What is in this article?:
- Rainy, cool spring may create 'perfect storm' for strawberries
- Other options effective
• Growers may think they are controlling gray mold with weekly sprays, but in reality it is the relatively dry weather that prevented the pathogen from taking off.
• Resistance has built up to such levels that the use of some chemicals is no longer justifiable.
Other options effective
But Schnabel also says growers still have sufficient options for effective disease control. “The good news is that a sufficient number of chemical classes that — if rotated correctly — should allow for reliable disease control,” he said.
The goal for Schnabel, who is part of a regional strawberry research project headed by the University of Florida, is to make growers aware of the problem and to get them on board for a regional resistance-monitoring program.
“We are in the process of offering to growers in South Carolina, Georgia, North Carolina and Florida a service that will give them the information they need to make science-based decision about spraying and keeping it effective.”
Schnabel’s research group collected samples taken from four counties in North Carolina and from eight counties in South Carolina.
“We found resistance to certain chemical classes in all of the sampled areas,” he said. “Resistance is based on point mutations in the fungicide target genes, which really is the worst possible kind of resistance. That means even an increase of the dose will not matter.”
Schnabel received $850,000 from the four-year, $2.9 million USDA National Institute of Food and Agriculture grant that supports efforts to forecast outbreaks of two fungal diseases threatening the nation’s $2.1 billion strawberry crop.
Managing emerging fungicide resistance in strawberries is just one aspect of the proposed research. With the help of a disease forecast system to predict high risk of infection by analyzing air temperature and leaf wetness, the number of total applications can be drastically reduced, said University of Florida plant pathologist Natália Peres, the regional project leader.
Experiments so far have shown that growers can potentially reduce fungicide use by half without compromising disease control.
The grant will enable the team to test the system in other strawberry-producing states, including South Carolina, with the added component of monitoring fungicide resistance and advise growers of alternative fungicide options.