A Step into Spring

Weather

Old Man Winter Ran Warm

Meteorological winter is over and spring is upon us. While the winter of 2020 was disruptive with constant school and road closings from snow and ice, it will not be remembered as bitterly cold. December 2019 was the 10th warmest on record, and a (what has become typical) mild January followed suit to provide the 2nd warmest Dec – January on record. February cooled down somewhat, with the statewide average just a shade over a degree above normal to sweep the three-month winter series. Single digit and below zero lows were the exception, starting early on November 12th, 2019 and recurring only on three other dates in winter throughout the central portion of the state (Jan 19, Feb 13, and Feb 14). By contrast, Columbia experienced seven dates in 2019 and twenty in 2018. This pattern falls in line with our brethren to the south, with many locations experiencing their earliest spring leaf out on record. This has come along with several severe weather events, like the recent tornado outbreak in Nashville. Thoughts and prayers go out to all of those so terribly impacted.

Wet Pattern Continues

Consistent, and oftentimes overbearing precipitation events have been a constant hallmark over our recent weather pattern. Since our drought from April – July of 2018, three-quarters of our monthly rainfall totals in Missouri have been above average, and in some cases shockingly so. This includes the second wettest December – May 2019 span on record and the 8th wettest August 2019 and January 2020. For the year, 2019 was the 7th wettest on record, falling behind just 2008 and 2015 since the turn of the century.

Early Spring Forecasted to Stay Mild

Mild temperatures in the first days of March have put a spring in our step, and the warmth is forecasted to stay well until the Ides. Be aware, however, that the last freeze (< 32 F) for most of Missouri and the region is historically still over a month away (see below). Unfortunately, a rainy pattern is also slated to return in mid-March, when we could use the extra bit of dry time in hopes of avoiding the flooding situation of last spring.

Quick Hits

We’ve received a few samples in the turfgrass diagnostic lab early this year. Most samples are from younger bentgrass greens under covers, which with the weather conditions provided a warm, moist environment and breeding ground for some cool season diseases. One to be on the lookout for these first few weeks of spring is pink snow mold, also known as Microdochium patch. This disease doesn’t shut down when the snow (or textile) cover ceases, as spores of the pathogen (Microdochium nivale) will continually be produced in these perfectly wet and cool conditions. Symptoms can take various forms, ranging from patch-like symptoms, to smaller spots that can appear like dollar spot as shown above, to running streaks with drainage patterns that appear similar to Pythium. In many of the cases, mycelium will be present in the morning and brick-red to pinkish (hence the name) color will occur on the margins of symptomatic areas. During your first weeks of morning mows, instruct your mowers to scout for this disease. Fortunately, several fungicides work well for curative control including a tank-mix of chlorothalonil + iprodione, Fame + C or T, Medallion, Pillar, Tartan, etc. In areas such as the Pacific NW where this disease occurs perennially, research by Oregon State and others has shown iron sulfate and Civitas as effective controls when applied preventively.

Conspicuous but not Strenuous Yellow Patch

Yellow patch has also been reported in a few areas around the state. This disease, caused by Rhizoctonia cerealis, results in conspicuous light straw to bright yellow rings in creeping bentgrass and Poa annua. Yellow patch, fortunately for this region, is more impactful on annual bluegrass. Once temperatures and growth potential of bentgrass rises, this disease normally fades away. Preventive treatments of azoxystrobin and other QoI fungicides in late fall and early winter are most effective. Curative treatments now will be slow to take effect, and rely on warm spring temperatures ahead.

Burping the Babies

Nick White, Carlos Arraya and the good folks at Bellerive CC are taking care of the NTEP warm season putting green trial this week, by removing the straw and cover and “burping the babies”. The plot area looks very good with some green in the green apparent in some of the varieties. The 10-day forecast doesn’t indicate any severe drops into freezing temperatures so these young’uns should get a couple of good doses of sunshine this week and potential rainfall early next week. If (or when) temperatures drop back into the 20s, the cover will be replaced.

