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Update (4/24/2013)

Large Patch Warning

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Missouri weather in April has been the extremes of cold and wet.

March and April spring temperatures have averaged 3-6 degrees F below normal, ringing in the coldest early spring period since 1996.  Frost, and even a stray snow shower hit areas north of I-70, knocking back warm season turfgrass growth and the ill-timed tomato planting.  Pat Guinan, state climatologist called this period a “reality check” after last year’s blazing Missouri spring, and that we’ve gone from one set of extremes to another.    

Keeping within that theme, precipitation has been above normal for every month in this young 2013, with more than 15” accumulation in many areas of the state.  This abundance of moisture has fortunately busted the drought (for now), and unfortunately along with northern snowmelt has caused rivers to swell to levels not seen since the historic floods of 1973.  Is the drought over?  Maybe.  Remember, however, that April 2012 had 7-8” of precipitation before the spigot got shut off during last year’s historic drought.  Extremes…

The forecast is promising as temperatures look to rise to near normal levels for the state, and some drying starts to occur this weekend and into next week.  There are even whispers of 80F highs for middle of next week in mid MO, which would set spring into full motion.  If you’re wondering the latest recorded spring frost in mid Missouri was May 9th 1906.   

Quick Hits

Soil temperature 5 d averages are 46 - 58 F across the state.
  • Along with air temperatures, soil temperatures have plummeted over the last 10 days (see above).  If you have already applied fairy ring prevention on golf greens with a DMI fungicide, you should still be okay with the 2nd application 28 days later.  The window, however, should still be open for next week if you haven’t applied yet.  Since we are so late this season, consider making the 2nd application 21 days later instead of 28, so potential high temperatures will be less of an issue.  Click here to see the previous report detailing the DMI preventive strategy.    
  • There should also be a longer window for those along I-70 that still have yet to put down a crabgrass pre-emerge.  We have not seen crabgrass germination yet in Columbia, but I’m certain it has emerged in the Bootheel, and probably also beginning to germinate in Springfield/Branson.  In CoMo, we do have quite a bit of knotweed (the 1st summer annual to arrive) scattered along the margins of campus sidewalks, which also a good indicator of compaction.  The concrete is quite hard on the feet of students…
Waitea patch on Poa annua on greens observed in Missouri this past week.

  • Waitea patch (aka brown ring patch) was sampled from a golf green in mid Missouri last week.  This goes along with an unconfirmed report of the disease in Kansas City the week before.  The disease occurs solely on Poa annua, causing a bright yellow chlorosis in arcs or rings before a dieback of leaf tissue.  Although it has been reported in Japan to infect creeping bentgrass, there have been no observations of the disease on creeping bentgrass in the U.S.  In California and northern U.S. regions where Poa greens are managed, this disease has become quite the issue and fungicide treatment is often necessary.  Several observations have come across social media indicating the disease is active in the Northeast. In our area, however, the disease doesn’t usually become severe enough to require treatment and adjoining creeping bentgrass normally just takes over.  Leaving some regional superintendents asking “Where can I get some of this stuff?”
  • Turfgrass pathology?  Turfgrass pests in general?  There’s an app for that.   Dr. John Kaminski from Penn State University, the social media mogul of the turfgrass science world, has developed an application designed to network turf managers, and allow for sharing of scouting reports and other pest management information among users and turf scientists.  It was just released in the iTunes store today, so I haven’t gotten a chance to use it much yet.  It seems like a fantastic idea, however, and scouting is a heck of a lot easier on a regional scale with many more eyes than just your own.  It is available for Google Play and iOS; click here to download for Google Play (Android) or click here to download for iOS.      

Large Patch: Anytime Now...

Initiation of a large patch trial in Illinois to investigate the impacts of nitrogen source and fungicides applied in the spring.

I have not written a report feature on the same disease two times in a row, but for those managing zoysia, this disease needs to be at the forefront.  I anticipate next week’s warmup to generate a litany of reports of large activity, as the environmental conditions have been ripe for severe outbreaks.  These conditions include waterlogged soils, and a zoysia plant that has been subjected to a see-saw of slightly warm to freezing temperatures that have caused slow growth and a gradual delay in emergence from dormancy.  Several other regions just to our south have been tweeting severe large patch reports, and we may be next in line very soon.     

Since the weather finally let us, Daniel Earlywine and I meandered across the raging Mississippi this week into Illinois to initiate a study investigating spring cultural and chemical practices for large patch control (see above).  In particular, we are researching the use of different fungicides and nitrogen sources alone or in combinations to prevent large patch occurrence and improve spring turf quality in in areas with residual fall symptoms.  Conventional wisdom states that nitrogen applications exacerbate symptoms as they do with brown patch outbreaks in tall fescue.  This has not been explored fully though in regards to the use of different nitrogen sources, particularly ammonium-based vs. nitrate-based. 

This, along with an on-site trial in Columbia, are the first field experiments we’ve initiated as part of a funded grant from the 2013 USGA Turfgrass & Environmental Research Program.  With Dr. Megan Kennelly at Kansas State University as a collaborator, we hope to shed some light on the dos and don’ts of spring fertilization of zoysia with field and laboratory experiments.  The third trial investigating nitrogen source alone hopefully will go out next week as soil temperatures may actually hit our target threshold of 60 F.              

Have a good week. 

Lee Miller
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Extension Turfgrass Pathologist
University of Missouri