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Homeowners Lawn Care Water Quality Almanac

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  May        Keep the Balance
Learn about the disease balance

What is disease?
Disease is the disruption of normal growth and appearance of a turfgrass plant owing to the interaction of the plant with a pathogen (usually a fungus). Pathogens are almost always present in the environment.

When does disease occur?
Disease occurs when environmental conditions favor the pathogen. Plants under stress are more susceptible to disease than unstressed plants.

What practices help the environment?

  • Provide adequate drainage. (Minimize low spots.)
  • Plant disease-resistant species or cultivars.
  • Avoid overfertilization. (Follow label directions.)
  • Reduce leaf wetness. (Water in early morning.)
  • Maintain adequate air movement. (Remove underbrush.)
  • Avoid watering in the evening.

How does disease affect water quality?

Disease can ultimately kill the grass plants, leaving bare soil that is more prone to runoff and erosion. Chemicals, if misapplied, can pollute runoff or leach into groundwater.

How can I reduce or prevent disease?

The best strategy is to promote a healthy, dense stand of turfgrass that can best cope with stress and thus resist disease pressures. By the time you see the disease it is likely too late to provide effective control. However, many disease-resistant cultivars can be planted to minimize future problems.

Healthy Turfgrass: Environment favors turfgrass



Diseased Turfgrass: Environment favors pathogen

The Eight Most Common Home Lawn Diseases
If you see symptoms of these diseases, you can confirm your diagnoses and explore options by contacting your local Cornell Cooperative Extension office, garden center, or lawn care provider. The Cornell Plant Disease Diagnostic Clinic web site, , is also helpful.

Brown Patch

Dollar Spot
Pythium Red Thread
Fairy Rings Leaf Spot
Rust Snow Mold

May is a good time for

Mowing: Keep up with the top growth, but do not remove more than one-third of the overall grass height with each mowing. This may require multiple mowings per week during periods of rapid growth.

Irrigating: Do not irrigate unless conditions are unusually dry.

Monitoring soil temperatures: For optimal preemergence crabgrass control do not apply materials until soil temperatures are between 55 and 59 F.  Materials applied earlier can lead to polluted runoff and wasted money because crabgrass does not germinate until soil temperatures, at 2 inches below the surface, are between 60 and 64 F.


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This page last updated on
November 05, 2000

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