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Winter Weather Update and Topdressing Trial

January 10, 2012
Golfers are taking advantage of the uncharacteristically warm weather with a rare January round.

Temperatures dropped into the low 40’s over the weekend as a cold front moved across the state. Considering the weather we have experienced lately however, the “cooler” temperatures haven’t felt so bad. Many parts of the state broke records last week as daytime temperatures surged into the 50’s and 60’s. Temperatures during the month of January have been just over 10 degrees higher than normal. Golfers took advantage of the mild weather last week and dusted off their clubs for a rare January outing.

Overall, temperatures have been above average since last October and this has prevented the ground from completely freezing in many parts of the state. Precipitation totals were above average for the month of December thanks in part to 3 rain events. It appears that nearly all of the precipitation that occurred in December was able to soak into the ground. This was a very welcome development over northwestern Iowa where severe drought conditions are still present.

The threat of turf damage from dessication is certainly elevated with the open winter we have experienced thus far. Dr. Christians provided a nice historical perspective of turf dessication in his posts last week along with the benefits of late fall sand topdressing. We also took the opportunity to put out a couple sand topdressing trials last week to address this issue.

We applied sand topdressing to creeping bentgrass putting green turf exposed to northwest winds that had not received any topdressing for winter protection. Sand was applied at 1/16, 1/8, 1/4, and 1/2 inches. An untreated control was also included in the trial which received no sand topdressing.

Results from this trial should tell us if there are any benefits from mid-winter sand topdressing during “open” winters and how thick of a topdressing layer needs to be applied. Special thanks to Brian Abels, Golf Course Superintendent, Jewell Country Club, and James Legg, Golf Course Superintendent, Briarwood Club of Ankeny for letting us use their facilities for this work.

Pictures of the sand topdressing trial can be seen below. We will be evaluating the effects of this trial in the spring and will post results as they become available.

A wood frame with three layers of chicken wire was positioned over each plot.  The wire helps evenly distribute the topdressing sand across the plot.


Four thicknesses of sand topdressing are being evaluated in this trial for their effect on protection from winter dessication.  An untreated control was also included.





Overall view of winter topdressing trial.  Special thanks to Brian Abels, Golf Course Superintendent, Jewell Country Club, and James Legg, Golf Course Superintendent, Briarwood Club of Ankeny for letting us use their facilities for this work.

Marcus Jones
Assistant Scientist
Iowa State University





Time for Primo/Proxy Applications

March 21, 2012
Forsythia bush in full bloom.  Picture taken March 19, 2012.

The winter season officially ended on Monday. With the mild weather we experienced this offseason, at times it seemed like winter never arrived. Central Iowa saw temperatures climb into the 80’s for five consecutive days last week. According to the National Weather Service, it’s the first time that’s ever happened during the month of March. Four inch soil temperatures are creeping into the low 60’s across most of the state. Forsythia bushes are in full bloom.

So what does this bizarre weather mean to you and your turf? The weather is well ahead of normal and agronomic practices will need to occur sooner than normal as a result. Avoid the temptation to schedule activities solely base on the calendar because this spring has been anything but normal.

Growing degree days (GDD) can help give you an idea of how unusual this spring is shaping up to be. GDD’s are a measure of heat accumulation and are used to predict plant and pest development rates. Daily maximum and minimum temperatures are used along with a base temperature to calculate a GDD value for each day. Below are two maps showing accumulated GDD’s from March 1 through March 20 for 2011 and 2012. As far as GDD’s go, most parts of the state have accumulated 2 to 3 times the number of GDD’s as this same time last year. In fact, it took until April 10 last season to accumulate the number of GDD’s we have experienced so far.

Growing degree day comparison from March 1 to March 20 for 2011 and 2012. 

Michigan State University has conducted research looking at GDD’s for a number of turf applications including Primo/Proxy applications. Their research indicates that the ideal GDD ranges for Primo/Proxy application is 200-500. Our accumulated GDD's indicate that the entire state is within the target range for Primo/Proxy. Now is the time to make your Primo/Proxy application for seedhead suppression of annual bluegrass.

Marcus Jones
Assistant Scientist
Iowa State University