPR has been reviewing 1,3-D since 2009 to assess its toxicity and risk. The department said it expects to complete the study in 18 months.
Souza said in his township, the new limits will allow him to cover only about 20 percent of his acreage. He said Telone has always been used sparingly because of its limited availability, noting that he typically fumigates his sweet potato ground every other planting, rotating his ground into a grain crop for 18 months following harvest and won’t fumigate again until the third cycle.
David Doll, a University of California pomology farm advisor in Merced County, said the change in DPR policy has created a real bind for almond growers who had made planting decisions based on the belief that they would be able to fumigate with Telone.
“I think it caught a lot of people by surprise,” he said. “There were a lot of farmers who were expecting (the cap) to be raised and more Telone to be released, and when it wasn’t, I was getting one call after another from farmers who said they weren’t getting any Telone and they didn’t know what to do with regard to planting their almond orchard.”
He said he’s been advising almond farmers to treat what they can with the limited Telone, if they can get it, and then consider applying chloropicrin, which he said is less effective in managing nematodes but works well against Prunus replant disease. Other methods such as backhoeing are also not as effective, and he said he found no value in applying spot-steam treatment to almonds.
Doll said after seeing his own trial work, he consistently recommends fumigating before replanting.
“I’ve seen the stuff work. I’ve watched orchards developed with and without fumigants,” he said, noting that fumigated trees not only produce a crop earlier, but they have higher yields and also use water and nutrients more efficiently.
“If we have an efficient-running operation, we then can trim back our nitrogen, our water and maintain same or greater production,” Doll added.
Merced County farmer Bob Weimer, who grows sweet potatoes, almonds, walnuts and peaches, said the new policy on Telone comes at an especially difficult time when growers are already struggling with dwindling water supplies due to drought.
“If we’re hindered with disease issues underground attacking the roots, then the problems become exacerbated with a shortage of water,” he said.
Weimer said he has not had success growing sweet potatoes without fumigating the soil at some point. Last year, he planted without using fumigants.
“That was the biggest mistake I ever made,” he said. “Every potato in that field had wormholes in it. I can’t sell the product.”
He said growers’ inability to control pests and diseases wastes critical resources such as water, fertilizer and labor, and undermines the sustainability of the land.
By Ching Lee
credit: California Farm Bureau Federation