ZOYSIA MANAGEMENT: How many fungicide applications will you make for large patch control and when will you apply them?

2-Fall and 1-Spring
1-Fall and 1-Spring
1-Spring Curative

Update (09/18/2015)

Summer Feeling Starting to Fall

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Lobenstein Scholarship Tournament

The Lobenstein Scholarship Tournament is scheduled for Friday, October 2nd, 8 am at Columbia Country Club.  This is the day before the SEC Opener for the Mizzou Tigers vs. the South Carolina Gamecocks, so come out and make a full weekend out of it. 

The tournament will benefit the Lobenstein Fund, which has the sole purpose of annually warding two deserving MU undergraduates (one in Turfgrass Science and one in Horticulture Science & Design) $1000 scholarships.  The event will be a 4-man scramble, and the field is limited to 72 players.  Hole, prize and beverage sponsorships are also available.

More information is provided on the flyer below.  To register, go to  Hope to see you there!


Despite a brief foray into fall last weekend, September has been very warm and dry.  Across the state, temperatures are 3 – 4 degrees above normal for the month, sparked mainly by a very summer-like start. As detailed below, these warm temperatures sparked a few unexpected summer problems in early September.  Precipitation across the region has been sporadic. The west and southwest portion of the state have received above average rainfall due to a heavy rainfall event on September 7 and 8, while the rest of the state is below normal.  Due to the lack of precipitation, some soils in the central portion of the state are cracking at the surface, and non-irrigated cool-season turfgrasses, tired and short-rooted after a long summer, are going into drought dormancy.  Seeding and establishment efforts have been difficult, as supplemental irrigation has been required frequently over the last week to facilitate germination.  

A cold front is slowly sliding to the west and hopefully will provide the central and eastern portion of the state some rain to remediate mild localized drought.  Although we are set to cool off in the short-term (providing nice weekend football weather), the rest of September is forecasted for much of the same warm and dry weather pattern.  As noted in the previous update, day length is thankfully getting shorter, with fall equinox (~ 12 hour daylength) occurring next week on September 23.  Also, above-normal temperatures in September are the mid 80’s as opposed to the mid 90’s in June – August, so temperature at least shouldn’t put a huge damper on cool season turfgrass recovery. If the temperatures continue to be warm, however, it will be interesting if we approach some of the old records for hottest Septembers in Missouri.   


Quick Hits

  • In the first week of September, brown patch was observed on a softball field apron in mid Missouri.  This occurrence was odd, not because it was in September, but because it was on a spring sodded ‘HGT’ Kentucky bluegrass.  Kentucky bluegrass is less susceptible than tall fescue to brown patch, but conditions were particularly conducive this season ,and we noticed the disease prevalently on both species.  A quick application of Heritage (azoxystrobin) was applied, which, along with cooler temperatures, facilitated recovery.  Although this wasn’t the case here, the outbreak does bare a warning in attempting to “jump the gun” on fall nitrogen fertilization by beginning in late August or early September.  If hot weather does occur during this period, a nitrogen application will spark brown patch and compromise a very susceptible, still summer-stressed, plant.    
  • Don’t forget about basal rot anthracnose.  A bentgrass putting green sample was submitted earlier this week from south St. Louis that was loaded with the disease. Anthracnose is easily neglected this time of year, but conditions are often ripe for it.  Bentgrass gets hungry for nitrogen in the fall, as temperatures dive into the perfect range for growth and recuperation from summer stresses.  To coincide with this need, anthracnose is a low N disease, occurring and causing considerably more damage when the plant is under-fertilized.  Superintendents may also press the issue of raising greens speeds a bit more in the fall as temperatures subside.  Going back to grooved rollers and lowering mowing heights before important fall tournaments may also set the stage for this disease.  If you managing bentgrass varieties susceptible to anthracnose infection (i.e. ‘Penncross’, ‘Pennlinks’, ‘Providence’, ‘Seaside II’, ’Brighton’), be on the lookout for this disease now.  As mentioned, a little extra nitrogen will help reduce anthracnose severity.  At this time of year, a tank-mix combination DMI plus chlorothalonil application should be a good curative treatment.  Do not rely on iprodione or thiophanate-methyl alone for anthracnose control.  

  • In early September, a superintendent in mid-Missouri reported decline on low areas of his greens, along collars and green margins. Upon inspection, large black layers (2-3” thick) were noted about an inch below the turf surface.  In this case, water was trapped along the interface of the sand-based rootzone and the native soil surrounding the green.  In May, June, and early July of 2015, many in Missouri didn’t have to turn on irrigation systems very often as soil were frequently saturated by rainfall events.  Soilborne issues can steadily accumulate over the summer and culminate in early fall with turf loss, unfortunately at the very time we are ready to exhale.  Looking back to last year’s report, these problems mirror exactly what was reported in early – mid September 2014.  Aerification is recommended in this situation to reestablish airflow into the rootzone and allow for a dry-down.

  • Also reminiscent of last year, we had a putting green sample submitted this week from St. Louis with a considerable infestation of summer patch.  Typical symptoms include a gradual thinning or decline, most often mottled, but sometimes in a ring or frogeye pattern.  This is another case where the disease steadily increased throughout the season, and accumulated enough root decline equity to cause symptoms.  Since the disease is difficult to control curatively, a strong combination fungicide such as Lexicon (pyraclostrobin + fluxapyroxad) or Briskway (azoxystrobin + difenoconazole) may be the best recourse for recovery.  A small addition of ammonium sulfate (~ 0.2 lb N/1000 sq ft) can also aid in disease suppression and encourage recovery.  Remember the disease is soilborne so the fungicide and nitrogen should be watered-in immediately with 1/8” of irrigation. 

Falling Towards Disease Control on Warm Season Turfgrasses

Large Patch on Zoysia:  Questions are beginning to flow in about application timing for large patch control in zoysiagrass.  My political response is it depends… on how many applications one plans to make.  If three applications are planned, the first should be made in the fall when 2” soil temperatures ~ 70°F (currently range from 75-78°F across the state) with the second made 21 – 28 days later.  The third should be applied in the spring, sometime in April, in the period just prior to or just after zoysia green-up.  If two applications are planned, rather than the common two fall fungicide applications, my current recommendation is one fall application made later in the season (early to mid October or when 2” soil temperatures are ~ 60 - 65°F) and one made in the spring.  In extremely wet springs like this past one, some breakthrough occurred on zoysia stands that only received fall applications.   

If only one application is feasible, the best timing for this application is in the spring rather than fall.  Our research demonstrates more consistent efficacy from spring than fall applications during the spring symptom period.  Spring symptoms are more important and conspicuous in Missouri than in the fall when the zoysiagrass will be soon entering winter dormancy anyway.  For more information, click here for this previous update.

Spring Dead Spot on Bermudagrass:  In the next week or so, spring dead spot control should also be on the minds of athletic field managers in the state.  Spring dead spot, a soilborne disease, is more difficult to control, and when it sets in oftentimes requires a multi-year integrated strategy.  In our most recent fungicide trials, Velista (penthiopyrad) applied at 0.5 - 0.7 oz/1000 sq ft twice in the fall (mid-September and mid-October) has provided very good control after a single year of application.  Although not on the regular label, Velista has a section 2(ee) label for spring dead spot control.   


Lee Miller
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Extension Turfgrass Pathologist
University of Missouri