Double, Double Toil & Trouble. Weather. SIGN UP NOW: MU Turfgrass & Landscape Field Day - August 1

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Timothy Allison
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1 SIGN UP NOW: MU Turfgrass & Landscape Field Day - August 1 Field day is right around the corner on Tuesday, and preparations are in high gear or low gear when working in last week s heat. The forecast looks about as good as possible for the first of August, with highs in the mid 80s, dry and low humidity. Even better this weekend looks to be a big break for cool season turfgrass, perhaps you d also like to take a break with us and learn about our cutting edge research. With our fraze mowing research I highlighted in the last update, this is indeed an intended pun. Registration is open at for both attendees and vendors. We hope you can make it out to enjoy the fine weather for the August premier, as we ve got a ton to share. Nematodes, soil sampling, fungicide resistance, weed control, hydrophobicity, and various others. If you or a friend want to learn about going native, (no pun intended), we even have a concurrent workshop geared solely towards that subject (click here for more information). Make your friend drive For more information, feel free to contact me at turfpath@missouri.edu or Kevin Dern at mufieldday@gmail.com. Look forward to seeing you there. Weather Wow, what just happened. Summer went from a modest mouse to a roaring opera singer last week, hitting a crescendo of 100+ degree heat and humidity that sent feel like temperatures near F. Nighttime temperatures also were astonishingly high. At 10:30 pm on Saturday night readings in Columbia were still 87/feel like of 100 F. The last

time heat occurred like this in Missouri was 2012 during the same July 16 22 period. Mark your calendars, that is evidently the top of summer s bell curve.

2 time heat occurred like this in Missouri was 2012 during the same July period. Mark your calendars, that is evidently the top of summer s bell curve. Rain also was fairly hard to come by in July until Saturday, and more disastrously yesterday, when heavy downpours (some 7 inches) ravaged the Kansas City area and caused serious flooding. For those affected, hopefully the damage is not long lasting, and your minds can return back to turfgrass soon. In St. Louis, the rains have been brief, and deficits are nearing 2 inches for the month of July. On the bright side, the forecast looks great. Highs in the low 80s and lows in the 60s are set to return. Gasp. Not to jinx it but we could also see a dip into the high 50s this weekend, which is a much needed break for very tired bentgrass putting greens and cool season sports fields and lawns. Continued dry weather is expected, however, which will be a relief to those in KC.

Quick Hits Basidios Bubbling The high temperatures and sporadic rain over the last 10 days has both fairy ring and brown patch humming on tall fescue lawns and creeping bentgrass putting greens.

3 Quick Hits Basidios Bubbling The high temperatures and sporadic rain over the last 10 days has both fairy ring and brown patch humming on tall fescue lawns and creeping bentgrass putting greens. Both of these pathogens belong to the basidiomycete group of fungi, which is most famous for producing the mushrooms on your pizza (hopefully this isn t the only type that s found its way on your plate). In the case of both of these diseases, once they really start firing, they are difficult to curtail. For brown patch, particularly on tall fescue, azoxystrobin has consistently worked the best in a curative situation in our trials. Fairy ring, a soilborne pathogen, is more difficult to control curatively and requires a watered in fungicide + wetting agent combination after symptoms appear in the summer. The SDHI fungicides such as flutolanil and penthiopyrad have worked well in our trials curatively on greens. This being said, once you get these issues in summer on weakened cool season turf, it will take a while for recovery.

4 Chill out on cool season lawns. They ve been going through a time, and need their expectations lowered a little. Homeowners, particularly in STL, have been lighting up the help line in the last two weeks wanting to know what magical concoction they can spray to fend off brown patch, Pythium and every other disease they can point at. While these diseases are active, for the most part the brown that is most oft seen is simply caused by heat stress and drought dormancy. Rather than spray a fungicide at this point in the season, consider buying seed that can be sown in more suitable September weather. Remember, tall fescue is tough. The species can take a droughty beat down like in 2012 and come back in fairly good form if allowed to go brown. Don t mow if it isn t growing. When you need to mow make sure the height is at least As for the picture above, this odd pattern is due to ground cracking and compaction, and the preferential flow of water (and roots) into those cracks preventing drought dormancy in scalloped lines. Probably a good sign that an aerifier should be run across the area in fall. Anthracnose, anthracnose, anthracnose. Epidemic year for this disease (see last four updates). Four more samples in the last two weeks from susceptible bentgrass putting greens ( Pennlinks, 2 x Dominant, and Penncross ) from all over the state. Do not rely on QoI fungicides (i.e. Heritage, Insignia, Fame, etc) or benzimidazoles (i.e. thiophanate methyl) for control as resistance can, and may be developing in these pathogen populations. New SDHI fungicides such as penthiopyrad, and rotating in older DMI fungicides sparingly or the newer less growth regulating DMI difenconazole is advised.

Fire Burn & Cauldron Bubble No quote other than Shakespeare s opening witch chorus from Macbeth could describe the weather of the last 7-10 days, and the impact it had on bentgrass putting greens.

5 Fire Burn & Cauldron Bubble No quote other than Shakespeare s opening witch chorus from Macbeth could describe the weather of the last 7-10 days, and the impact it had on bentgrass putting greens. These impacts were most severely felt on greens that hadn t been vented regularly and those with soil profiles with too much organic matter and/or too much water. The soggy hot root syndrome (SHRS) was back and with a vengeance in the last two weeks. The weather was perfectly set for it too, as high temperatures boiled water from below and high humidity didn t let it escape from above. Indeed much like a witches brew. Particularly for those in Kansas City and other areas affected by heavy rains, venting as aggressively as possible during the cool down will go a long way when August comes back into its normal form. On tucked greens, fans may be necessary to move stagnant, humid air, and as previous research by Han et al. from Auburn University showed, critically reduce soil temperatures. Sub air type units to pull or push air should be employed, and even back back blowers plugged into some drainage lines may help. Even if using a soil moisture meter to water to a certain VWC %, take a soil core or two a few times a week to determine if water is moving below the tine depth. Use your nose. Give those lower regions of the soil profile a smell. Assess if a sulfur odor producing black layer is forming at any depth in the rootzone, indicating stagnant water anaerobic conditions toxic gas accumulation. For a flash back on this same theme, I wrote similar articles during this same time last year (June 28, 2016 Disease Update) and one a little later (September 8, 2016 Disease Update).

6 Lee Miller Follow on Like on Facebook! Mizzou Turfgrass Extension Turfgrass Pathologist - University of Missouri

Lawn Dormancy Looms. Weather. SAVE THE DATE: MU Turfgrass & Landscape Field Day - August 1

Lawn Dormancy Looms. Weather. SAVE THE DATE: MU Turfgrass & Landscape Field Day - August 1 SAVE THE DATE: MU Turfgrass & Landscape Field Day - August 1 Preparations are in high gear for the upcoming field day. As shown above, we initiated new research plots to investigate the influence of fraze