COURSE CARE
Warmer Weather Will Come Soon April 30, 2013 By Darin S. Bevard

Cool-season brown patch has been discussed frequently with the combination of cool, wet and cloudy weather that has been experienced in much of the region. With warmer temperatures, the symptoms of cool-season brown patch will subside, but brown ring patch will become more of a problem.

Surprisingly, the spring of 2013 feels a lot like the winter of 2011/2012 in a bizarre sort of way. Remember the late fall and early winter in 2011? We experienced mild temperatures for the duration of that time period that persisted into the spring. The common comment at the time was, “Just wait until the other shoe drops, and the cold weather really comes.” In other words, everyone felt that we would eventually experience payback for the mild winter weather. We never did. Now fast forward to today. We keep saying that warmer weather will come soon, and it certainly will, but in the meantime we are getting many questions regarding the impact of persistent colder temperatures on turf growth.

We learned last spring that it was important to be patient with nitrogen fertilizer practices. The temptation to apply additional granular fertilizers beyond your normal spring programs can be hard to resist when the grass is not growing as a result of cold temperatures. Growth rate of the turf will not accelerate greatly until soil temperatures are consistently over 60 degree F. Applying extra fertilizer now may lead to excessive growth when the fertilizer releases with warmer weather. In conjunction with natural nitrification, clipping yields can be difficult to control, and increased mowing frequency and/or increased growth regulator applications will be necessary. If you feel you must apply additional nitrogen to the turf, spoonfeeding applications through the sprayer are a good option until temperatures increase and turfgrass response can be evaluated. Growth rate of the grass will increase in the near future as soil temperatures also increase.

Reports of cool-season brown patch (Rhizoctonia cerealis) and brown ring patch (Waitea circinata; var. circinata) have increased in the past week. The appearance of these diseases is very similar, but the environmental conditions for their occurrence can vary. Cool-season brown patch is more common under the current cool, wet weather patterns. Generally, the symptoms of this disease are more of an aesthetic issue than anything. Playability generally is not affected, and when warmer, drier conditions occur, the grass will grow out of the symptoms. Fungicide treatments may be necessary to suppress symptoms if weather conditions continue to favor development of cool-season brown patch, especially where Poa annua is an important component of putting green turf. Brown ring patch (also known as Waitea patch) activity is also beginning, and as the spring progresses, warmer temperatures will favor increased disease activity. Brown ring patch can be more damaging to Poa annua than cool-season brown patch. It is important to be aware of the difference in environmental conditions that favor each of these diseases. Cool-season brown patch will be most active at temperatures up to 65 degrees F while brown ring patch will become more of a problem at temperatures from 75 to 85 degrees F, although it can occur at lower temperatures as well. Fungicide treatments are often needed to prevent damage from this disease, especially as temperatures increase. Call us if you have specific questions for treatment of these diseases.

Finally, Poa annua seedhead production is at its peak in many parts of the region, and playability is being affected. If large quantities of Poa annua seedheads have emerged on greens at your golf course, additional growth regulator applications for seedhead control will not help with this problem. The best option is to lightly groom the greens to mechanically remove the seedheads for improved playability, but do not be so aggressive that you compromise the health of the grass. The flowering period of Poa annua will subside toward the middle of May, and playability will improve quickly.

The weather will get warmer soon. Whether or not we receive “payback” this summer with higher than normal temperatures remains to be seen. Perhaps cooler weather patterns will stay in place. The only thing for sure is that maintenance programs must be adapted to the weather, because the weather will not adapt to us.

We would also like to remind all TAS subscribers that the deadline is approaching for the discounted TAS fees. To receive the $500 discount, payment must be received by May 15, 2013.

Source: Darin Bevard (dbevard@usga.org)

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