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Off-colored, Thin, Open Turf

June 5, 2002

This spring, some turf does not look as good as would be expected, given the cool temperatures and abundant rainfall. Off-colored, thin, open turf seems to be relatively common throughout Illinois. How can these conditions be explained? Most likely, a combination of factors slowed turf growth and development.

First, some turf may be suffering from inadequate nitrogen due to excessive rainfall. When soils are wet, the nitrogen cycle may reverse--making available nitrogen unavailable due to denitrification. Thus, even though a turf may have been fertilized this spring, the nitrogen may not be available for plant use.

Another contributor might be the long periods of overcast skies. Lack of sunlight can affect turf photosynthesis and overall turf growth and appearance. Cooler-than-normal temperatures also reduced turf growth. After turf growth got off to a fast start with warm weather in mid-April, it slowed when air (as well as soil) temperatures cooled. Also, cool-season turf is flowering. Turf in flower becomes stemmy and open as flowering stalks develop and density declines.

Will these conditions persist? Probably not. For instance, as conditions dry, nitrogen in the system may become available. Sunnier, warmer days should en-hance turf growth, provided we ease into typical hot, dry summer conditions. When the spent, flowering shoots in the stand start to decompose--if weather conditions normalize–turf should regain the appearance we expect during late spring and early summer.

Unfortunately, a negative outcome of this weather may be reduced turf root development. When soils are waterlogged and soil oxygen limited, turf root growth may be restricted, which may manifest itself in the hotter, drier summer when turfgrasses with modest root systems develop problems related to a lack of available water. Throughout the season, an overall goal should be to use cultural practices that enhance root development and assist turf performance and sur-vival during unfavorable weather conditions. These practices include mowing high, applying balanced fertilizers, and aerifying appropriately.

Author: Tom Voigt


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