By Melissa Hansen
Stone fruit growers, especially cherry growers, have lost an important tool in preserving fruit quality with the recent voluntary cancellation of postharvest uses of the fungicide iprodione.
Rhone-Poulenc Ag Company notified the U.S. Environmental Protection Agency on March 18 of its plans to voluntarily cancel all postharvest uses on stone fruit crops from the Rovral label.
According to Danielle Larochelle, associate registration manager for Rhone-Poulenc and product manager for Rovral, this action was taken in response to EPA's concern with suspected carcinogenic risk from high exposure.
"EPA asked us to take risk reduction measures because of their concerns regarding the dietary intake of iprodione," said Larochelle, speaking from the company's headquarters in North Carolina.
Stone fruit label changes include:
--removing postharvest uses from the label;
--reducing the number of applications per season from 5 to 4; and
--extending the preharvest interval (PHI) from 0 to 7 days.
On grapes, the PHI also has been increased from 0 to 7 days.
Larochelle said that new labels were expected to be ready by mid-May. Existing inventory containing the old label may be used until stock is exhausted; those purchasing newly manufactured supplies of Rovral must follow the new label.
"This is a major issue for cherries," said Dr. Wally Ewart, vice president for scientific affairs for the Northwest Horticultural Council (NHC). "None of the other postharvest fungicides are as effective on cherries," he added. "Hopefully, most of the cherry growers already have this year's supply of material."
Unfortunately, said Ewart, chemical companies can take this type of action without first consulting with the affected industries. "Postharvest uses are the easiest to drop and the quickest way to reduce residues," noted the Pacific Northwest tree fruit industry representative.
Jeff Leonardini of Washington Fruit and Produce Company, Yakima, said "Without Rovral, we will have to change our preharvest strategies for pathogen control."
Because Rovral worked so well for the cherry industry as a broad spectrum postharvest fungicide, resistance wasn't a problem because different chemicals were used in the preharvest mix, he explained. "This really narrows down our options for preharvest programs due to resistance problems from most other fungicides. In the past, we saved Rovral for postharvest use only to prevent building resistance.
"There was such confidence in Rovral that in losing it, our level of anxiety and concern increases when that buyer opens a box," said Leonardini, who added that the ultimate goal is producing and delivering high quality fruit to the consumer.
The NHC will be coordinating with growers and industry organizations in the search for effective, alternative postharvest fungicides. Potential actions may include supporting registrations or pursuing Section 18 emergency use exemptions from EPA for a postharvest label for stone fruits of such materials as Rally (mycobutanil), Topsin (thifensulfuron-methyl), Botran (dicloran), Procure (imidazole), and Orbit (propiconazole).
