Disease Watch 2016

It is impossible to know exactly what turf issues might raise their ugly heads this year. But being aware of what could happen gives superintendents a heads-up on what to look for on their course’s playing surfaces.

“In many areas in the northern United States, the fall was very mild, leading to increased rounds of golf,” says Kyle Miller, a senior technical specialist for BASF who covers the northern U.S. “However, this also means that the historical final fungicide applications occurred during a time when temperatures were warm, the turf was growing and product degradation was more extensive.” He adds the turf may have gone into winter in a more lush state, because temperatures remained somewhat elevated and the turf did not harden off as in most years. This could result in damaged turf next spring.

Summer patch has been a major issue the last two summers in the Mid-Atlantic, Transition Zone and Pacific Northwest, says Dr. Lane Tredway, Syngenta technical manager. Inoculum levels are likely still high, so disease pressure will likely continue to be high when the weather conditions are conducive to disease development.

In the Transition Zone and Southeast, spring dead spot may be a major issue this spring on Bermudagrass and zoysiagrass. “Prolonged warm temperatures this fall were likely conducive to pathogen growth and infection of roots, rhizomes and stolons,” Tredway says. “If this winter is unusually cold in the Southeast, as is predicted, spring dead spot symptoms could be very severe and widespread when the turf greens up in the spring.”

Last year’s weather was sporadic for most of the U.S., says Jenny McMorrow, a turf pathologist with Turf Diagnostic Inc. “For the first time ever, disease issues in my lab were more prevalent in September and October than July and August,” McMorrow says.

“Florida and Texas had periods of excessive rain and overcast conditions,” she adds. “The temperatures in these states are up and down and were not allowing for a normal dormancy. California has extreme drought. Late in the year in New York, the weather today was sunny with 60-degree temperatures, and that is unheard of in December.”

McMorrow reports incidences of spring dead spot much earlier in Florida and Texas, most likely due to the excessive rain and the “roller coaster” temperatures.

“We are grasping for solutions, as Rubigan is no longer on the market,” she says. “Before dormancy, spring dead spot control is important in the fall. However, careful monitoring of the Bermudagrass in the spring as dormancy breaks is just as important.”

She even developed a diagnosis for California called “salt-induced anaerobiosis,” because salt issues were affecting plant water management to the point where the right amount of oxygen was not able to remain in the soil.

“It became clear for many courses in California that unless several flushing rains occurred a decent root system will not be possible for some courses there,” she says. “Irrigating with effluent in this state may be necessary, but agronomically it is a nightmare.”

Rhizoctonia zeae also continues to be a “thorn in the side” of superintendents maintaining Bermudagrass, McMorrow says. “This disease seems to love situations whenever the Bermudagrass is weak,” she adds. “This can be when it is too hot, too cold, too wet, too dry, etc. I expect Rhizoctonia zeae to continue to wreak havoc on fungicide budgets in 2016.”

Weak in the spring

Summer 2015 was a strong disease season due to the amount of rainfall combined with hot, humid weather patterns, says Jim Goodrich, product manager of fungicides, insecticides and plant growth regulators for PBI-Gordon. In the Southeast, summer weather combined with a wet fall to create strong Pythium blight conditions. In addition, heavy precipitation (snow and rain) put superintendents on high alert for a potentially heavy snow mold season over the winter.

“What these conditions can lead to, if not managed properly, is the possibility for weak turf in the spring, which could lead to stress pathogens weakening the turf even more and allowing dollar spot and cool season brown patch to set in earlier than normal,” he says.

Disease pressure will always vary from region to region, as the factors (rain, humidity, heat) that lead to strong disease pressure are not always present in every region at the same time.

“However, at different times, as the weather present in one region pushes through into adjacent regions, the disease pressure can strengthen and weaken as the humidity and temperatures increase,” Goodrich adds.

“In 2015, Pythium was present in the Midwest on cool-season turf during the summer, but as the rains moved from west to east Pythium reared up in the Southeast and wreaked havoc on warm-season turf during the fall,” Goodrich says. “It doesn’t happen to this extent every year, but it is always a possibility if heavy rains and higher temperatures persist.”

