SURVEY QUESTION

LAWN: What percentage of lawns do you seed in the fall?

None
less than 25%
25-50%
50-75%
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Update (08/23/2016)

Summer’s Sting Subsides

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Weather

Welcome Run of Fall-Like Temperatures

  1. Mid-August finally yielded a breath of cool air to tired cool-season grasses. - Source: Pat Guinan
  2. Heavy rains (+12 inches in some areas) hit the eastern part of the state. - Source: NOAA

The cool breezes and low humidity of mid-August have been a welcome relief for golf course superintendents in the region.  Over the last 7 days, mean high temperatures were 2 to 6 degrees below normal in Missouri, giving weary cool season turfgrasses a much needed break.  June, July, and early August took their toll with above normal temperatures and in July with very high humidity (4th highest average dew point on record).  As stated in some previous years, it wasn’t the high highs that got us, but the high lows.  Over the last 90 days, low temperatures have been 3-4 degrees above normal, meaning sustained high soil temperatures (~90 F in some areas) and no rest for weary cool season grasses at night.  Tall fescue/Kentucky bluegrass lawns that were mowed too low or overirrigated (little supplement necessary in July) were particularly hard hit with disease, as were bentgrass putting greens with both disease and pure physiological decline.  Hopefully this fall recovery-type weather is here to stay. 

An intense tropical system brought considerable rain to the Bootheel (over 12 inches in some areas) and St. Louis last week, while Kansas City and the western portion of the state have been on the dry side this month.  Slightly above average chances of rainfall are predicted over the next 6-10 days, with an above average chance of higher than normal temperatures.  The good news is the average temperature for this time of year is starting to plummet towards the mid 80s, and the daylength or overall time period of intense height is smaller.  Thirteen hours of sunlight delivers a much lighter punch than the near 15 hour days in June and July.     

Late August Outlook

  1. Above average temps expected to close out August in MO. - Source: NOAA CPS
  2. Above average rainfall pattern expected to stay in the late August. - Source: NOAA CPS


Quick Hits

  • Dollar spot weather should be upon us now, as we shift from a severe summer of Pythium, brown patch, and other summer diseases.  For those with Kentucky bluegrass lawns or sports fields, a directed fungicide application is normally not necessary.  Instead, realize that dollar spot is more apt to infect an under-fertilized plant and a nitrogen fertilizer application will help control the disease.  Also remember that fall is the best time anyway to apply nitrogen to cool-season turfgrasses since the threat of Pythium and brown patch is in the rear view mirror.

Scout for Fall Armyworms

  1. Start scouting for presence of fall armyworms. Young worms are green, turning brown at maturity.
  2. Distinct Y-shaped marking on the head, and net-like markings around the eyes.

  • Fall Armyworm Warning:  Fall armyworms have been noted in agricultural fields in southern Missouri, so it’s time to start scouting for these pests in tall fescue.  Damage from this pest is erratic so preventive applications are not necessary.  Last year we did not hear of any instances of turfgrass damage, but 2014 was a doozy.  To read more about the 2014 outbreak, click here.  Annual white grub damage should also be starting soon, made most obvious by skunks, armadillos or raccoons damaging the turf as predators. 
              
  • Prepare for Seeding: No matter if it’s a renovation, reseeding of bare areas, or overseeding to increase tall fescue/ Kentucky bluegrass density, now is the time to purchase seed and begin planning.  In areas with weedy bermudagrass, Pylex herbicide applications can be used to beat back the bermuda and allow for a better chance of establishment.  Other herbicides for broadleaf control should be used with caution, however, paying attention to the label for appropriate application intervals prior to and after reseeding.

2015 NTEP Bentgrass Rating
Number in parenthesis indicates percentage of total sites nationally that had the entry in the top quarter of all cultivars.


