Become a junior forecaster

Many superintendents would argue, managing disease outbreaks due to weather is like managing people. Both are unpredictable and one must be reactive instead of proactive.

But by keeping a close eye on weather patterns and forecasts and weather and turf-related websites offered by research institutions around the country, superintendents can plan for and avoid outbreaks of the most common turf diseases. The majority of these tend to be fungus, which depends on moisture for survival.

Dr. Rick Latin at Purdue University in Indiana runs Turfcast, a website that helps turf managers in the lower Midwest keep a better eye on long-range forecasts, while Dr. Art DeGaetano at Cornell University runs Fore Cast, a website for superintendents and others involved in turf care around the Northeast, out of Cornell’s Atmospheric Sciences and Turf Team at the university’s Northeast Regional Climate Center.

Similar websites likely exist at universities in other regions of the country, but the experts urged superintendents to take a multi-pronged approach to managing outbreaks of dollar spot, brown patch and pythium blight. How can superintendents better manage disease by closely monitoring weather forecasts?

“It’s difficult to give you a short answer,” says Latin. “But these pathogenic fungi are active under certain types of environmental regimes,” says Latin. “We can define those based on temperature and moisture.”

The pathogen must be active and growing or there's no sense in applying fungicide, so one has to wait for the fungus to start growing before it can be killed quickly, he notes.

“The idea with the website is to identify those periods when the pathogens are growing,” Latin says. “Then we can schedule those fungicides most effectively and we can get more efficient control,”

The fungus doesn’t respond to the calendar, but it does respond to temperature and moisture. In Indiana in March, 2012, Latin says temperatures were well above 80 degrees for seven to 10 days, but in March of this year, temperatures never got above 40 degrees for the entire month. So the dollar spot pathogen was active in March 2012 but dormant in March this year.

So can one be proactive rather than reactive when it comes to something as fickle as the weather?

“Maybe we can improve our ability to forecast the weather, and if that’s the case, supers can respond to that,” Latin says.

“Supers can look at what’s ahead and, knowing how much they’ve sprayed already, they’ll know what to do. What we do at Turfcast is narrow that gray area between disease forecasting and scheduling application of fungicides,” he adds. “There’s a bit more certainty about a risk outbreak if you apply these models we have in Turfcast.”

DeGaetano studied meteorology at New Jersey’s Cook College at Rutgers University but for the last 15 years has been part of Cornell University’s Turf Team, studying the relationship between weather and disease outbreaks.

“People use our site for any number of things,” DeGaetano says. “One is irrigation: We have tools on the site that say should you be watering and how much water has evaporated from the turf and we also tie things to the forecast. If the forecast is for a good chance of rain, you may wish to hedge your bets there. We’ve done the same type of thing for different diseases and weed control.” DeGaetano notes that one model that gets quite a bit of use early in the season is the application for dandelions.

“You could be wasting your money throwing herbicide down on dandelions. By waiting until a later part of the season, you can get 80 or 90 or 100 percent kill on the dandelions,” he says.

Golf course supers and others in the turf care industry tend to do things by calendar.

“‘If it’s April 15, I need to do this,’ and that might be OK under average weather conditions, but that time to do something could change by weeks, whether it’s hot or cold or warm,” he says.

With Cornell’s Fore Cast, Northeast superintendents have more flexibility in their disease management program. Knowing when disease pressure could hit allows superintendents to be selective with applications.

“Instead of saying I have to put down fungicide every seven to 10 days, now, I can see a period of time where risk is going to be very high, so I might want to apply it sooner,” says DeGaetano. “Or if risk is going to be delayed for a few weeks, you might want to forgo an application.”

Superintendents always want to be aware of the weather and how it affects the turf, DeGaetano says.

“We had a period in July, in the 15 years I’ve been doing this, where disease was just off the charts, and we saw that in the models and we saw that in the reports we were getting from around the region,” DeGaetano says.

“It’s not only heat, but it’s heat and humidity that are the two most important factors, and this summer was filled with far more weather extremes,” he says.

In the meantime, Latin at Purdue says it’s his understanding that at some point in the near future there’s going to be a big improvement in forecasting methods for dollar spot.

Richard J. Skelly is a New Jersey-based writer and frequent GCI contributor.

Check it out…

The Turfcast site offers a wealth of data for superintendents in the lower Midwest to access and use in planning their applications of fungicides, insecticides and herbicides. Dr. Rick Latin and his associates at Purdue maintain the website and update it several times daily. It offers a daily summary of risk for dollar spot, pythium blight and brown patch.

“We use a variety of algorithms to assess the daily threat, and when threats accumulate over time, the site signals a high risk of disease outbreak,” says Latin.

With Cornell’s Fore Cast site, Dr. Art DeGaetano says: “The idea here is as a super you want to follow the weather but you don’t want to have to crunch numbers. That’s what our website is for. We take that data and translate it into the information a superintendent needs to help them make decisions about how much or whether to apply irrigation, fungicide or insecticide.”