State Agriculture Department officials have placed new restrictions on the pesticide methomyl after the chemical poisoned grape pickers this summer and growers fear the new rules could delay harvests in some vineyards.
The state now requires growers to wait 14 days before sending field hands into vineyards sprayed with the insecticide, sold under the brand names of Lannate and Nudrin. Earlier this spring the waiting period was only two days.
The tighter rules were prompted by two poisonings in vineyards this season. A crew of 53 grape pickers from the Jack Pandol & Sons Ranch in Delano was taken to Delano Regional Medical Center on Sept. 23 after one man passed out in a vineyard sprayed with methomyl and several others complained of pesticide poisoning symptoms.
All but one worker was released after giving blood samples to determine possible poisonings.
A majority of a 15-worker crew fell ill on May 25 while working in a methomyl-sprayed vineyard at Superior Farms near Delano.
Methoyml also was the culprit in an April 30 incident in which 17 farm laborers sought medical attention after entering a freshly sprayed orange grove on the Jobe-Howard Ranch in Lemon Cove.
High Levels Found
Jim Wells, a pesticide expert with the state Food and Agriculture Department, said high levels of methomyl residues have been found on the grape leaves but not on the fruit itself. State officials tested “eight or nine” vineyards treated with methomyl before imposing the new rules.
“We kept seeing fields that had been treated seven or eight days before our sampling that had residue levels higher than what we would have predicted,” Wells said.
Wells added the reported poisonings were surprising because the insecticide has been used for 20 years without any reported problems.
Growers can seek an exemption to the 14-day waiting period by having a private laboratory test leaf samples to determine if pesticide residues are within guidelines, Wells said.
After the Superior Farms poisonings the state extended the waiting period to seven days for girdling and other “cultural practices” such as thinning grape bunches and pulling leaves, Wells said. Girdling involves cutting into the bark around the base of vines to stop the flow of sap, which speeds ripening and boosts the size of grapes.
About 30 Fresno County growers have indicated they have used the pesticide in the last two weeks, said Jerry Prieto, deputy Fresno County agricultural commissioner. The delay could cut yields and cause problems with growers trying to reschedule their crews, he added.
The pesticide is used to kill a wide variety of insects. At this point in the growing season, valley grape growers are using it on leaf hoppers. State pesticide reports for 1986 show more than 854,000 pounds of the chemical was used on a wide variety of crops, from alfalfa to watermelons.