SURVEY QUESTION

ALL: Are you done with management practices on turfgrass this year?

Yes
No - Fertilization needed
No - Still mowing (tall fescue or KBG)
No - Will seed
No - Will topdress zoysia
No - Another fungicide application needed

Update (11/8/2019)

Late Hits

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illustration of the state of Missouri. Missouri Green Industry Conference logo

Register Now:
Missouri Green Industry Conference - Dec. 4th

It's not here quite yet, but the weather sure feels like winter conference season. The first event on the Missouri docket is MoGIC, which will be held in the St. Charles Convention Center on December 4. Just a few of the highlights include:

  • Sports Fields Track - Jeff Salmond from Arkansas football and Dr. Brad Jakubowski from Penn State
  • Golf Track - Dr. Billy Crow from UF delivering the low down on nematodes and Isaac Breuer/Scott Woodbury talking pollinators
  • Lawn/Landscape Track - Kelly Dowell talking recruiting, Dr. Camilo talking native bees and Glenn Kraemer and I discussing pest management for lawns.
  • Keynote by Josh McPherson, Mizzou Director of Turf and Grounds, discussing self-care tactics for the Green Industry

On top of these, three other tracks are offered along with a pesticide recertification track. Go to http://mogic.org for all of the details and to register.


Weather

Fast Fall Towards Winter

  1. Steep drop into winter-like temps in October. – Missouri Climate Center
  2. Dark, dark blue indicates low temps will continue into mid November. – NOAA

As warm as September 2019 was, the bottom certainly dropped out quickly in October. The statewide average was 53.7 F or 3.3 degrees below average. This made October 2019 the coldest since 2009 (which was the 4th coldest on record). The first freeze event occurred for much of the state on October 12, when temperatures dipped into the upper 20's/low 30's for much of the reason. This is a few days earlier than average for northern Missouri and 7-10 days earlier for much mid Missouri and the Ozarks (see the MO Frost/Freeze Guide to dive head first into the numbers). The second temperature dive occurred on Halloween, when a rare October snow event (for much of Missouri) also hit the region. Two - four inches fell in some areas, but most saw it as short-term gray hair on top of the pumpkin. For the record, the earliest measured snowfall (0.1 inches) is October 17 - 23 in Missouri urban areas, all occurring in the late 1800s/early 1900s.

The thermometer needle has been pointing down for most of November, and, as shown above, the forecast indicates it will continue that way. Freezing temperatures are expected this evening and, after a short respite this weekend, look to dive considerably early next week. If Monday's low temperatures are really in the low teens and the high doesn't rise above freezing, the end of the season will be here awfully early. Irrigation systems are being blown out across the area, and the last mow and spray of the year may have occurred or will this weekend. In recent years fall seemed to persist until Thanksgiving. In 2019, September was 6+ degrees above normal and October was 3+ degrees below normal. With the end seeming nigh, one might ask if we even had a fall season?

Over the last two weeks, precipitation relaxed for KC and the NW part of the state but cranked up for mid MO, and especially southern MO. Precipitation, the early snowfall and cool temperatures have resulted in unusually wet soil conditions for much of the state. Unfortunately, an elevated risk for flooding is on again for the state since the water has no evapotranspiration escape route. The silver lining may be a reduced risk for winter desiccation for most turfgrasses, but as we learned last season zoysia doesn't respond well to cold and wet conditions.

Dry & Cold Expected

  1. A flip in the persistent precipitation pattern in the KC region. – HPRCC
  2. The fairly. – NOAA


Late Hits

Soil temperatures, which can be viewed here, are plummeting quickly. As the growing season starts to head out of bounds, I often get asked about hitting turfgrass with late management practices and if they will gain yardage or draw a penalty flag. While many of these answers aren't set in stone by research, I've accumulated some of my responses and what the research indicates.

  • Fertilization: This question is probably the most controversial. For cool season grasses, Dr. Beth Guertal briefly reviewed in GCM (Verdure: How Late is Too Late?) a much larger review paper by Bauer et al. 2012. In many respects, the reviews point to the need for further review and research. The potential for N leaching and loss are high since the plant is not metabolizing at a normal rate in cooler temperatures and little research exists on the uptake potential of grasses in cooler temperatures. The advancement of spring greening of cool season grasses is variable depending on species and weather conditions. Last but not least, late-fall N fertilization impacts on photosynthesis and rooting also seem to vary considerably. Therefore, a September and October N fertilizer application of 1 lb N/1000 sq ft each may work well in a normal fall for recovery and extended color. If these aren't down by now though, falling soil temperatures and a cold forecast won't provide much benefit in a "catch up" application.

