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Welcome to week 6 of the IPM Update.
We are now in the "middle" of the summer season and, so far, it is turning out to be a very pleasant experience for our golf course turfs - especially compared to last year!! (Thirty-one days to August 15th!) Thanks to those of you who have responded with information and questions, you are helping to provide a more useful and interesting update.
Weather Update
Although there has been some hot and humid weather finding its way into central and southern Illinois, northern IL and the Chicago metro area has avoided any prolonged heat and humidity.
Forecasts for the next several days indicate that this pattern will hold, as daily high temps are predicted to stay in the low to mid 80s.
The official weather station for Chicago (O'Hare) has yet to record a temperature above 90 degrees for the year 2000 (I like it!).
There is some hot weather building over the northern plains, but it is hard to say if/when the moderate weather patterns in northern Illinois will change.
Diseases
We are starting to see a shift toward other more common summer diseases, but Dollar Spot remains the big story of 2000.
Dollar spot is favored by moderate temperatures (low to mid 80s F), high humidity (and frequent rainfall) and low soil and plant fertility (especially low N levels).
Dollar spot continues to hit fairways particularly hard, especially patches of Poa trivialis (some of those patches now look like they have been sprayed with Roundup).
Many superintendents are reporting less than 2 weeks control out of normally long residual systemic fungicides.
Frequent rains and good growing conditions are probably contributing to lowered N fertility levels in fairways and on sand greens and tees.
I strongly recommend you consider applying a soluble N source (eg urea) tank mixed with your next dollar spot fungicide.
Summer patch and anthracnose are starting to show on Poa annua, and I have seen summer patch symptoms on lawn height Kentucky bluegrass as well.
Summer patch symptoms can be very distinctive on mixed Poa annua/bentgrass greens.
You will often see a thin, yellow, circular ring of declining Poa - with a solid patch of healthy bentgrass filling in behind the advancing disease.
Just as take-all patch fungi won't infect/kill Poa species (and Poa species will fill in the center of a chronic take-all infection), summer patch fungi won't infect/kill bentgrass.
Many superintendents who have had problems in the past with anthracnose on Poa greens are reporting excellent results with Heritage fungicide.
If you have commonly included a benzimidazole derivative fungicide (eg Cleary's 3336) in programs for anthracnose control, you should consider switching to a DMI or Heritage/Compass fungicides to avoid developing a resistance problem.
A new disease is appearing on the horizon for creeping bentgrass greens - "Bentgrass Dead Spot".
(what a name?.)
BDS is caused by a fungus called Ophiosphaerella agrostis, which is in the same group of patch disease causing ascomycete fungi as Gaeumannomyces (take-all) and Magnaporthe (summer patch).
BDS is becoming referred to in common parlance as "the ballmark disease".
Symptoms often start as small sunken, reddish brown or orange/rust spots about the size of a ballmark.
These "mini-patches" can get a little larger and develop a green center if left untreated (or miss-identified/miss-treated).
Symptoms can be easily confused with dollar spot, summer leaf spots, anthracnose, and ballmark damage!!!
Since this disease is very new, it is hard to say what conditions are most likely to lead to its occurrence.
So far, I have seen it (confirmed) twice in Chicagoland, both times on newly seeded, resurfaced greens that had been "sterilized" before seeding with methyl bromide.
The disease has been found more frequently on the east coast, and seems to occur mostly on newly constructed or renovated greens.
I have seen it on L93, Providence and SR1119, but wouldn't be surprised to find it on other varieties.
NOTE : There are now many years of research data out of the U of IL (Hank Wilkinson's program) that show increasing amounts of dollar spot control with increased fertility and soluble N in tank mixes.
Also, we have data to show that annual N rates on fairways should be in the 3 LB per 1000 range to help suppress dollar spot.
If you are having chronic dollar spot control problems, I suggest you re-examine your fertility programs!
Insects
Japanese beetle populations are exploding in certain areas, and little leaf lindens are under attack! I have also heard of some Ataenius larvae causing damage on fairways in the Chicago area - breaking through an earlier March II application.
If you have some 'localized dry spots' showing up in this warm and wet weather, better check for grubs! The big news on the bug front for the next few years may be the invasion of Illinois by Gypsy moths.
I was in grad school at Cornell when the first big outbreak occurred in New England and upstate New York; the damage was quite dramatic when gypsy moth populations exploded.
Gypsy moths have been confirmed in several counties in northern Illinois, and the state is considering a quarantine for plant material coming out of Lake and several other counties.
There is a good summary article in the Friday Chicago Tribune and more info available on the web.
Check out the gypsy moth digest at:
http://fhpr8.srs.fed.us/wy/gmdigest/gmdigest.html or do a search for Gypsy Moth Info.
Weeds
With the amount of rainfall we have had in northern IL for the past 6-8 weeks, algae has become a chronic problem on greens.
Wet areas often thin out - and algae then invades.
Once the turf dries out a little, algae encroachment can remain or become worse, especially if the thinned areas are on the edges of greens where mower or foot traffic further weakens the turf.
Some physical/mechanical changes can help improve an algae problem, such as quadratine aerification, topdressing, reduced mowing or raising the height of cut.
It looks like a good year for crabgrass? white clover, chickweed, plantain?
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