Blueberry Rust a Problem Throughout the Year for Florida Growers

Web AdminBlueberries, Disease

By Clint Thompson

One blueberry disease continues to surface to the top of concerns for Florida growers. Leaf rust is an ongoing problem that plagues production throughout the state, says Phil Harmon, professor and Extension plant pathologist at the University of Florida.

Blueberry leaf rust on the top of a leaf. Photo Credit: Philip Harmon, University of Florida/IFAS Extension.
Phil Harmon, professor and Extension plant pathologist at the University of Florida

“In evergreen production, rust has still been an issue. The dry weather has reduced it compared to last year. But with evergreen, we have leaves that stay on year-round, and that’s changed the game for us in leaf rust,” Harmon said. “Most of the growers that I’m hearing from these days are concerned about rust, particularly in evergreen. They are looking for new options and better ways to utilize the fungicide options that we have to control rust and prevent rust from coming in pre-harvest. It’s costing the plants carbohydrates and reducing their yields and the quality of berries being produced.”

Rust causes defoliation, and the leaves fall off at a time when blooms occur, the green fruit are set and are trying to fill out. If growers lose too many of their leaves during that process, the quality of the fruit suffers. Plants can also be stressed to the point where it causes more problems later on in the summer, post-harvest, and leads to other diseases like root rot.

“It’s a problem for us, both primary for production and also a problem for plant health going through the season,” Harmon said.

The disease’s presence during the year makes it difficult for growers to implement the fungicides that are available.

“At this point, we have a range in window of when the disease is active that is outstripping our ability financially and legally to use these products to prevent and really to control the disease,” Harmon said. “We’ve got a lot of good options. They’re expensive. We only have so many legal applications we can make of each of those.

“Our window is really wide through a long period of time in the fall, winter and through production of the year, when we’re needing to use them such as we don’t really have enough or can’t afford to make enough applications to prevent that rust on the leaves. It’s a concern for us. We really want to come up with better, more efficient ways to use the options that we have.”