Mizzou Field Day & Lobenstein Golf Tournament
– One Week Away: July 21, 2015
Make plans to join us next Tuesday, July 21 for the MU Turfgrass & Ornamental Field Day. Below is just a small smattering of the educational reasons to attend.
- Planning to renovate? See the latest NTEP turfgrass trials including creeping bentgrass (both greens and fairway height), fine fescue, bermudagrass, and zoysiagrass.
- Feeling the fraze? Observe fraze mowed research plots three weeks after to gauge recovery.
- Have insect prone zoysia? Hear the latest on billbugs from Dr. Xiong’s research program.
- Got brown patch or large patch? Learn the recent research results from our program on the best way to combat these two diseases.
- Curious about new fungicides on putting greens? Listen to our experience with using these products in our trials.
- Got trees? Hear the latest threats to tree health from MDA State Entomologist Collin Wamsley.
- Have staff that need to learn sprayer calibration, or need a refresher yourself? Dr. Brad Fresenburg will demonstrate an easy step-by-step process to keep your applications precise.
- Got wet plants? Dr. Dave Trinklein will discuss the recent wet weather woes and how to prevent loss.
In addition to all that education, we also will be holding the first annual 9-hole Lobenstein scholarship tournament after field day at Columbia Country Club. For more information on this event, see the flyer below.
To register for field day and the Lobenstein tournament, follow the links below.
The first half of July was extraordinarily cool, and once again wet for large portions of the state. The southwest portion of the state most recently felt the deluge of 2015, with 8-10” of precipitation in Springfield and Branson since July 1. These July rains followed the 9th wettest June on record in Missouri, and the wettest June since 1981. Our neighbors to the east, (Illinois, Indiana, and Ohio) all had the wettest June on record in 2015 with totals more than twice the 20th century average (https://www.ncdc.noaa.gov/sotc/national/201506).
May-June combined was the 5th wettest on record in Missouri, mirroring the trend over the past few decades with only 6 drier than average years in the past 20. Over these past two months, the state has experienced a very odd rainfall pattern that left no portion of the state unscathed. On seemingly 14-day intervals, Kansas City got nailed with heavy rainfall first, followed by St. Louis, and most recently Springfield/Branson. Everyone has experienced super-saturated conditions at some point during this cycle, creating a petri dish for various turfgrass pathogens.
The cool temperatures feel like a year ago now, with consistent 90°F + summer-like highs occurring throughout the region. The 8-14 day forecast indicates the warm temperatures will continue, along with an anticipated dry-down period (thank goodness). With the heat, underlying saturated soils will create substantial humidity and the potential for considerable turfgrass disease activity.
- As in the southeastern U.S., (click here to view report from NC State University) summer patch has been diagnosed on samples of both Kentucky bluegrass and creeping bentgrass in the last two weeks in Missouri. The pathogen (Magnaporthe poae) begins infecting roots, stolons, and rhizomes in spring when soil temperatures reach 65°F. In areas with a history of the disease, the first preventive fungicide application should be targeted to the 65°F infection period, with 2-3 subsequent applications planned on a 21-28 d interval. Curative fungicides are less effective. The strobilurin or QoI fungicides are recommended for control, and all applications should be watered-in with 1/8-1/4” of post application irrigation. A light application of ammonium sulfate (0.2 lb N/1000 ft2) may also aid in recovery.
- A small spot of Pythium blight was first observed today on an inoculated creeping bentgrass fairway, indicating environmental conditions are now ripe for occurrence of this disease. In this region, the disease is most prevalent on turfgrass seedlings, higher cut bentgrass and Kentucky bluegrass used on sports fields (particularly baseball infields). Pythium blight, a foliar disease, is rarely observed on established (> 2 year old) creeping bentgrass greens, but root issues caused by Pythium spp. are the very current and normal culprit of decline. High heat and high humidity over the next week will continue to favor this disease, which can move rapidly in a turfgrass sward and cause considerable damage. Methods to reduce foliar leaf wetness will help limit this disease, including dew whipping or pulling hose, irrigating or mowing in the morning, reducing morning shade or increasing air movement. Pythium spp. are not true fungi, so the most effective fungicides for control are in different classes than most others. Preventive applications on high amenity turfgrasses may be warranted.
- Fairy rings are occurring throughout the region. Fairy rings are formed by basidiomycete fungi (i.e. puffballs or mushrooms) along the subsurface fungal colony where mycelium density is greatest. In most instances, we are currently observing lush green (or Type II) rings, the result of plant available nitrogen (ammonium) formed from fungal thatch degradation. If the fairy ring fungus starts growing too aggressively, decline may occur from ammonium toxicity and/or soil hydrophobicity. Most problems occur on golf putting greens, since organic acids released by fairy ring activity can coat sand particles and render them water-repellant. Curative control relies on both controlling the fairy ring fungus and remediating soil properties. Aerify affected areas to break though the water repellant layer. Water-in (1/8 - 1/4”) a soil surfactant + fungicide tank-mix to deliver the fungicide to the target rootzone. Flutolanil (ProStar), azoxystrobin (Heritage), or pyraclostrobin (Insignia) are most effective for curative control. If fairy rings on greens are a perennial problem, consider applying fungicides preventively next spring (click here to review this application strategy).
Wet Wilt/Physiological Decline of Putting Greens
At one point or another in the last 6 weeks, root growth in Missouri and much of the Midwest has been limited due to saturated, anaerobic soil conditions. If high temperature and humidity occurs as forecasted, the weather pattern could provide a one-two punch resulting in wet wilt or physiological decline on bentgrass putting greens. Wet wilt occurs when root function is limited and can’t keep up with the transpiration needs of the plant. In addition, roots on bentgrass putting greens can cook in saturated soils during high temperature periods. Bentgrass putting greens have a low amount of verdure and are prone to rapid increases in soil temperature. If drainage is compromised or too much organic matter is present holding water, soil temperatures may remain high for extended amounts of time due to water’s high heat capacity. Cooler temperatures have negated most of this stress thus far, but current and forecasted warm temperatures could start a downward slide.
Air movement, cooling, and stress reduction are crucial to mitigate wet wilt or physiological decline. Dr. Peter Dernoeden covers this topic in a fantastic article in the March/April 2006 issue of the USGA Green Section Record (click here to view). For experienced superintendents, the following tenets of summer bentgrass management are common knowledge, but they bear repeating while sitting on what appears to be summer’s doorstep.
- Raise mowing heights, and use solid rollers during summer stress periods.
- Suspend brushing, topdressing, or other abrasive practices on heat-stressed putting greens.
- Consider spray applications carefully, and try to reduce the frequency of driving a sprayer across greens. Remember 200 gallons of water weighs over 1600 pounds, and the sprayer itself may weigh a ton. Using a spray hawk or similar is suggested.
- Vent putting greens often, particularly after rain events and before heat stress events.
- Syringing greens may be necessary to cool greens, but should be done with extreme care as to not wet the root zone. Consider syringe amounts at 1/40” or less, which requires light, brief misting.
- If possible, irrigation amount and scheduling decisions should be made with the aid of volumetric water content measurements.
- Lastly, if you can, use a fan. Air movement across the putting surface can reduce air and soil temperatures by 5-7 degrees (GCM, Han et al. 2006), which can be the crucial difference. If possible, the fan can be on 24 hours a day during these hot, humid periods.
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Extension Turfgrass Pathologist
University of Missouri