July 19, 2005
To: Michigan Golf Courses
From: Michigan State University Turfgrass Faculty
Re: Golf Course Turf Conditions
Weather conditions in 2005 have been very challenging for managing turfgrass. The past winter resulted in numerous instances of winterkill throughout the state and the relatively cool spring slowed reestablishment efforts. The summer weather has been quite simply, brutal. Dew point temperatures have been in the mid and upper 60s to low 70s for extended periods. Precipitation deficits since April 1 range from approximately 2 inches in east central sections of the state to more than 8 inches in some areas of south western Lower Michigan . Although some drought relief has been provided by recent thunderstorm activity, thunderstorms have been widely scattered and precipitation amounts variable.
The weather conditions have caused severe turfgrass stress, and in some cases turfgrass death. Numerous turfgrass diseases including brown patch, Pythium blight, crown rotting anthracnose, and summer patch have been diagnosed. In some areas the disease pressure has certainly been more severe than what is typically experienced in Michigan .
Trees and Turf
Often some of the worst turf damage occurs on greens surrounded by trees and underbrush. Trees and underbrush restrict air movement in green complexes and result in higher temperatures and the inability of the plants to cool through transpiration. The lack of air movement in these areas often leads to greater incidence of turfgrass diseases, which of course can lead to turfgrass loss. Another factor that contributes to turfgrass thinning on greens, especially during periods of high temperature, is a lack of morning sun. A lack of morning sun on creeping bentgrass greens may be particularly devastating. The reason for turfgrass thinning is because the cool-season turfgrass plants grown in Michigan only photosynthesize (i.e. produces food) when temperatures are below 85 º F. Temperatures are normally below 85 º F in the morning during July and August. If the plants cannot photosynthesize due to lack of morning sunlight, they run out of energy, and eventually die. If greens on your course suffer turf loss this summer due to lack of morning sun or poor air movement and associated diseases, consideration should be given to removing or thinning trees and underbrush on the east and northeast side of greens to facilitate morning light and air movement.
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. In less droughty summers, frequent rains flush the salt out of the root zone so the salty irrigation water has minimal effects on the turf. During dry summers 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.
Irrigation Systems Tested
Unlike the summer of 2004 when abundant precipitation covered up any coverage problems in irrigation systems, the drought of 2005 is revealing every possible shortcoming in irrigation systems. In normal Michigan years older irrigation systems are adequate to keep turfgrass healthy due to periodic rainfalls that tend to keep soil moisture at more desirable levels. This summer, turfgrass is forced to rely solely on moisture from the irrigation system, which on some golf courses is older and often inefficient. Turf areas that show stress due to lack of irrigation coverage are most often edges of fairways, banks of greens, tees, and bunkers, and rough areas. In addition to the heat and drought stress, many of these areas are also high traffic areas that are subject to compaction.
As the summer progresses other pests may become problematic. Black turfgrass Ataenius may begin to cause damage in late July and early August. These small white grubs can damage fairways, tees, and greens. European chafer grubs may also cause damage later this summer. Dry weather conditions in the first two weeks of July favored European chafer survival. Japanese beetle grubs are also abundant in some places, they are more likely to be a problem in irrigated turf, like golf course fairways. If the drought continues expect grub damage in un-irrigated areas. Much of the visible damage that will be observed is from skunks, crows, or raccoons digging up the turf to find grubs. You may wonder why golf courses do not try to prevent grub problems. The simple answer is cost. Most golf courses cannot afford to preventatively treat large areas for grubs. At most, golf courses will treat the fairways and let the roughs fend for themselves.
As a result of all of the stresses and maladies the turf is suffering this summer, labor and pesticide costs may escalate as superintendents institute additional hand watering, fungicide and insecticide applications, and management practices to restore winter and summer damaged areas.
2005 is shaping up as one of the most challenging turf growing years in recent memory. Keep in mind that your golf course superintendent is doing the best job they can to counteract the challenges Mother Nature imposes in order to maintain a high quality playing surface for your golf course.
Dr. Kevin W. Frank and Dr. J. M. Vargas, Jr.