  • As for what variety of turfgrass species to purchase, be sure to do your homework and check www.ntep.org for the latest updates.  For tall fescue, varieties bearing the LS (lateral spread) or SRP (self-repair potential) designation seem to be scoring well, and pay particular attention to the brown patch ratings which can be viewed here.  Most tall fescue seed is in a blend, so shoot for at least one of your targets from the NTEP data.  If seeding bentgrass is on your agenda, see a graph of the 2015 data above for the newest and experimental cultivars from MO.  Note that disease management was kept to a minimum, as after all a pathologist was involved…

Summer 2016 Nematode Update
– Bentgrass Putting Greens*

Sting Nematodes Found Again in Kansas City Area

  1. Stings are relatively large nematodes (3 mm in length), making them very impactful on root health.
  2. The large stylet (or fang) of a sting nematode which allows it to pierce deep into root tips and stunt growth.


Awful tired now boss. Dog-tired.”  This phrase in the movie “The Green Mile”, as painfully uttered by the hero John Coffey (played by actor Michael Clarke Duncan), sums up perfectly the current health of a creeping bentgrass putting green.  As stated in the previous update, physiological decline, or the soggy hot root syndrome, has been commonplace in the region after the brutally hot and wet conditions of this summer.  The June heat was the set, and the sustained heat and persistent rainfall of July was the spike on bentgrass roots. 

Several of the submitted bentgrass samples to our diagnostic lab are also forwarded on to the MU nematology lab for a check on nematode populations that could stunt root growth.  We observed root knot nematodes that again were at levels on some courses in St. Louis and Columbia that could impact turfgrass health.  Lance nematodes were also noted earlier in the season at a course in southwest MO with above threshold levels. Ring nematodes were at or near threshold levels in a few other instances as well.  Although bentgrass roots didn’t need any help in declining this summer, in very few cases have we seen devastating levels of these nematodes where they were deemed the primary or sole factor in bentgrass decline.  At least until last week. 

Sting nematodes were found at significant levels (24 – 192 stings per 100 cc soil) on several putting greens in the Kansas City area.  Relatively speaking in a very microscopic world, sting nematodes are big nematodes with adults up to 3 mm long.  The sting nematode also carries a big gun, in the form of a long stylet, or hollow fang, that pierces near root tips for feeding.  The large stylet causes extensive tissue damage which provides a perfect infection court for other pathogens like Pythium spp. or the ETRI pathogens (ectotrophic root infecting fungi) that cause take-all or summer patch.  Because of their size and destructiveness, stings carry the lowest population thresholds among the turfgrass pathogenic nematodes.  On bermudagrass and zoysiagrass golf turf in Florida, the moderate risk threshold is 10 and the high risk threshold is 25 stings per 100 cc soil (Crow, 2015).  Those thresholds would be set for warm-season turfgrasses grown in a tropical climate.  In corn and soybeans, a common threshold is set from 1-10 per 100 cc soil.  In this region, stings are impacting a cool-season species growing well out if its comfort zone in both mowing height and our oftentimes brutal transition zone summer.

The logical question is “where did they come from?”  Since stings are such large nematodes, they should need a sandy soil with large pore spaces to move and thrive.  Golf course putting greens with 85 percent + sand rootzone are a great habitat, but how did they get there?  We have intermittently observed cases of damaging sting nematode populations in the Kansas City area since 2010, but have not detected them at all in St. Louis, Columbia, Springfield or other parts of Missouri. Because of this, it’s doubtful they are present in the topdressing or greens grade sand harvested from the Missouri River Bottoms that is commonly used in the region.  In one earlier case, the introduction could have been zoysia sod harvested in sandy soils in lower Arkansas or Oklahoma and brought in, but that mode of introduction has not been consistent.  Upon inspection of several soil surveys in the Kansas City area, the predominant underlying soil type seems to be a Kennebec series silt loam.  The sand content of the upper horizon is stated at less than 10 percent, with a friable moderate fine granular structure.  Although this doesn’t seem to be a suitable habitat for sting nematodes, more research is necessary to determine that they can’t survive in this soil type.   

Luckily, there will be new tools available for superintendents dealing with sting nematodes in Kansas City.  Indemnify by Bayer has received a federal registration, and will hopefully be broadly available in the area.  Similarly, other companies are working on products that can hopefully tame the extra spike, or stylet of the sting nematode.

* To my knowledge, lawns and other higher cut turfgrasses do not have issues with sustaining considerable plant parasitic nematode populations, and sting has not been found associated with decline of higher cut turfgrasses in this region.   

Lee

Lee Miller
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Extension Turfgrass Pathologist
University of Missouri