One of the enjoyable things about writing for TechNotes-SH is the part where I try to convey some of the turf conditions in the United States. Depending on how you look at it either I am 6 months ahead or 6 months behind South Africa. Hopefully the observations I make may help you as the coming summer season approaches.
For most of the United States is has been extremely hot and dry this past May and June. Drought is always an issue, but this year the middle part of the United States has faced particularly dry conditions. However we have faced brief but extremely severe storms. If you watched or read about the third round of the PGA tour event the AT & T National (Tiger eventually won) the course was closed on Saturday to spectators because of power outages and fallen trees due to something called a "Derecho".
I had never heard of a derecho until that tournament. For those who may not know what a derecho is it is a relatively long-lived straight line wind storm that sweeps over an area at high speeds (hurricane/typhoon wind speeds).
With the weather extremes this summer the turf as suffered. Currently one of the more difficult diagnostic challenges is determining if the turf is suffering heat/drought injury, billbug damage or dollar spot. In all three cases the turf appears brown. Given how dry it is you would expect dollar spot not to be such a problem but the occasional storm and spike in relative humidity can quickly bring on a devastating outbreak of dollar spot even on couchgrass. Dollar spot can be diagnosed by looking at the leaf symptoms that appear as a bleached out lesion that is constricted with a brown ban on the outer edge of the lesion.
Billbug injury symptoms look almost exactly like drought injury. To check for billbug pull on the brown leaves and if they are easily removed, look to see if the plants have been chewed off at the base. This is a good sign it is billbug damage. Another sign is when adequate precipitation returns and the turf greens-up, those areas that don't are most likely damaged by billbugs or another insect.
Watering, as many of you know is a critical practice during drought periods (matter of fact proper watering is important under any condition). In an attempt to keep turf firm light frequent watering is commonly practiced, but the downside is the turf is battling to stay up with daily evapotranspiration rates, and even in low salt soil or water conditions, the turf begins to accumulate dust, salt, minerals, etc. especially in sand rootzones that can impact water movement. An occasional deep watering is needed to move these materials out of the top couple of centimeters of the rootzone.
In the next issue I will continue with some of my observations. Some of you may wonder where the title for this issue came from. I was influenced by the Hunter Thompson book, "Fear and Loathing in Las Vegas".
Karl Danneberger, Ph.D.