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Weather Update
Since the last update, we have moved through another weather cycle - from cool to hot, and back to cool.
June 25-30 was a little hotter than normal, with daytime highs running in the upper 80s to low 90s.
It was a fairly dry heat most of the week, with the humidity not picking up until Thursday or Friday.
Also, the overnight temperatures stayed fairly cool, with temperatures dropping into the low 60s.
There were a few reports of fungal diseases active, but seemingly not severe.
Dollar spot should be the most active disease at these temperatures.
A strong cool front is crossing the area today, and the radio reports possible overnight lows tonight in the 40s (!! - northern Wisconsin weather), and daytime highs this week in the 60s and 70s.
If there were any hot temperature diseases or heat stress affecting plants by the end of last week, these cold overnight temperatures will put a stop to that.
Unfortunately, with the cool weather and low humidity, we have now entered a semi-drought period.
There has been no significant rainfall since the last report (June 21), and we have ended the month with a precipitation deficit of about 30-40 percent.
Much of the June rainfall came in the first week of the month.
Many un-irrigated turf areas are looking wilted, or are entering dormancy (take my yard for example).
Mounds in fairways, and humps on greens have needed hand watering, as have many collars.
(Why do collars dry out or go under heat stress so easily/often??? Beats me.)
Localized dry spot problems will be showing up, as should some types of fairy rings.
Diseases
Low relative humidity (dew point) and lack of rain is keeping a lid on many summer foliar diseases; dollar spot will continue to come and go as temperatures cycle in and out of the favorable range.
Red thread disease has been found active in some bluegrass and ryegrass turfs at rough height.
The symptoms of red thread are very similar to dollar spot on longer grasses, but diagnosis is fairly routine if you can find the light red or pink colored hyphal strands of the fungus bridging from leaf to leaf.
Like dollar spot, red thread is favored by low fertility and droughty soils.
The heat and drought stress of last week also brought on more symptoms of root rots, primarily take-all on bentgrass and summer patch on Poa annua and Kentucky bluegrass.
Take-all symptoms should be on the wane in the next week or two; usually take-all appears in late May or early June and fades away in the heat of summer (as long as the disease isn’t severe enough to kill infected plants!).
Summer patch starts showing symptoms in July and can last well into September on Kentucky bluegrasses.
Remember that if you get patch disease symptoms at this time of year (June-August), fungicide treatments lack effectiveness since the root rot damage has already occurred.
Areas that are chronically (yearly) affected by root rots should be treated preventively with systemic fungicides such as a DMI or strobilurin.
Insects
First emergence of adult Japanese beetles is starting to happen in central Illinois and in some areas of northern Illinois and southern Wisconsin.
Emergence of adults from the pupal stage was delayed by the cooler than normal weather in early June.
Watch for early feeding on their favorite tree and shrub hosts, especially lindens, crabapples, willows, birch, and roses.
Generally, JB will start feeding on the uppermost leaves, which can sometimes be hard to see from the ground.
If you plan to treat a tree or shrub for JB, early treatments are best since feeding injury attracts more adult beetles.
See this week's Home Yard and Garden newsletter for more info on JBs, plus some news on tent caterpillars, bag worms and other nasty bugs.
Weeds
The moss saga continues, and we still know of no treatment that is working at a high level without some danger of phytotoxicity on the turf (especially in the heat).
Some turf damage has been observed with the new product Terracyte where small areas of moss were treated by hand with the granular formulation.
Treatments with other mixtures containing wetting agents, dish detergents, or ferrous sulfate will also cause some tip burn if applied at high temperatures.
Treatments for moss with copper products should be limited to spring and fall also.
I continue to see clover and chickweed on some tees and fairways around the area.
Remember that some herbicides with phenoxy chemistry can burn creeping bentgrass (especially in the heat)...
Crabgrass has emerged and is becoming easily visible in most turf situations.
There are a few crabgrass herbicides that can be used effectively in early post-emergence situations (eg Dimension, Acclaim, Drive), with quinclorac (Drive) having good safety on bentgrass and the best efficacy on larger (older) crabgrass plants.
Be sure to read and follow label instructions for rates and application techniques, and don’t treat drought or heat stressed turf…
Please respond with your observations to newsletter@interactiveturf.com.
Enjoy the cool week and take some time to come down to the Western Open at Cog Hill.
While you are there, come by Midwest Golf House and say hello!
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