If the El Nino weather patterns hold up, there will be a warmer than normal winter and regular rain will create excellent conditions for pink snow mold and yellow patch or cool-season brown patch, says Richard Buckley, director of the plant and diagnostic lab and nematode detection service at the Ralph Geiger Turfgrass Center of Rutgers University.

While difficult to predict, superintendents will see more dollar spot and red thread coming out of spring than normal, and perhaps even more anthracnose on greens.

“All of these diseases depend on tired and hungry turfgrass to manifest,” Buckley adds. “Extra stress late in the 2015 season may take its toll and that might show up as disease next spring.”

Disease pressure is dictated by the environmental conditions in a given season, says Dr. Jim Kerns, assistant professor and extension specialist of turfgrass pathology at North Carolina State University. Therefore, many areas of the country may experience wildly different disease pressures depending on what Mother Nature deals out.

“As usual, root diseases are most problematic during stressful periods, and it seems like these disease are ever increasing as we stretch the limits of playability,” Kerns says. “For example, in the Transition Zone, we saw a major increase in the incidence of summer patch on diagnostic samples we received.” Typically, this disease when observed on creeping bentgrass is usually isolated to areas with high pH or another cultural oddity. “This summer, however, we saw the disease in numerous areas throughout the Transition Zone,” Kerns adds.

A warm, wet spring could prove problematic because disease activity may occur prior to normal seasons, Kerns says. “Moreover, more fungicides may be needed to protect turf through the season,” he says. A warmer winter could aid with pathogen survival, and that in turn “may lead” to more disease in the spring and summer, “but again it depends on the spring.” He adds, “The worst-case scenario is a warm winter, followed by a warm, wet spring leading into a hot stressful summer.”

Aligning your defense

Winter weather patterns will say a lot about turf loss this coming spring.

“Whether you’re dealing with annual bluegrass or warm-season grasses, a harsh winter can be everyone’s enemy,” says Dr. John Kaminski, assistant professor of turfgrass science at Penn State University. “After that, it’s really about knowing your property and some of the chronic issues you’ve had in the past and manage those. It’s also important to know some other key diseases that could impact whatever species you’re managing, so that you can be prepared for those diseases that don’t usually hit every year. But when they do, you had better be prepared. “

Superintendents should conduct soil tests and adjust nutrient levels accordingly, as proper nutrition is one of the cornerstones of good agronomic practice.

“My old boss, Dr. Philip Halisky, used to say, ‘Disease is not the cause of poor turf; poor turf is the cause of disease,’” Buckley says. “If you are a good agronomist, then you don’t have to be a pathologist.”

Superintendents with turf species at risk for summer patch (annual bluegrass and Kentucky bluegrass; creeping bentgrass in the Transition Zone) should remember that disease development begins in the spring when soil temperatures reach 65 degrees Fahrenheit, Tredway says. Regular preventive applications beginning at this time are essential to thwart disease. Applications later in the summer, after significant root system damage has occurred, generally are not very effective.

Monitor and scout for diseases early in the year, so disease damage does not creep up and result in playing catch up from early on, Miller says. “After your third fairway mowing and second greens mowing, your fungicide program for the year should get started,” he adds.

Soil temperatures need to come up before grass starts to break dormancy and grow, Buckley says. “If you are wondering, take a plug and bring it into the shop,” he says. “Put it in a container or plastic bag with a moist paper towel for 24 hours. If the grass is healthy, it will pop and grow. It will be pretty obvious if there is a problem. Maybe then call your local turf diagnostician.”

Superintendents should see healthy, vibrant growth in both the shoots and roots, Kerns says. “Healthy turf is always the first line of defense against any disease,” he says. “Also, start fungicide programs based on soil temperatures not calendars or air temperatures. An early start usually equates to a non-stressful summer.”

Superintendents should evaluate their current control strategies.

“They probably already hit their early-order deadline, so it’s tough to actually save any money at this point,” Kaminski says. “They can, however, read up on the newer chemistries that are available and keep that in their minds moving into the season. Resistance is always a concern and there may be some newer chemistries out there to help in their rotations.”