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Home SportsNotes Brown patch disease caused by the fungus Rhizoctonia solani has been seen on tall fescue and perennial ryegrass turf this past week. This picture was taken 6/22/09 on 1-inch high perennial ryegrass and shows the circular ring and browning symptoms typically associated with this disease. These rings start off small but can be as large as 2 ft. in diameter.
Upon closer inspection, leaf lesions are tan or chocolate brown, with a dark brown band of discoloured leaf tissue where the necrotic tissue and the green tissue meet*. It is quite difficult to diagnose brown patch and it is often confused with dollar spot or pythium.
At 100 x magnification, the branching pattern of the fungal hyphae can be seen on the edges of the leaf blades.

Preventive fungicide applications are the most effective way to manage most turfgrass diseases. For brown patch make the application(s) when environmental conditions are favorable for the disease; when the night air temperatures do not fall below 65 F, day temperatures are in the 80s' - low 90s' F and there are wet conditions. Wet conditions from over watering or frequent rainfall is often the key element for severe disease outbreaks.

There are many fungicides labeled for managing brown patch. Some are: chlorothalonil (Daconil Ultrex), iprodione (Chipco 26019 or 26GT), flutolanil (ProStar), mancozeb (Fore), polyoxin D zinc salt (Endorse) the QoI (strobilurin) products (Compass®, Disarm®, Heritage®, Insignia®) are extremely effective against brown patch. Read the label for additional information for proper use of the product. If there is concern about other diseases read the label to see what diseases are controlled, for example the QoI (strobilurin) products are also effective for Pythium but not dollar spot.

Fungicides integrated with other management practices will maximize their effectiveness and management of the disease.

*Reference: Compendium of Turfgrass Diseases (3rd Ed., 2005) Smiley, R.W., Dernoden, P.H., and Clarke, B.B.

Posted by Joe Rimelspach