Red October Expected to Continue
Fall began as an Indian summer with a warmer than normal September, and has followed suit throughout early October. Temperatures throughout the state are 8-11 degrees above normal thus through October 9, and withstanding today’s current cool down look to get warm again into this weekend. The current longer term 8-14 day NOAA forecast indicates continued warmer than normal temperatures, which would make October 2017 eerily similar to the last - the 10th warmest October on record and the hottest since 1971.
Increased rainfall events in October are a welcome change from September’s drought pattern. September ended with deficits ranging from 3-5 inches across much of Missouri, so the current rainy pattern of early October (1-2 inches over much of the area) are helping. As noted below, the rains should help out with cool season turfgrass seeding, which was difficult with the lack of rainfall. As with the warmth, the trend of increased rainfall also looks to continue in the 8-14 day NOAA forecast.
October Rain Replacing Sept Deficit
Disease Pressure on Bentgrass Persists
Spider Webs Can Cause Unnecessary Fright
I do appreciate the nice right angle though.
Prevention of Large Patch & Spring Dead Spot
Soil temperatures are down at or just below the threshold range of 70 F for prevention of large patch on zoysiagrass and spring dead spot on bermudagrass. In addition to Columbia, (shown above) five-day averages are currently at 65, 70, 71 degrees F in Kansas City, Springfield, and St. Louis respectively. This cold front pushing through will cause all of these to dive below 70 today, the signal for prevention of these warm-season diseases next spring. So, if not this week than next week applications should be planned on sites with history of these diseases.
For spring dead spot, a two-application approach is advised with the first being made now and the second made 21-28 days later. Recall, last fall above average temperatures extended well into November, and this current and forecasted weather pattern is eerily similar to 2016. Some bermudagrass managers applied fungicide applications in early September and October 2016 and experienced damage from spring dead spot April & May 2017. Even if an application is already down, don’t make the same mistake again by relying on a final fall application in early October. Instead make a late October, or even early November application according to the weather conditions and the stage of bermudagrass dormancy. Bermudagrass plots at the MU turf farm are still very green and actively growing. As for fungicide choice, the newer SDHI chemistries, including penthiopyrad (Velista) and isofetamid (Kabuto), have worked well in our trials for control of spring dead spot caused by O. herpotricha on sports turf height bermudagrass.
Large patch control is a bit more complicated, considering active outbreaks have been occurring in some areas since late August – see previous update. Earlier curative applications aside, soil temperatures are now in a good range to attempt prevention of early disease outbreaks next spring if employing a two or three application control strategy. As mentioned previously, however, a fall application or two is often unsuccessful in carrying the load through the following spring (it is a completely new year after all…). Therefore, an application now combined with an early spring application is often necessary on high amenity zoysiagrass areas. If only one fungicide application on a site with large patch history is planned, then let it go for now and come back next spring to prevent the disease for a longer period during a more crucial stage of the season.
Follow on Twitter! @muturfpath
Like on Facebook! Mizzou Turfgrass
Extension Turfgrass Pathologist
University of Missouri