Finish those winter/early spring chores. Make sure your mower blades are sharp, and don’t forget to calibrate the sprayer or spreader prior to its first spin. For more information on sprayer calibration and using the 128th method, see this article.

The Status of Spring

The first mowing on many greens throughout the northern transition zone has soon or just occurred, and thoughts of crabgrass prevention and the first mow on higher cut turf are dancing through many spring-filled heads. Spring is the most important time to target the emergence of many turfgrass pests. I, for one, am not likely to handle a serious conversation when I first wake up and haven’t had a first cup of coffee. Most pests rolling out of bed after winter aren’t prepared either. Spring is also a critical window to provide the best possible springboard into summer by maximizing plant health and growth potential, particularly for cool season species.

Similar to last year’s report at this time (click here to view), this is a quick review of how this early spring is shaping up to others, and where to go (other than here) for information on when to pull the trigger on spring prevention.

Soil Temperature

The daily two-inch soil temperature eclipsed 55 F on March 2 in Cape Girardeau, but have just tickled the 50-degree mark for most of the state (except for KC). While trending upwards, the five-day average is still in the mid-40s. In 2019, soil temperatures first crept into the mid-40s in mid-late March. 2018 was similar in early March, with a temperature tumble in April. 2017 was the anomaly with spring (and forsythia bloom) in February, and full-blown plant growth in late March. Therefore, no predictions on the future of the 2020 spring here…

The 55 – 60 F two-inch soil temperature range averaged over five days is an important benchmark to start taking action for prevention of several diseases. This is the target threshold for the first preventive application for fairy ring (with a side of patch diseases and dollar spot) control on sand-based putting greens. On greens, the 60 F 5-day soil temperature threshold is suggested for the start of prevention of Pythium root diseases on putting greens. Based on our earlier research, spring preventive large patch control should be targeted at the latest within this window (outbreaks and less control occurred at 60 F soil temp 5-day average).

The MSU Growing Degree Day Tracker 4.0

I’ve written ad nauseum in past March reports (2016, 2017, 2018, 2019) about this fantastic service provided by the Michigan State University. Version 4.0 is up and running, incorporating a dozen models into the system to serve a large swath of states including KS, MO, IL, IN, etc. For a more personalized service I suggest making a profile and signing up for email alerts here – http://www.gddtracker.net/alerts/view/. For example, the “close” indication for Proxy/Primo spring prevention of Poa annua seedheads was sent via email just yesterday. One of my favorite portions of the site is comparing the current year GDD data to the previous year. As of yesterday, (3/3) the STL region is 90 base 32 GDD and 4 base 50 GDD ahead of 2019.

Frost/Freeze Probability Guide to Guide Planting

Pat Guinan, the weatherman and Missouri state climatologist designed a very useful website that analyzes data from 1981-2010 to determine the probability of a freeze event ranging from hard freeze (24°F) to moderate (28°F & 32°F) to a light frost (36°F). While every spring is obviously different, this site provides an important historical framework for when less hardy plants should go in the ground. For golf superintendents, this information may also indicate a likely date when you don’t have to give the morning call in to your pro shop to hold golfers back for another long sip of coffee in the 19th hole. Also for crabgrass control, the last typically hard freeze (<28 F) will occur 50% of the time in early April or late March for most of the state.

Crabgrass Preemergent Timing

Last but not least, most crabgrass will germinate when soil temperatures at or above two inches are 60 – 70 F. Preemergents need to be applied prior to this window when soil temperature is consistently in the 50 – 55 F range. In the state, Cape Girardeau and Springfield are closest to this range with 5-day averages above 45 F. Judging from the 10–14 day forecast, most of the state should get close to this range by mid to late March, making a split application format critical for control through the season. Other than the MSU growing degree day tracker mentioned above, forsythia bloom can also be used to time the first application. The forsythia outside my window in Columbia is at bud swell, but hasn’t popped into yellow glory just yet.