GOLF: If you use a TDR sensor to measure volumetric water content, what is your target range on putting greens?


Update (8/8/2013)

Preventing Con-Air

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Turf Diagnostic Lab Closed til 8/14

I have another out-of-state conference (last of the summer season) to attend this weekend into Thursday of next week.  This one is the annual plant pathologist society meeting in Austin, TX where it will cool down for us to a pleasant 99°F ...  and don’t tell me it’ll be a dry heat.  Several interesting talks and posters will be given including a new name for the dollar spot pathogen, a potential reclassification of the spring dead spot pathogen, development of markers for specific detection of brown patch pathogens, new information on management of bacterial decline, and my graduate student Derek Cottrill’s work on the impact of pH and nitrogen source on the spring dead spot pathogens.  In addition, we’ve organized a field tour to Barton Creek Golf Resort, Austin Golf Club, Dell Diamond Baseball Field, and the Circuit of Americas race track.  It should be an informative and worthwhile trip, with a side of brisket.  If submitting a sample, send it next Wednesday (8/14) and let me know so I get it fresh on Thursday.       

Same Survey?

We had a programming snafu with the survey question on the site, and the answers didn’t get recorded.  It’s corrected and reposted, so if you answered before (about 10 of you) please re-record your answer.  Who knew % was a special, and therefore a very problematic coding, character?

2013 Mizzou Field Day Recap

Field day recap

The 2013 Turf and Ornamental Research Field Day was held last Tuesday, and, in mirrored contrast to last year, over 200 attendees enjoyed a fall-like mid 70°F July morning.  The morning sessions were filled with informative talks from programs led by Drs. Hank Stelzer, Dave Trinklein, Xi Xiong, Brad Fresenburg, and Lee Miller.   Presentation topics included an update on invasive pests of urban trees, the emerging problem of downy mildew on impatiens, zoysiagrass lawn care, wetting agent use on golf putting greens, and weed and disease management practices.  In the afternoon, groups were led on off-site tours of the Mizzou Botanical Gardens, the newly renovated Columbia Country Club, and the Mizzou Athletic Facilities.  At lunch, a special ceremony was held to honor the retirement of Dave Fore, former company president of Atkins Inc, Missouri graduate, and staunch advocate of the program.  Eleven industry sponsors and sixteen vendors provided crucial support for the event.  A raffle held to support the Lobenstein fund, which provides two $1000 undergraduate scholarships per annum, also earned $860. Many thanks to CAFNR, DPS, the Missouri Turf and Ornamental Council, South Farms, and the Bradford Farm crew for their support of the event.  Also, a big thank you to Joe Herzog, superintendent at Columbia Country Club, Pete Millier, Director of the Mizzou Botanical Gardens, and Josh McPherson, Director of Mizzou Athletic Grounds, for their time and effort in putting on three great afternoon tours. 


Cool August, but no very wet.

Statewide average temperatures came it at 75.2°F, or slightly more than 2 degrees below normal.  Record low minimum temperatures were recorded at several areas around the state on 7/27-29, including a 52°F low in Columbia.  This is in stark contrast to last year’s 5th hottest July, and the first cooler than normal July since 2009.   August is continuing the cool temperature trend with the first six days also coming in at about 2 degrees below normal in Columbia, MO.  The forecasted cool weather trend looks to continue with highs only reaching the high 70’s, low 80s for much of next week.  What does this mean?  Two big thumbs up for cool season turfgrass!
Early August precipitation for most of the state has been far from normal, particularly for those in southern Missouri, and much of Kansas.  Precipitation totals in some areas over the last 7 days are well into the double digits, and are 8-10” above average for the span.  This has led to a state of emergency for some areas of the state included heavy localized flooding and highway closures.  For these regions, it also will yield a few warnings as posted below. 

