Expect the unexpected

Supplement - 2016 Spring Disease Guide

Successfully managing for unplanned outbreaks is an art form for any superintendent, especially when the bulk of the season’s disease program is purchased the previous fall.

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March 18, 2016

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Seasoned superintendents have a knack for anticipating problems and having a plan for dealing with them. When faced with an unexpected disease outbreak, a superintendent needs to know what steps to take.

And these “unexpected” outbreaks have been occurring more frequently over the past two decades or so. Admittedly the topic of climate change is a subject of strident debate in political circles, however, Dr. Jim Kerns, a plant pathologist at North Carolina State University, says those conversations should not detract from the reality of the situation.

“Regardless of what is causing the climate to change, it is changing,” he says. “Therefore, golf course superintendents should be monitoring weather very carefully if they want to win the battle against disease.”

Excessive heat and humidity are a recipe for turf problems, but management and cultural practices are contributing factors, as well, says SUNY Cobleskill turfgrass professor Dr. Alex Ellram. “Many cultural practices can contribute to disease outbreaks,” he says. “A few examples include nutrient deficiencies or excesses, especially with nitrogen. Other nutrients can certainly affect disease as well, but generally adequate but not excess nitrogen is key to minimizing many diseases.

“Stresses put on the turf with excessively low mowing heights, compaction from equipment, and damage to leaf tissue from sand topdressing and dragging also can create an environment favorable for disease,” Ellram says.

Overwatering – for example, in the event of unusual amounts of spring rain – can lead to increased disease pressures on golf course turf, Ellram says. “Excess soil moisture leads to inadequate soil oxygen that weakens turf and favors many pathogens like those that cause Pythium blight and brown patch,” he says. “One the other hand, keeping soil too dry can increase the incidence and severity of diseases like dollar spot and anthracnose.

“It is a generally accepted theory that the longer leaf tissue (grass blades) are wet, the more favorable it is to turf disease,” Ellram adds. “So irrigation should be done at times that promote more rapid drying of turf.”

It’s essential that a superintendent be proactive when dealing with a sudden outbreak, Kerns says. It’s important to make a complete assessment of the situation before determining how to deal with it, particularly if it’s an issue the superintendent hasn’t dealt with before.

“I suggest if the disease is not familiar to collect a sample for diagnosis immediately and send to a diagnostic lab,” Kerns says. “Then spray a broad spectrum fungicide coupled with a specific one. So if Pythium root rot develops, I always say spray Terrazole first followed by Segway while also protecting the foliage with something like chlorothalonil. Now this would be different depending on the disease. The key here, though, is to collect the sample before spraying the fungicide.”

Ellram at SUNY says it’s important that a superintendent have some product in reserve to deal with unpleasant surprises. “I suggest that when budgeting for fungicides, at least one if not two ‘rescue’ applications are included for the major diseases in your area,” he says. “That will allow rapid response without budget concerns. If possible, these rescue treatments will be ordered and available on site.”

There are instances in which a superintendent can justifiably skip a treatment because the outbreak itself will be short-lived, Ellram says. For example, a dollar-spot outbreak in December in Pennsylvania is not likely to be a long-term issue.

“However, if it is likely that conditions will persist for continued disease development, and your clientele are likely to notice the disease, treatment is generally justified,” he says.

If present trends continue, the number of surprise disease outbreaks will likely continue to rise. Ellram says it’s vital that superintendents be ready.

“As far as climate change goes, climatologists/meteorologists predict that more extreme events are likely in the near future,” he adds. “If this is true, turf managers need to be prepared for more frequent unusual weather events and the disease that may result from them.”