The talk turns to climate change, specifically global warming, and its impact on potential new turfgrass diseases. Could new maladies be on the horizon, the result of the planet getting a fever?

Joe Rimelspach, a turfgrass professor in the department of plant pathology at The Ohio State University, doesn’t have a specific answer. But Rimelspach knows one thing, “The environment has a tremendous impact on pathogen activity in turf,” he says.

There’s also a human element, which, ironically, is a sticking point in the global warming issue. Because golf course superintendents push turfgrass harder to appease golfers’ desire for faster conditions, there could also be more turf disease, especially when combined with hot or cold conditions, Rimelspach explains.

STORY HIGHLIGHTS

  • Intensely maintained turfgrass will continue to impact turf disease, from old diseases to new ones.
  • Fungicide manufacturers have introduced and will continue to introduce reduced-risk fungicides with low use rates.
  • Resistance management in disease control continues to be a challenge, although experts expect more fungicides to be released that have no known or little resistance.
  • Plant defense activators will continue to gain popularity in disease control.
  • If they perform, many superintendents will embrace biofungicides, although activity on that front is slow.

Much has been said to educate golfers to accept “lesser conditions,” but Rimelspach doesn’t expect golfer expectations at high-end clubs to subside, or even plateau.

The goods news is that fungicide manufacturers are keeping up with the turf diseases. They’re introducing products that not only perform, but are also safe for the environment and humans. And even if they’re more expensive than the fungicides before them, superintendents are finding that many of them are worth the price in the long run to control disease.

There are still challenges, however, such as resistance with fungicide groups. Sterol inhibitors, which inhibit development of cell walls in the target organism, and strobilurins, fall into this category.

“This is a great group of fungicides, but we have to be vigilant with them [to avoid resistance],” Rimelspach says.

On the horizon

It’s hard to predict what the future holds, but Frank Rossi, associate professor of turfgrass science at Cornell University, predicts a continued development of synthetic products with safer active ingredients (AI) that aren’t as resistant, as well as the development of fungicides with pigments for improved plant health. Rossi says he has spoken to many superintendents who want fungicides with low use rates that are classified as reduced risk. Rimelspach agrees, noting there will be fungicides with reduced-risk AIs that last longer, but they will also cost more.

But Rossi points out that some superintendents are sticking to their guns when it comes to disease control and using the products they’ve always used.

“We still have a fair amount of superintendents who do the same things they’ve always done because those things have always worked,” Rossi says. “Every profession is going to have that, whether you’re a teacher in grade school or you’re a superintendent.”

Bruce Clarke, director of the Rutgers Center for Turfgrass Science, probably would agree with Rossi’s take. But Clarke, who recently gave a presentation on turf disease control to a packed audience of superintendents, noted in his talk some of the effective new fungicides on the market, such as BASF’s Xzemplar, which controls dollar spot – curatively and preventively – on fairways, tees and greens. BASF built on its experience with boscalid, the AI in Emerald fungicide, to create Xzemplar.

Clarke also noted in the presentation that silicon-based materials have been shown to suppress diseases on edible crops, such as gray leaf spot on rice. Calcium silicate could make a solid tank mix partner with a reduced-rate fungicide for anthracnose suppression, he adds.

“On turf, we’ve been looking at it for a few years to control anthracnose,” Clarke says. “It appears calcium silicate does suppress anthracnose to a large extent.”

Both Clarke and Rossi say there’s increased interest in fungicides with copper-based pigments, which are known for their contributions toward plant health. That said, Clarke is bothered by how the fungicides are sometimes marketed.

As long as there’s intensely maintained turf, there will be turf disease.PHOTO COURTESY OF JOHN DEERE

“It peeves me when I see that 90 percent of the marketing in these products talks about their plant health properties,” Clarke says. “These are primarily fungicides … and darn good fungicides.”

Clarke provides some insight into how long it might take for some AIs to get to the golf market when he said he researched the AI fluazinam about 15 years ago. Syngenta released fluazinam under the product name Secure a few years ago. Fluazinam has no known resistance.

“It’s another contact fungicide that can be used in rotational programs,” Clarke notes.

Speaking of contact fungicides, AIs such as chlorothalonil, which have been vital to many superintendents’ turf disease programs, may continue to be restricted, but won’t be going away anytime soon, Rossi states.

“Chlorothalonil is widely used in a variety of products, from house paint to pesticides [and in products] to prevent mold and mildew,” he adds.

Rimelspach expects there could be more hybrid fungicides that combine synthetic and biological ingredients. Biofungicides alone, however, need to be studied separately from synthetics to see what kind of control they offer on their own.

“If they can reduce disease by 50 percent … that’s significant,” he adds.

If biofungicides have potential and aren’t harmful, the industry will embrace them, Rimelspach predicts. However, there hasn’t been much activity on the biofungicide front.

“We’ve seen some that have had potential, and we’ve seen some that were pure snake oil,” Rimelspach adds. “The industry would like to see more of them, but I don’t know that we will.”

Plant defense activators

Because he has spent plenty of time on Long Island in New York, Rossi says he has learned a lot about fungicides from a public perspective.

“People didn’t want golf courses spraying chemicals on Long Island,” Rossi says. “But they still have to spray something.”

Enter “plant defense activators,” which Rossi says have become a buzz phrase in the fungicide world. Rather than target a pest for control, plant defense activators help the plant defend itself against the pest. For example, turf treated with CIVITAS, a preventive fungicide, protects itself from damage caused by disease and insects.

Rossi believes progressive superintendents are implementing plant defense activators in their fungicide rotations and have found they don’t have to spray as often as they used to.

Clarke also touts plant defense activators, which he notes are in two categories – systemic acquired resistance (SAR) and induced systemic resistance (ISR).

“When you tank mix a plant defense activator with a synthetic fungicide, you’re getting the best of both worlds,” Clarke explains. “You’re relying on the plant to do its part, and you’re relying on the synthetic to provide additional levels of disease control.”

Clarke says plant defense activators must be used on a preventive basis.

“You have to turn on the genes of the plant before the infection starts,” he states. “You can’t use these products on a curative basis and expect to get a lot of additional control.”

Rossi says more superintendents want to implement “diversified disease management programs,” which include more than fungicides, to battle turf disease. Products in such programs include plant defense activators and cultural practices such as rolling. Rossi notes that Dr. Thomas Nikolai, Michigan State University turf professor, learned through research that rolling controls certain turf diseases, including dollar spot.

With any product, the bottom [line] for superintendents is cost and control, Rossi says.

“If [a product] controls disease and it’s cost effective, superintendents will use it, he adds.

COVER PHOTO BY HADELPRODUCTIONS/SIGNATURE/ISTOCK