Quick Hits

  • Wet weather warnings
    • Lawns – Tall fescue: Temperatures should be low enough that even in heavy rainfall areas, brown patch may not rear it’s ugly head.  If you make it past this weekend without incident, then next week’s forecast should keep tall fescue in the clear.  Now keeping up with mowing fat, happy tall fescue may be another story.  With these cool temperatures, we are getting some questions regarding fertilizing and renovating now.  We are suggesting to hold off for just a bit, as it is still August after all.  If we get to the end of next week and the 10-day looks as good as it does now, we may be able to get things going early.  If a complete renovation with existing vegetation removal planned, this is the time to start removing that vegetation.    
Very early large patch symptoms on MU research plots.
    • Lawns, Golf Fairways – Zoysiagrass:  Believe it or not, we are seeing some large patch start up here at the turf farm in the first few days of August.  Cool temperatures and ample rainfall shouldn’t make this too much of a surprise, and we should be the first reported since we artificially inoculate and have tons of disease pressure (see pic from 6/6 update).  I anticipate this early disease period to continue with the forecast, but unless the damage is very severe, I advise holding off on a preventive fungicide application until early September when control may be extended into early spring 2014.  I also advise not fertilizing zoysiagrass at this time, and unless some hot weather returns, not fertilizing or aerifying it again for the rest of the year.

    • Golf greens – Pythium root rot, take-all patch, algae, water-logged roots.  I have observed considerable take-all patch mycelium in weak roots, and even more concerning in upper stem and crown tissue in samples over the last few days.  Although I normally consider this a weak, secondary pathogen, (Gaeummanomyces graminis for those keeping score), it should very pleased with these cool, saturated conditions.  Additionally, Pythium root rot, although I haven’t seen it in many samples as of late, could make a comeback with all of this free water.  Remember, it’s a misnomer to think that Pythium root issues only occur in hot weather.  With the extensive variety of species involved, the disease really only needs a pool (aka south of I-70) to swim in.  If targeting either of these two diseases, remember the fungicide must be watered-in to be effective.   Lastly, I anticipate quite an uptick in algae on greens south of I-70 with all of the rain.  Consider a Daconil Ultrex and/or Mancozeb application to tame populations
Early anthracnose symptoms observed on green in mid MO.
  • Early anthracnose symptoms:  On a ‘Penncross’ putting green in mid MO, the very initial stages of basal rot anthracnose were noted in an area of chlorotic and thinning turf. Anthracnose symptoms are normally associated with hotter temperatures, but in my experience I’ve also noticed basal rot anthracnose seems to hit near the end of summer when temperatures dip a little.  In this case, the superintendent caught the outbreak very early in the infection before any significant decline occurred.  I tend to shy away from the DMI fungicides during August due to PGR effects, but if these cool temperatures continue they may be an option.  Strobilurin fungicides and thiophanate methyl are also options but fungicide resistance to these chemistries in some anthracnose pathogen populations may be an issue.  Briskway fungicide, a mixture of azoxystrobin and a new DMI fungicide with little or no PGR effects, may have a logical fit for targeting anthracnose in this application window.  A mixture of a contact (chlorothalonil, Medallion, Affirm) with a systemic and a small shot of nitrogen should yield good curative control and quicker recovery. 
  • I’ve observed a few minor breakthroughs of fairy ring on greens in the past few weeks after preventive application of the two DMI fungicides in the spring.  In landscapes, fairy rings are busting out all over this year, and this current weather conditions are favoring the fall fruiting basidiomycetes much earlier.  I presume these breakthroughs are a consequence of a very wet spring and perhaps losing some of the residual efficacy of the fungicide, and the very high fairy ring pressure.  Now, fairy ring control with fungicides should center on flutolanil (ProStar), azoxystrobin (Heritage) or pyraclostrobin (Insignia) watered-in and tank-mixed with a wetting agent.    

Preventing Con-Air

Prevent Conair from golf greens and other turf areas.

“If pro- is the opposite of con-, then progress must be the opposite of Congress.”  - Gallagher

The above joke from the fruit-smashing comedian Gallagher is one of my favorites, which somehow made me think of one of my less favorite movies “ConAir”, which somehow made me think of several of the samples from putting greens that have come into the lab in the past few weeks.  Let me explain…

Despite the cooler than normal temperatures, several samples of putting greens have been submitted lately with symptoms of physiological root decline (short, sloughed roots, darkened vascular cylinder, etc.).  Invariably, these soil profiles have a large amount of organic matter in them, particularly in the top inch due to degrading leaf matter, declining roots, etc.  This layer can be very dark, and have some plasticity to it – I’ve referred to it recently as “Satan’s spent chewing gum”.  Some also have layering throughout the top few inches of the profile, which acts as several different stop lights for water, nutrients, and fungicides.  In most cases, take-all patch and/or Pythium root rot are also present in these samples, but are acting as secondary pathogens and simply taking advantage of the hospitable moist environment and weakened roots. 

