Lawn Dormancy Looms
MU Turfgrass & Landscape Field Day - August 1
More Fraze Research Underway
- Zoysia with previous large patch symptoms being frazed.
- More fraze research on bermudagrass afflicted with spring dead spot.
Preparations are in high gear for the upcoming field day. As shown above, we initiated new research plots to investigate the influence of fraze mowing and interseeding of cool season turfgrass on disease severity and quality of zoysiagrass and bermudagrass. Many thanks to Perfect Play Fields and Links for loaning us the unit to install this research, and for the expert operation of Daniel Earlywine and Dr. Brad Fresenburg. This project is the brainchild of Daniel’s, who will be discussing and introducing this research at field day.
If curious about this research, (and who wouldn’t be!), register and attend the MU Turfgrass and Landscape Field Day. Registration is open and the schedule is set - http://mufieldday.org. Come on out August 1 to our research facility at South Farms, and we’ll give you the latest on this research and other regional topics of interest.
For more information, feel free to contact me at email@example.com or Kevin Dern at firstname.lastname@example.org. Look forward to seeing you there.
- Summer arrived over the past week. - Source: Pat Guinan
- It doesn't take long in summer to go from saturated to dry. - Source: Midwest Climate Center
Summer’s heat is here in full force, and looks to stay for a while. High temperatures have breached the mid 90s in the last two days with heat indices (which take into account the high humidity) well into the 100s. Evapotranspiration rates are in the 0.25-inch range over the last 4 days, and would be worse without this uncomfortable humidity from southerly Gulf air. Â Water is going fast, however, and non-irrigated tall fescue and Kentucky bluegrass areas are going dormant quickly. Some of these areas may have root systems that are compromised from flooded conditions earlier in spring, which will result in a quick dormancy flash. Just a few hundred miles to the north of us, historic floods have hit the Wisconsin and Chicagoland area. Interesting how much difference a few hours drive north can make in weather.
After a mild blip in the next few days, the heat is unfortunately forecasted to stay and even intensify into next week. The region is in a make or break kind of scenario over the next two weeks. No rain over this timeframe will drive the area into a mild to even moderate drought situation.
6 - 10 d outlook: More Red on the Way
- Heat expected to hang on through the middle of July - Source: NOAA CPS
- Over July 19-23, no real idea in forecasts how much rain may fall. - Source: NOAA CPS
Anthracnose - We have observed more basal rot anthracnose on golf putting greens this year than any I can remember in the past. Four samples from bentgrass putting greens have been diagnosed with the disease in the last two weeks, and I’ve been posting about it since late May (see the post here). To check suspect areas yourself, invest in a 10X hand lens, pull a core, and look at the crowns of declining bentgrass for the jet-black structures above. Wet weather and wild temperature swings are the probable cause for this increase, but it should also be mentioned that anthracnose resistant to both the benzimidazole (thiophanate-methyl) and QoI (azoxystrobin) chemistry has been found in other areas of the country. Do not rely on these chemistries solely for control, and rotate in the DMIs or Civitas (careful during high temperatures), Velista, and other fungicides for control. Bentgrass that goes into drought stress is more susceptible, and conditions will be ripe for that. Also remember anthracnose is a low N disease so don’t forget to feed the beast. For more best management practices related to anthracnose control, see the guide produced by the Rutgers research team here.Â
Post Application Irrigation = Soilborne Disease Control - My colleagues at North Carolina State are proofing this equation through sound research.Â At a time when summer patch is nibbling on Kentucky bluegrass and creeping bentgrass roots and nematodes and Pythium root rot are working in the greens profile, this is a valuable and critical point. Hear the message and see the proof in the NCSU turf pathology article here.
Anthracnose on the Attack
- Since late May, anthracnose symptoms are showing on susceptible bent varieties.
- Black rot at the crowns is a characteristics symptom of anthracnose basal rot.
Leafhoppers on Tall Fescue - Dr. Brad Fresenburg pointed out last week that, along with the obvious spike in Japanese beetles this year, there have also been an incredible amount of leafhoppers in lawns. I, too, have noticed quite a bit in my lawn as well as the lawn mower or kids flush them out of the canopy. Interestingly a previous study in tall fescue pasture fields identified 54 different species from 37 genera in the leafhopper family (Cicadellidae). Leafhoppers, like aphids and chinch bugs, are "yellow bellied sap suckers", feeding on plant juices sucked from the stem. Lawns should be able to sustain a very healthy population of leafhoppers, and although it may turn tall fescue a little brown, they shouldn't result in any sustained injury requiring treatment.
Another PSA to please poke holes in putting greens. Roots will thank you for it.
Lawn Dormancy Looms
Localized dry spot on bentgrass putting greens has been occurring sporadically over the last few weeks, but really took hold over the past week. Water needs to move in a constant and even flow through the soil profile, and not a preferential flow from water repellency caused by organic acid accumulation. On greens, surfactants may be necessary to keep this consistency.
This localized dry spot may be a precursor to significant drought dormancy on commercial and home lawns. Remember that tall fescue is more deeply rooted, and goes into and, more importantly, comes out of dormancy well even in extended bouts of drought. In the 2012 drought, tall fescue that wasn’t watered inconsistently and incompletely recovered well. Similarly, zoysiagrass should do just fine with a little less water than normal and will usually pop back to green when rainfall returns.Â Monitoring for insect activity on zoysiagrass during this period will be important, however, to assure that the brown is not due to chinch bug or billbug activity. Kentucky bluegrass and perennial ryegrass will suffer without some irrigation, although newer cultivars of Kentucky bluegrass have shown much better heat and drought tolerance.
If a commercial or home lawn is to be irrigated, (which as stated above is often not necessary for survival) please remember to water early in the morning for these reasons.
- In the morning, winds are normally calm so the distribution of water is maximized.
- Evaporation and evapotranspiration is also at it lowest. The sun’s rays will not yet bake the water back into vapor or boil it in your rootzone. Soil temperatures may be kept lower for a bit longer with the cool morning drink.
- Perhaps most importantly, foliar diseases such as brown patch and Pythium may be limited with this practice. Brown patch needs approximately 9 hours of leaf wetness to spark, and Pythium blight needs approximately 13 hours. If irrigation occurs at dusk, the leaf wetness period begins and only ends when the subsequent nighttime dew burns off with sunlight the next morning. Conversely, watering in the morning rinses off the night dew and may actually disrupt the movement of the pathogens which is leaf to leaf via mycelial growth.
Easy math. Water at 7 pm and the leaf stays wet until the sun bakes it off (if lucky) by 8 am. Thirteen hours. Dew sets naturally at approximately 10 pm and irrigation occurs around sunrise at 6 am. Eight hours. Water early in the morning. The early bird really does get the worm.
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Extension Turfgrass Pathologist
University of Missouri