Web-based forecasts improve strawberry fungicide timing

08/01/2011 05:40:00 PM
Vicky Boyd

Meantime, Peres says she hopes more growers will familiarize themselves with the program.

Disease predictor passes the test

Grower Carl Grooms, owner of Fancy Farms in Plant City, Fla., has been testing Peres’ system and is impressed with what he’s seen so far.

In the past, Grooms often would spray automatically once a week. Now, if Peres indicates there’s a two-week window with no sign of disease on the horizon, he won’t spray. “We’re learning that maybe we don’t need to spray as much as we do,” he says. “This pinpoints the date of application more precisely.”

Grooms has set aside a portion of his 220 acres of strawberries as a test section where he follows Peres’ instructions precisely. For the rest of his acreage, he also factors in his 38 years of experience as a grower.

Grooms estimates that he sprayed about one-third fewer times when he followed Peres’ system. He says he would have wasted 10 fungicide applications this season if he had done it the old way.

So far, he says results have been the same in both areas, and the test section has used less fungicide and saved time and wear and tear on equipment.

Testing for resistance

At Clemson, Schnabel also has been testing Peres’ system with good preliminary results.

“The warning system looks just as good as the regular grower standard, but we’re using much fewer sprays,” he says.

But Schnabel’s main focus is on his own project.

“I’m interested in figuring out how we can incorporate more of those reduced-risk fungicides into our spray program without promoting resistance development in the gray mold fungus,” he says.

The fungus that causes molds is the “world champion in producing resistance,” he says. “It can really generate resistance to all chemical classes that we have available to us.”

By next season, he will have developed an assay that will tell in about two to three days if a chemical class is still effective against a fungus.

Researchers simply collect some strawberries with symptoms of gray mold, transfer the spores into test plates that contain a medium that will indicate if it is sensitive or resistant to a particular fungicide.

“If the fungus grows enough on the fungicide- amended medium after two days, then we know the fungus is resistant, and we shouldn’t continue to use that chemical class any longer,” Schnabel says. “We have to switch to something else.

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