The other similarity between all of these samples is that the soil profile is invariably WET.  The organic matter in the top inch naturally acts as a sponge and holds water up in the upper soil profile.  Conversely, the organic matter barrier doesn’t let the water evaporate out from below either.  We know that roots don’t grow well through a waterlogged soil, but the problems with too much water are not always detailed.  The first problem, of significant issue on golf putting greens, is that water holds heat.  Although it’s not particularly hot now, when water in soils does heat up, it maintains that temperature for a much longer amount of time.  At night, soil temperatures with predominately air in the profile drop rapidly and allow heat- stressed roots a break.  In a saturated rootzone, soil temperatures drop much more slowly, the roots don’t get as long of a break and can’t function properly.     

The second and most egregious problem with a high organic matter, saturated soil is the water replaces the air in pore spaces, and kicks of a “con-air” or anaerobic cycle.  Roots respire, need oxygen, and kick out carbon dioxide.  Carbon dioxide replaces oxygen and can builds up to toxic levels to inhibit root growth.   In addition, the most effective organic matter degrading microbes (fungi and bacteria) are aerobic, so more organic matter than usual builds up due to more root decline, which then holds more water.  Anaerobic bacteria begin to predominate in the microbial population once the oxygen has been taken out of the picture, and produce root-toxic sulfur byproducts (stinky) to continue the downwards slide of organic matter accumulation.  The whole cycle just repeats but never rinses. 

So how do we get to be “pro-air”?  A good portion is to go con-water filled pore space, and I discussed TDR usage briefly in the last update for golf superintendents to get a handle on how much VWC is in the green. We should also glance over the fence at the practices of our farmer friends.  Most farmers till the soil, which eases seeding and removes compaction, but also importantly tills in air - allowing for a drier soil which will heat up quicker and provide the spring soil temperature necessary for seed germination.  As a side note, even some no-till farmers are starting to use gadgets to brush away residue or even till just down the row to achieve these benefits. 

As turf managers, we don’t have the luxury of starting anew each year and destroying our turfgrass stand with tillage… but we can punch holes

  • On putting greens, where stress is high and damage thresholds are low, it should be done often.   In my opinion, at least once with a core every year, and at least every 2-3 weeks with a solid, pencil, bayonet, or star tine during the summer stress period.  Also don’t forget a routine sand topdressing program, which dilutes organic matter, provides more pore space (to fill with air), and protects crowns from scalping and high organic matter, potentially pathogen infested, areas.  I often hear superintendents say that turf is too stressed for these two practices during summer, but an aerifier in the morning or late at night can do just as much, if not more, good during summer than a heavy, 200-gallon sprayer.  And that sprayer is out every 7 days.      
  • On residential turf, aerifying once every year or two should suffice, and on this schedule it’s recommended to pull a core and remove the organic matter.  Tall fescue should be aerified in September/early October when turf is growing well, and summer disease activity is in the rear-view mirror.   Add in fertilizer (1 lb/1000 sq ft in September and October), perhaps a little overseeding, and the lawn should be ready for winter.  Zoysiagrass lawns are the exact opposite.  Aerify when the turf is actively growing in June, July or early August.  It would not be advisable to aerify during these current cool temperatures, however, particularly since large patch has been observed active.      

Lastly, for those in southern MO being hit hard with the current deluge of rain, aerifying and attempting to dry out the root zone will help turfgrass considerably.   Of course, don’t get the aerifier out too early and create ruts, but do get it out and get back to a “pro-air” situation.   

Thank you for your support of the program, and have a good weekend.

Lee Miller
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Extension Turfgrass Pathologist
University of Missouri