    Potassium as a warm-season "winterizer" is another controversial topic, and considering last year's zoysia winterkill event is on the forefront of many minds in the region. On bermudagrass, a paper entitled Potassium fertilization related to cold resistance in bermudagrass by Miller and Dickens 1996 does not indicate a relationship between lethal temperatures on 'Tifdwarf' and 'Tifway' bermudagrass and higher K rates and leaf tissue concentrations. Their recommendation is to simply supply the plant with adequate K. No similar study could be found for zoysiagrass. On the flip side, the mantra is that fall N fertilization of warm season grasses will decrease cold hardiness. Several researchers including Goatley, Schmidt and Chalmers, Richardson, and Munshaw have demonstrated no effect of fall N on bermudagrass winter tolerance. This obviously doesn't mean to go out and fertilize dormant turfgrass, but September or early October is not the evil it once was thought to be. In an anecdotal observation from last year, bermudagrass that was not fertilized over the summer with nitrogen was susceptible to more winterkill than fertilized areas. No similar research was found for zoysiagrass.


  • Zoysia Recovering from 2019 Winterkill: If new zoysia sod is still coming on and remains thin, many superintendents are protecting the investment with a sand topdressing layer. While rooted in anecdote rather than science (pun intended), courses on a consistent sand topdressing program did appear to have less winterkill in 2019.


  • Seeding: Homeowners with bare areas are still wondering if they can throw seed in this weather and gain cover. That ship has likely sailed. A few years ago, Dr. Brad Fresenburg and I reviewed research by Reicher et al. 2000. They demonstrated dormant seeding of Kentucky bluegrass or tall fescue in November, December or March was effective in reducing establishment time the following spring. Therefore, my recommendation to homeowners is if the they have the seed now throw it now or during a window this winter, and presumably expect to throw it again in April since September was forgotten. For bentgrass seeding of putting greens, the window has passed. In a recent paper by Heineck et al. 2019 that focused more on spring recovery from winterkill and variability in cultivar germination, bentgrass germination overall did not occur below 45 F. Current conditions and the forecast ahead don't provide much hope in that respect.


  • Mowing: Pretty simple, but not completely obvious. The obvious: don't mow when it's frozen. #2: Don't mow unless it's growing. Gas from the mower can likely be drained for warm season grasses and (if mowed recently) presumably for cool season lawns and roughs (except if mulching in leaves - see below). The region may experience some more foliar growth on bentgrass putting greens if temperatures rebound quickly after the mid-November dip. The sand-based system and necessary lower mowing heights makes forecasting when to winterize greens mowers a little more difficult.


  • Leaf Removal: One exception to #2 above is mowing to mulch leaves into a lawn rather than cutting the grass. Leaving leaves over winter to stay wet, shade and smother lawns is a recipe for a thin stand. An extensive review of research from Purdue and Michigan State was authored in 2013 by Fresenburg and Quinn. While C:N ratio and organic matter did obviously go up, multi-year studies showed no adverse effects from chopping up leaves, particularly with normal nitrogen fertilization. In Missouri, we have the advantage that all the leaves normally don't drop at once due to species diversity, although it does seem like most dropped yesterday all at one time in Columbia (perhaps the only true aspect of fall this season.).


  • Dollar Spot: View the Smith-Kerns dollar spot model. The model has crashed below the 20% threshold in most of the state since early - mid October and has been at 0 since Halloween. For the most part, symptoms should be done for the season. If old scars are still present, however, a final application of a strong fungicide should be applied.



  • What to do about late large patch?

    1. Large patch symptoms evident in rapidly browning zoysia.
    2. Symptoms in fungicide evaluation trials without fungicide treatment.

  • Large Patch: Superintendents who haven't made two fall large patch applications are questioning whether they should plan on one now as a catch up. In some cases, they are seeing some breakthrough as the zoysiagrass goes dormant. Research on fungicide applications made to dormant zoysiagrass is scant in the literature, and in all of our trials we have not applied a fungicide in November for control. We have, however, investigated single applications for control and found that an early spring application prior to greenup in early April provides consistent large patch control in spring. Therefore, if an application was missed, perhaps a better makeup treatment would be earlier in the spring rather than now when the plant is going dormant anyway. This recommendation may be tempered in southern regions if considerable activity is still occurring and zoysia is conspicuously thinned. In this case, a spot curative application may be necessary rather than waiting for spring.


Lee Miller

Extension Turfgrass Pathologist
University of Missouri
turfpath@missouri.edu
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