Though weather this summer and fall wasn’t as bad as last year, we’ve still had our share of thin turf and fall events are taking their toll on the cool-season grasses. The perennial cause is the naturally shallow rooting of Kentucky bluegrass or perennial ryegrass at the same time that football and soccer seasons get into full swing in August and September. Additionally, the tremendous heat and humidity during July increased disease pressure and thinned or weakened perennial ryegrass in most sports fields. A less obvious cause is the heat and drought of August and September 2005. Many damaged and thinned turfs were heavily overseeded with perennial ryegrass last fall and/or invaded by annual bluegrass during the extremely moderate winter. Both of these species are extremely sensitive to heat and diseases, further adding to the thinning and damage of sports fields this fall. Lastly, annual bluegrass started germinating in mid-August this year because of the wet weather, filling in voids in the turf. Unfortunately, the shallow-rooted annual bluegrass does not hold up well to sports traffic.
There’s still time to help the field improve for next year and here’s what to do now:
- • Aggressive fertilization with a minimum of 1.0 lb N/1000 sq ft applied yet in October if no N has been applied yet in October and again in early to mid-November to maximize recovery on very thin turf.
• Overseeding now with perennial ryegrass will not germinate without turf covers or an unforeseen warm spell, so don’t bother seeding now.
• After the season is over, aggressively aerify, punching at least 20-40 holes/sq foot with the largest tines possible. Follow this with seeding Kentucky bluegrass at 2 lbs/1000 sq ft. This is a dormant seeding and it will germinate early next spring, so avoid herbicide applications next spring. Break up the plugs with your tool of choice and then apply urea or another soluble nitrogen source at 1 to 1.25 lbs N/1000 sq ft as listed in the first point.