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Weather Update
The summer solstice arrives today, so enjoy the longest day of the year (it certainly isn’t the hottest!!).
We did have our second round of 90 degree weather this past week, the first heat we have seen since May 15-16.
Relative humidity was high early in the week, which brought out a few fungal diseases, but the RH fell sharply later on through the weekend and into Monday (6/18).
Dry areas on greens and fairways started to show heat stress and wilting, which brought out the hand hoses and syringe cycles.
If you are developing any localized dry spots, the symptoms may have been showing by Monday as well.
Cool weather and showers have returned to the area yesterday and this morning, so the stress should be off, and any injured areas will have a chance to recover.
The forecast is for cool to moderate temperatures for the next few days, with overnight lows back in the 50s and daytime highs staying well below 90 F (at least in the North!)
Diseases
The heat and humidity that rolled through should have put an end to activity of Microdochium patch and other cool weather organisms.
Dollar spot became active once again last week, the first major outbreak since mid May.
Also, some unusual brown patch type symptoms (subliminal?) that may be caused by a type of Rhizoctonia solani were observed, as well as some yellow rings on Poa caused by Rhizoctonia zeae.
The yellow ring symptom is an interesting occurrence, since it is not a solid patch and does not affect bentgrass.
Sometimes you will see broken rings or part circles where bentgrass clones interrupt the progression of the fungus through the Poa.
Also, the Poa is usually not killed, but only turns yellow and may recover quickly if there is a change in the weather.
With the first heat and drying days of early June, take-all patch on bentgrass will become evident, and there have been reports of symptoms from courses where the disease occurs frequently (annually).
Symptoms of take-all include a yellowing and stunting of bentgrass in a fairly distinctive circle (usually about the size of a salad plate - 4 to 8 inches in diameter at first).
Under severe water stress, the patches can wilt suddenly and turn reddish brown.
Any clumps of Poa or ryegrass in the patch will be unaffected.
Older (perennial) patches of take-all disease may be up to 2 feet in diameter or bigger, and may have weeds or some bentgrass recovery in the center of the patch.
On another note: many superintendents are reporting very shallow rooting of turf on greens (esp. Poa annua) and in some cases on fairways.
Apparently the harsh early winter we had followed by the cloudy cool spring has limited turf rooting.
Areas that are prone to take-all or summer patch may be severely affected if weather patterns favor disease development, since many plants have limited rooting to begin with.
Also, any hot and dry days like we had earlier this week will cause plants to rapidly stress out because of the shallow, weak root system.
Insects
Cutworm activity has been reported for the last week or two from central Illinois, but no major infestations are reported.
For the Chicago area, there have been very few reports of any insect problems so far, perhaps due to the mostly cool weather of recent weeks.
There was a report of some Ataenius grub damage on a fairway from the south side of Chicago, so it is likely these buggers are lurking.
Dr. Ray Cloyd reports in the June 20 issue of the U of I Home, Yard and Garden newsletter that there are large numbers of adult moths of both cutworms and armyworms being observed, so there will be egg laying and the appearance of larvae in the next couple of weeks.
It is likely that we will see significantly more damage from cutworms and other lepidopterous larvae soon enough!
(See also U of I turf tip from y2k.)
The newsletter also contains a good summary of Japanese Beetle problems by Phil Nixon, who points out that emergence of adults will begin soon in central Illinois followed a week or so later in northern IL (around July 4).
Weeds
Poa annua continues to set seed off and on, depending on swings in temperature (?).
Some seedhead suppression was observed by utilizing Embark, Proxy, or AquaGro, but the results were much more variable than last year.
Embark continues to show phytotoxicity to bentgrass at green height.
A single application of Proxy + Primo (5 fl oz + 1/8 fl oz per 1000 sq ft) gave pretty consistent suppression at all test sites in the western suburbs for 3 to 4 weeks.
Multiple applications of Proxy (alone or plus Primo) also appear to have considerable phytotoxic side effects (primarily yellowing and thinning).
The correct timing of pgrs for best seedhead suppression remains a mystery; hopefully data collected this year will lead to an improved understanding of the influence of air and soil temps on seed set.
If we could get a better handle on application timing, maybe lower rates could be used and thus reduce the potential for phytotoxicity.
Much more information should be coming along on this topic as the season progresses.
Be sure to check out the U of I TURF website for more information, turf tips etc. and the U of I Home, Yard and Garden newsletter.
Please respond with your observations to newsletter@interactiveturf.com.
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