With the growing season dwindling and the arrival of cooler weather, a few cases of Rhizoctonia zeae have been observed on recent USGA Turfgrass Advisory Service visits. Early to mid-September is a prime time to see Rhizoctonia zeae or Mini Ring as some call it. The recent weeks of cooler, cloudy weather from tropical storm Lee and Hurricane Irene probably did not help, either.
The good news is that these small rings won’t cause any major turf damage. The impact is mainly visual, but they can linger all during fall without fungicide treatment. A simple rotation every 14 days of both a systemic and contact fungicides can provide some relief of the symptoms, but is important to get the products into the lower leaf canopy near the crown where the fungus resides. Immediate irrigation after the fungicide is applied is the key to place these plant protectants where they are needed, even with the presence of a contact fungicide in the rotation. Do not let the fungicides dry on the leaf tissue after the application prior to irrigation. This is not an easy target to hit and precision application techniques are vital.
Besides the fungicide treatments, applying small doses of nitrogen fertilizer to maintain new leaf tissue growth is helpful. Feed the plant and keep it growing so it can produce new tissue.
If anyone would like additional information on the curative fungicide program for Rhizoctonia zeae, simply send us an email and we will be happy to respond back with this information.
Source: Patrick O'Brien 770-229-8125 or patobrien@usga.org and Chris Hartwiger 205-444-5079 or chartwiger@usga.org