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Weather Review:
Our first encounter with an extreme summer weather pattern lasted
a few days longer than initially predicted, but we are catching
a cool break for the next couple of days. Another “hot dome” of
high pressure may arrive next week, as there are still high temperatures
in the western states and central plains.
From June 20 to July 9, the Chicago area had 11 days with a high
temperature over 90 F and 16 days over 85 F. Fortunately, some
of those days had fairly low relative humidity. For central Illinois,
that same 20-day stretch beginning June 20 had 14-15 days over
90F, and every day was at least 85F for the high. And from June
30 to July 8, every day saw at least 90 F on the thermometer (no
wonder crabgrass is such a problem!).
Following a very wet spring, central Illinois has been in a near
drought condition, with little measurable precipitation since
early to mid June in most locations. The Chicago area has had
a little more precipitation, but this has been scattered and spotty.
In all, the heat and humidity levels are similar to last year.
Let’s hope most of the extreme heat index days are past by early
August -- last year most of the heat was gone by August 10.
Diseases:
This prolonged hot and humid spell brought out the usual high
temperature summer diseases, primarily Pythium blight.
Numerous
reports of Pythium outbreaks on tees and fairways have
been received since June 26, with more intensive activity
reported following scattered afternoon or evening thundershowers,
especially in low areas and where air movement is restricted.
Less Rhizoctonia Brown Patch (R. solani) has been
reported, and for the most part the symptoms have been fairly
mild (‘subliminal’). Dollar spot activity usually slows down when
temperatures stay consistently in the 90s, and this has been the
case this year – although there are certain biotypes of the pathogen
(Rutstroemia???) and certain sites where the disease may
remain active at higher temperatures.
Other diseases that have been observed and reported through InteractiveTurf.com
in lower frequency include basal
stem rot anthracnose on Poa annua, red thread on most
species in low fertility areas (eg primary roughs, bunker banks),
and fairy rings. Fairy rings can occur in practically any turf
setting, but have been especially troublesome over the last few
years on greens and on some fairways. Fairy ring activity usually
picks up with warmer drier weather, and can cause severe damage
to turf when extreme heat or water stress affects the turf in
the ring. It appears that some of the fairy ring fungi also contribute
to development of localized dry spots, which can cause further
turf decline and require intensive treatments (e.g. core cultivation)
to correct the problem.
Several diseases that were active in early to mid June have now
subsided with the onset of hot weather, especially the Rhizoctonia
zeae
yellow ring on Poa and take-all
patch on creeping bentgrass. Take-all patch symptoms can persist
in some cases through the summer, but can often be alleviated
or ‘masked’ by increased irrigation (hand watering) to avoid water
stress and additional N or Fe fertility to improve the color and
recovery of infected turf.
Insects:
Adult
Japanese beetles were observed in increasing numbers by the
end of June in central Illinois, and are now emerging rapidly
in the northern part of the state. We may have a bumper crop of
JB adults this summer, because of the mild winter and the probability
that more grubs survived through to the pupal stage this spring.
In fact, this could be a big year for all scarabeid beetles (grubs
and adults) this year, and we recommend that scouting for possible
Ataenius grub damage should commence now (make sure those localized
dry spots really are dry underneath!).
Cutworms
have continued to feed through the hot spell, and mound building
ants also have caused problems around the area, especially on
sand based rootzones of greens and tees. For some superintendents,
ant mound damage has become the number one insect problem on their
course. Unfortunately, we still haven’t found a treatment that
will give more than a couple of weeks of control (suppression).
There are a couple of new bait products coming to the market that
may work better, but the jury is still out for now. We have written
about Maxforce bait in the past, which has had some success. A
new bait product based on the Aventis/Bayer insecticide fipronil
is becoming available (it has a fire ant label now), which may
also work to reduce mound-building ant colonies.
Weeds:
Summer annual weeds are in full “bloom” by now, especially the
warm season annual grasses like crabgrass and goosegrass. For
a summary of control measures, see the ITF turf tips "Postemergence
Control of Warm Season Annual
Grassy Weeds" and "Stemmy
Turf and Postemergence Annual Grassy Weed Control" by
Luke Cella, Tom Voigt et al., which is posted to the IT website
and can also be found on the IL
Turf Foundation website.
High temperatures and humidity can often cause fine turf to thin
out, which usually means moss, algae, and other invaders can move
in. We still have no magic bullets for moss or algae control,
but the best preventive medicine is
to grow dense, healthy turf. Repeated treatments (at light rates)
of soap-based products (like Ultra Dawn) have been shown to gradually
reduce moss patches, and spot applications of Terracyte have worked
well at some locations. Mancozeb products (like Fore) and chlorothalonil
(Daconil Ultrex and Daconil Zn) have been effective in reducing
algae infestations when used in a continuing program. Remember
to be careful with any kind of herbicide or moss/algae control
program under extreme heat and high humidity conditions to avoid
phytotoxicity.
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The University of Illinois Turfgrass Field Day is scheduled for
August 1st, and as part of the program a special
instructional seminar on the use and application of the InteractiveTurf
program will be held in the computer laboratory of the Agricultural
library on campus. This seminar/open discussion will be a great
opportunity to voice your opinion on the program and to steer
its development in a way that will most benefit your management
program. If possible, please make plans to attend.
Please keep us informed as to the health and condition of your
turfgrass in these hot, trying times. Drop us an email, fax
a pest alert, or give us a phone call to let us know what
is going on in your neck of the woods.
Randy Kane
CDGA
Director of Turfgrass Programs
Midwest Golf House
11855 Archer Ave
Lemont, IL 60439
630-257-8126
Lee Miller
CDGA
Manager of Turfgrass Research
Midwest Golf House
11855 Archer Ave
Lemont, IL 60439
630-257-2005 x.111
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