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. Michigan Golf Course Superintendents Association | www.migcsa.org
A Call From
Campus Summer Stress of Turfgrass Dr. Kevin W. Frank and Dr. J. M. Vargas, Jr. 2010 began as a stressful year for many golf courses that suffered winterkill injury; the summer has not been any easier for managing turf in Michigan. Precipitation patterns since June have been sporadic with many areas receiving excessive amounts of rainfall while others may actually be in a deficit. Grand Rapids recorded 8 inches of rainfall in June, 4 inches higher than average. In June higher than average rainfall was also reported in Detroit, Traverse City, and Gaylord. Much of this rainfall was from single events and despite the high monthly totals there have been turfgrass areas that are actually being stressed from lack of moisture. Rainfall in July has been closer to average but the combination of rainfall, high air temperature, and high relative humidity have been a perfect combination for enhanced disease activity and turfgrass decline. Irrigation Systems Tested 2009 was an extraordinary year when many golf course superintendents discussed how long they had gone before or between using their irrigation systems. Frequent rainfall and cool temperatures resulted in optimal turfgrass growing conditions. 2010 has been less consistent and inefficiencies in irrigation systems have been revealed on many courses. Turfgrass areas that reveal poor irrigation coverage first are typically edges of fairways, banks of greens, tees, and bunkers, and the rough. Many of these areas are also high traffic areas that are subject to compaction. Some of these trafficked, compacted, heat stressed areas may need to be reestablished this fall. In an effort to compensate for poor irrigation coverage and improve water management, hand watering has become commonplace on golf course putting greens. In a time when most budgets have been shrinking, superintendents may be challenged to add hand watering to an already stressed labor budget. Salty Irrigation Water Another problem that occurs on some golf courses during dry summers is the effect of high salt content in irrigation water. The high salt content makes it difficult to prevent turf wilting. Roots take up water by a process called osmosis. Osmosis works on the principal of there being a higher salt content in the root than the soil causing the water to flow into the plant. The higher the salt content in the soil the more difficult it becomes for the plant to take up water. If the salt concentrations become high enough in the soil solution, the water will not flow into the root. If salt content becomes really high, the water in the root will actually begin to flow out into the soil. In any event, it makes it difficult for the turfgrass plant to survive. If you’re been fortunate enough to receive adequate rainfall the rain will flush the salt out of the root zone so the salty irrigation water has minimal effect on the turf. If your course has not been receiving rainfall to flush the salts, when turf is irrigated with high salt content irrigation water it is important to flush the greens at least once a week to try to dilute the salt level in the soil. Golf courses should also consider switching to city water; either entirely or at least to dilute the salt content of the irrigation water. If you’re unsure about your irrigation water quality, conduct an irrigation water test so you know where you stand. Disease and insect problems High air temperatures combined with high relativity humidity and isolated heavy rainfall has resulted in some of the highest disease pressure we have seen on golf courses in several years. In June what started with nuisance fairy ring on fairways and greens has progressed to include anthracnose, summer patch, brown patch, Waitea patch and the sporadic case of Pythium blight. This year because of the high temperatures bacterial wilt has become a problem on many greens. There are two different bacterial pathogens involved one that is attacking annual bluegrass