Now that nobody is thinking about snow mold, the 2012 UW Snow Mold Reports have been posted online at the Turfgrass Diagnostic Lab’s website in the ‘News’ section on the righthand side (http://www.tdl.wisc.edu/).  Reports and pictures from 2 sites in Wisconsin, 1 site in Michigan’s UP, and 2 sites in Minnesota have all been posted.  Unfortunately, the mild winter led to acceptable snow mold results being obtained only from the Wawonowin site.  The reports will also be permanently housed on the TDL’s ‘Research’ page.

Special thanks to Brian Horgan and Andy Hollman for their help with the Minnesota sites, and also to the following superintendents for hosting both our snow mold trials and other winter research:

• Antigo Bass Lake – Dave Van Auken
• The Legacy at Craguns – Matt McKinnon
• Les Bolstad GC- Brent Belanger
• Odana Hills GC- Jeff Jushka
• Sentryworld GC – Gary Tanko
• Wawonowin CC – Andy Hakkarinen

Please call or email with any questions, concerns, or comments you may have regarding these reports.

Thanks,

Paul
–
Paul Koch, M.S.
Associate Researcher
Turfgrass Diagnostic Lab Manager
University of Wisconsin – Madison
2502 Highway M
Verona, WI 53593
(608) 845-2535
www.tdl.wisc.edu

Check out the two pictures below. The one one the left shows a strip of perennial ryegrass infested with dandelions, but the surrounding tall fescue is dandelion free. The p. rye and t. fescue were planted at the same time and have been managed identically for the past five years. The picture on the right is of a stand of Kentucky bluegrass (left side of picture) next to a stand of tall fescue (on the right). While the effect is less dramatic, it’s clear that the left side has dandelions while the right side does not. I’ve also noticed this effect in my tall fescue lawn – my neighbors have dandelions and I don’t. But I do have plenty of clover, which also has infested the tall fescue in the pictures below.

Yesterday, I asked Paul Koch (TDL Manager) how the soil temperatures may influence timing for control of our early season patch diseases. Here’s what he said (from vacation, nonetheless):

“Though soil temps are in many cases indicating that initial fungicide applications for important diseases such as summer patch, take all patch, and fairy ring should be applied soon I would recommend holding off unless there is recent history of significant infection at the site.  The primary reason for this is the time required for both the plant to begin growing (and exude chemical signals to the fungi) and for the fungus to respond and begin growing and responding to the signals.  The fungi have certainly begun responding, but now that temperatures have moderated any growth or infection by the fungi has likely dropped considerably.  If a fungicide application has already been made, be prepared to make additional applications in the coming months.”

Just wanted to share the soil temperatures at the O.J. Noer Turfgrass Research and Education Facility (Verona, WI) with everyone.

How amazing is it to see the soil temperatures go from frozen on March 7th to over 50 degrees on March 16?  We sustained temperatures above 50 for 10 days, and have now dropped below 50 degrees at two inches. Crabgrass germinates when soil temperatures are around 60 degrees. The soil temperatures from the Noer are taken under a dense Kentucky bluegrass lawn, but in areas where crabgrass is normally problematic (bare soil, near concrete, etc.), the temperatures were probably 2-5 degrees warmer - enough to start the germination process.

So how will this up and down roller coaster of soil temperatures affect crabgrass pressure in Wisconsin? I wish I knew. Crabgrass may have germinated in some areas, but may not have in others.  An herbicide with both pre- and post-emergent activity will be the safest bet in these uncharted waters.

Doug

Well, I took a guess on my last post that the GDDs were going to be off this year. For Southern WI, at least, I’d like to retract that. The picture below shows the Forsythia right outside my office in full bloom, with soil temps around 55 F and the GDD model says we are in prime time for crabgrass prevention – so all is well there. The 15 day forecast shows highs in the 70s all this week, and then dropping to the 60s and 50s for next week. These temperatures will not put a damper on the current green-up and bloom. That puts us into April, where cold temperatures are not likely to linger very long if they even show up. I’m not sure what’s going on in Northern WI, but it looks like Southern WI will have an entire month longer growing season this year.

It’s not even St. Patty’s day and the growing degree day models are starting to light up all over Southern Wisconsin. Because the season has been so unseasonably warm, many have been asking about the accuracy of the models. I don’t know for sure, but I’ll take a guess and say that I think they are going to be off this year in many places.

Growing degree days are a simple way to estimate the progression of the season, similar to but much easier than tracking soil temperatures. Growing degree days don’t start accumulating until the average temperatures get above freezing (sometimes above 50F). Normally this coincides with when the snow and frost leave. However, due to the quick onset of really warm temperatures, many places may still have had frost in the ground when the growing degree days were skyrocketing. In these situations, the models will be ahead of reality, in situations where the frost was out before the warm streak, the models may be pretty accurate. Either way, I recommend erring on the upper end of the target ranges this year. Also, for the Primo/Proxy users, I recommend going with split applications this year. Check out the USGA research article on our Primo/Proxy GDD page by Randy Kane and Lee Miller for application ideas.

One way to check how the models correlate to soil temperatures is to measure soil moisture and pay attention to the crabgrass pre-emergent GDD model. The optimum timing for applying crabgrass pre-emergent herbicide is when soil temperatures are 50-55 F. The optimum growing degree days for pre-emergent application is 250-500 GDD. So if soil temperatures (two inch) are 50-55 degrees F when the model is between 250 and 500 GDD, I’d say things are on track. However if soil temperatures are still delayed significantly when we hit 350 GDD, then you can bet that the GDD models for the rest of the year will be off.

Doug Soldat
608-469-0378

The 2011 Wisconsin Turfgrass Research Reports are now available. The 2011 reports contain valuable information on turf cultivars, herbicide efficacy trials, fungicide evaluations, fertilizer and soil fertility trials, and more. Download a copy here.

Welcome to the new UW Turfgrass website. We’ve made several major changes that we hope you’ll find useful.

First, we’ve added many growing degree day models used by the Michigan State GDD Tracker. Use the maps to improve seed head suppression, pest control, and efficacy of growth regulation.

Next, we’ve added University of Wisconsin radar, which is fast and accurate so you can see what’s headed your way.

The irrigation scheduling shows yesterday’s ET, a link to get ET from your site delivered daily to your email, and an awesome spreadsheet that can take the guesswork out of irrigation scheduling.

Use the calendar function to see what’s going on in the world of turfgrass science and education.

We want this site to be as useful as possible to you so please share your comments and suggestions about the new site with me.

Thanks,
Doug Soldat
djsoldat@wisc.edu