You Are Here: Management Updates 2002 Archive July 1, 2002

Date: July 1, 2002
Category: Diseases
Subject: Disease Management in Lawns and Grounds

This turf disease message will be most useful for those working with lawns, grounds and other higher cut turf. Disease diagnosis is difficult in these situations because symptoms often do not match the pictures of golf courses in many disease books. If you combine the symptoms with the environmental conditions and some evidence of the pathogen (fungus), you are more likely to get an accurate diagnosis.

To see evidence of the pathogen (fungus), cut a small square of turf, moisten the leaves with a little water, and put it in a closed plastic bag with a moist paper towel. Make a tent of air over the surface of the turf. Place the bag where it will be the same temperature as the conditions of the turf- i.e. not in a hot truck or next to the air conditioner. By morning, you are likely to see growth of the fungus- mycelium (growing filaments) and spores. You can often see this same evidence of the fungus first thing in the morning when it's still dewy or on rainy days. They will disappear with mowing.

Clues to some common lawn diseases:

1) Dollar spot - 4-6" spots/patches, straw-colored leaf blades, individual leaf blades will have a lesion across the entire leaf, often with brownish red borders, low N turf, warm to hot weather, white cottony mycelium in morning or after a night in the plastic bag.

2) Pythium blight - mostly on ryegrass lawns, greasy, collapsed leaf blades, easily streaked by mowers, very hot and humid weather, high N turf, greasy leaf blades, white cottony mycelium.

3) Brown patch - most common on ryegrass lawns, usually large patches, individual leaf blades have irregular “bruised” looking spots, warm to hot and humid, high N turf, grayish white mycelium at leading edge of patch.

4) Red thread - may be in patches or scattered across lawn, cool to warm and humid weather, cool to warm and humid, tiny antler-like red threads growing off tips of leaf blades when dry, tiny pink puffs and gelatinous pink to salmon-colored fungus after incubation in plastic bag or in wet weather.

There are a number of other turf diseases, but these are the ones that produce the most abundant evidence of the pathogen when incubated in a plastic bag. Keep in mind that you will always get some fungal growth from dead and dying leaf blades. This may or may not be the cause of the problem. If you are still puzzled, please don’t hesitate to contact the UMass Turf Disease Diagnostic Lab with questions (413-545-3413) or if you need a diagnosis: http://www.umassturf.org/diagnostics/diseases.htm

- Submitted by: Dr. Gail Schumann