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Weather Update
The extreme heat and humidity came to an end finally about 10 days ago (Aug 12).
This summer was not a record setter by any means, but much warmer and more humid than normal.
In the Chicago area, we have had about 20 days with the daily high temperature reaching 90 F or above, and 43 days of 85 F or above (May 15 to Aug 22 = 100 days total).
In central Illinois, there were roughly 35 days of 90 F or above for daily high temps, and 60 days of 85 F or above (60% of total!).
Yes the lads in central Illinois have it much tougher than those of us north of I-80...
Unfortunately, a great deal of damage was done to fine turf areas this summer, especially turfs containing the heat sensitive Poa species (P. annua and P. trivialis).
Decline of Poa wasn’t due strictly to the heat, either. In some cases, dry conditions combined with traffic patterns and other factors to weaken the turf, while in other situations it was too much water and subsequent heating that killed the grass.
Many superintendents noted that the Poa was unusually shallow rooted coming out of last winter and for most of this spring, and this lack of roots probably set the turf up for injury from our hot and humid summer.
The last week to ten days has been much cooler, especially in northern Illinois.
Soil temperatures have dropped by at least 15 degrees, and injured Poa is showing signs of recovery from the stress.
Also, areas that were killed outright and were subsequently overseeded now have rows of new green seedlings showing.
Many superintendents took advantage of the chance to turn a negative into a positive by slit seeding bentgrass into areas of Poa annua that were killed from heat stress (dry) or scalding ("wet wilt").
Hopefully the weather will remain more moderate for the next few weeks heading into autumn, and heat damaged turf will recover fully and give the golfers some healthy turf to play on before the snow flies (and the snow birds fly south!)...
Diseases
There is still quite a bit of an "overhang" of disease problems left from the hot and humid summer. We are getting quite a few questions/concerns about summer patch and related root rot/patch diseases on heat stressed Poa and bentgrass.
There are many plants which are still showing the strain of the difficult summer, and some patchy or circular symptoms of weak turf may still be seen.
In some cases, there may be an actual parasitic attack on the roots of weakened plants by root rot fungi and relatives (minor pathogens), but in other cases the patches may simply be due to weak clones or groups of plants that are slower to recover from the summer stress.
(For example, we have seen clones of Penncross or south German bents that are weaker than others and are more sensitive to weather extremes.)
Also, some of the suspected patch symptoms may actually be leftover fairy ring damage, or "subliminal" brown patch.
Some areas thinned by Rhizoctonias may now be colonized by algae, which can give the patch a strange appearance and could be confused with other diseases.
There have still been only a few reports of Gray Leaf Spot on perennial ryegrass in the mid-Atlantic states through Kentucky (none that we know of in IL).
However, the weather pattern we seem to be entering now (warm and humid with more thunderstorms) should be conducive to moving the spores around and favoring infections.
Readers in central IL with ryegrass in tees, fairways, and roughs should be watchful for the sudden wilting and collapse of turf that could indicate a developing gray leaf spot problem.
We are also coming out of a cycle where dollar spot activity has been fairly minimal (? for some anyway). First it was too hot in late July and early August, then it was too cool.
With the warmer temperatures and humidity of the last couple of days, it is likely that dollar spot activity will pick up again heading into its normal late summer peak.
Also, many of your treatments over the last few weeks to try to stave off Pythium and brown patch will not have had much effect on dollar spot (unless you threw some chlorothalonil or iprodione in the tank!), so there may not be much residual control in the offing.
On a final note, you may see anthracnose acervuli (microscopic fruiting bodies with dark spines sticking out) on the older, senescent leaves of injured Poa and bentgrass.
For the most part, this infection is opportunistic and is a RESULT of, and not the CAUSE of, the heat stress damage of the last few weeks.
However, if infected plants also have stem, crown or stolon infections (e.g. basal stem rot), the disease can be much more harmful and should be treated with a systemic fungicide if possible (a DMI or strobilurin).
So keep an eye out for this as well.
Have any interesting experiences during the last few weeks???!!?!?
Please pass along any observations or insights to Kane or Wilkinson.
Hang in there, we are officially over the hump!
YOUR FEEDBACK OF OBSERVED PEST PROBLEMS IS IMPORTANT
Please respond with your observations to pestalert@interactiveturf.com so we can build our pest activity data base and report those pest outbreaks back to our readers.
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