|Rhizoctonia solani |
A "smoke-ring" of greyish-black myceiium from 1.5 to 4 cm wide develops around an active patch. Attacked grass leaves show dark-bordered lesions, become water-soaked and blackened, collapse, then dry up and become light brown with scierotia at plant bases. Patches 2 cm to 1 m in diameter may occur in short mown turf. It may progress very rapidly. Mainly in parts of eastern Canada and southern B.C., although a lower temperature form of the disease has been found in the Prairies.
- all grasses are affected, but some Agrostis cultivars are very susceptible
- hot, very humid daytime weather conditions with night temperatures about 18 degrees C
- unbalanced nitrogen applications leading to development of lush rapid growth
- frequent mowing renders fine turf more susceptible, as the fungus gains entry through wounds
Avoid unbalanced or excessive nitrogen applications particularly where there is a history of the disease. Reduce frequency of mowing. Reduce irrigation, especially late in the day during danger periods.
For information about other diseases that affect turf grasses, go to Major Diseases of Turf Grasses in Western Canada