SURVEY QUESTION

GOLF: Are there problematic plant parasitic nematodes on your putting greens?

Haven't tested
No
Yes - ring
Yes - lance
Yes - sting
Yes - root knot
Yes - combination
Did but controlled with nematicide

Update (8/15/2019)

Pull a Punch?

Printable Version [PDF]


MU Field Day Research Booklet
Download at http://turf.missouri.edu/research/2019_Field_Day_Booklet.pdf


Thank you to all of those that came out and celebrated the diverse green industry research we had to offer at field day! From trees to weeds, to billbugs, diseases and bees, we covered quite a bit of ground. We appreciate all of the vendors, sponsors, and cooperators that helped us make the event possible, and all of the attendees that made it a success!

A special thanks also to all of our presenters, including those that put in double time to lead afternoon workshops. The tours given by Dave Trinklein, Josh McPherson CFM, and our program were very well attended. Hope to see some of those in our afternoon lawn care program again at our upcoming lawn care workshop series (more details and schedule coming soon).

Weather

August 1st Half Temps a Little Above Average

  1. Temps thus far are running just like summer should. – Missouri Climate Center
  2. Summer temps set to make a come back next week. – NOAA

Except for a couple of lapses, (like today and yesterday), summer heat and humidity have been the rule over the last few weeks. So far in August, temperatures are approximately average to a little below average over much of the region. Expect temperatures to remain summer-like over the next week, so no break for summer stress and cool season turf disease activity quite yet.

Rainfall has been sporadic to start the month, with intense rainfall occurring just across the Missouri borders in eastern Kansas and western Illinois. Some areas in Missouri are actually drying out a bit, with tall fescue lawns going dormant in some locales. An intense system is slated to hit near Kansas City and NW MO tonight and tomorrow, resulting in high rainfall amounts and chances for localized flooding and high winds (see below). Rainfall chances for the eastern portion of the state rise next week in the longer range 6-10 day forecast.

Forecasted Rains on the Way

  1. Heavy rains expected tonight and tomorrow in NW MO. – Missouri Climate Center
  2. Rainfall chances shift east next week. – NOAA

Quick Hits

Summer Issues on Bent

  1. Difference between healthy root (background) and sloughed off root in front.
  2. Pythium oospores set in battered roots.
  3. Infection cushion of summer patch on root vascular tissue.
  4. Basal rot hitting a bit higher at the crown of this 'Penncross' bentgrass plant.

  • Bentgrass Putting Green Diseases: Several samples over the past few weeks had the normal assortment of diseases compounded, and in most cases, preceded by the physiological decline of the root system. I discussed this ad nauseum in the previous report, so won't belabor all of these issues again. Basal rot anthracnose on bentgrass is a relatively new arrival, however, observed in a sample from western Illinois and on our 'Penncross' research green at the farm. This disease can easily be misdiagnosed as Pythium root rot, nematodes, or a bevy of other issues, but the key is to use a 10x hand lens to look for dark discoloration around the plant crown as shown in picture D above. Susceptible bentgrass cultivars include 'Penncross', 'Pennlinks', 'SR1020', and as we saw last year 'T-1'. As mentioned in previous reports, consider raising nitrogen rates a smidge since anthracnose is a low N disease. Consider mixing a contact fungicide such as chlorothalonil (i.e. Daconil) or fludioxonil (i.e. Medallion) along with a systemic like an SDHI, QoI, DMI or combination fungicide.

  • Nematodes on Bentgrass Putting Greens: If you've had issues in the past on putting greens, consider sampling in the next few weeks to determine your current populations and evaluate your control measures. Visit SCN Diagnostics here for more information.

Tall Fescue – Knock Brown Patch Down or Wait it Out?

Brown Patch - Disease of the Year

  1. Brown patch has been prevalent in tall fescue lawns this year.
  2. July 16: Drone photo showing extent of brown patch damage in inoculated plots.

Last year anthracnose on bentgrass putting greens took the prize for disease of the year, and brown patch on tall fescue is vying for the crown in 2019. Buoyed by saturating rains in April and May and resultant high humidity, brown patch has ravaged lawns in the area. Now that we've made it to August and the glories of September are in our sights, what should the strategy be going forward?

Complaints of brown patch occurrence are still coming in from lawn care companies, homeowners, and other professional turfgrass managers that manage tall fescue in golf roughs, cemetaries, etc. In our research plots, some cool nights have reduced the severity of the disease considerably, and tall fescue has recovered from July outbreaks fairly well. If current symptoms are fairly new and not exceptionally severe, allocating resources now towards September aerification and overseeding may be a wiser investment. This does come at a risk of more bermudagrass encroachment into brown patch affected lawns, so if you have that risk you may choose to continue brown patch control measures to stave off bermuda competition.

Brown Patch vs. Gray Leaf Spot

  1. Brown patch lesions will have a tan interior and not a distinct pattern on the leaf.
  2. Gray leaf spot lesions will be distinct spots or will "run" or coalesce.

Another confounding issue over the last several years has been the sporadic arrival of gray leaf spot on the Missouri scene, particularly in St. Louis, Columbia, and Springfield. August and early September is the time to scout and be aware of the potential for gray leaf spot, and not misdiagnose it as brown patch. Invest in a 10x hand lens, and closely examine areas around the margins of tall fescue decline. Brown patch should occur mainly in patches in the stand, and newly infected leaves should have a lesion with a brown margin and light tan interior. Conversely, gray leaf spot may occur spotty in the landscape, or in extremely intense cases as a widespread blight. Newly infected leaves will have distinct spots for lesions that have a grayish interior (no kidding) and a very dark, nearly black margin. Spots can coalesce to run across the leaf blade, but will be more curved than brown patch lesions.

The kicker with gray leaf spot is that control relies on thiophanate methyl and not azoxystrobin as with brown patch. The longest and most effective control is a tank-mix of thiophanate methyl and azoxystrobin. The second kicker is that gray leaf spot likes to dine on seedlings, so tall fescue that is planted a little too early in late August or in a warm September (which unfortunately happens) is especially susceptible. A third problem is the gray leaf spot pathogen sporulates heavily and therefore can move quickly. Monitor for the disease aggressively, and don't overwater and spread spores needlessly.

At this point, gray leaf spot in Missouri is not a perennial occurrence and therefore preventive thiophanate methyl applications in all, but very high amenity tall fescue areas with a history of the disease, are not warranted. As stated above though, monitoring and early detection is crucial, so if in doubt sending a sample into a diagnostic lab isn't a bad move.



Lee

Lee Miller
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Extension Turfgrass Pathologist
University of Missouri