April 17, 2015

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Spring Preemergent Applications for Crabgrass

Every year around this time I start receiving questions regarding when to apply preemergent herbicides for preventing crabgrass establishment in lawns.  Crabgrass germination is driven by soil temperatures and because of this we cannot rely on a calendar date to tell us when to apply our preemergent products.  The reality is, if we wait too long and miss the window of opportunity to apply crabgrass preventers, these products will not do much for control of crabgrass.  For this reason I like to rely on a couple of website resources that help to determine when to make these applications.  The first website that I like to use can be found here: http://www.gddtracker.net/  This is a site operated by Michigan State University and the model uses air temperature predictors to determine when to apply crabgrass preventers.  Simply select the tab “Crabgrass PRE”, enter your zip code, and the map will be created.  Below is the current map for Minnesota.  As you can see, we are just getting into the time for optimum prevention of crabgrass with preemergent herbicides.  Based on the extended forecast calling for sub-50 degree air temperatures, we still have plenty of time to get these products down. For a more detailed explanation of how to utilize this website for crabgrass prevention, see this great post from Dr. Aaron Patton at Purdue University: http://purdueturftips.blogspot.com/2013/04/when-should-i-apply-my-preemergence.html 



The other website that I like to use is the University of Minnesota’s Climatology Working Group Site: http://climate.umn.edu/  [Read more…]

Lawn Care Tips For Our Early Spring Warmup (WCCO)


Regional Golf Course Report (Spring 2015)

By Matt Cavanaugh, Sam Bauer, and Dr. Brian Horgan

How quickly things can change.  Shorts and sandals are now the new theme on campus this week, which is engaging considering we experienced overnight lows below zero just last Friday.  It is always interesting to discuss the weather in Minnesota.  Snow fall last winter totaled around 70 inches of with the average being 54 inches.  As of March 6th, MSP airport has only had 27 inches of snow compared to 40 inches seen in Lexington, Kentucky this season.  It would we a crazy spring if we are to hit the averages.  According to the U.S. Drought Monitor, most of Minnesota is considered to be abnormally dry with a few counties considered to be in a moderate drought (Cass, Hubbard, Wadena, Norman, Clay, Wilkin).  Eastern North Dakota is seeing the same, but most of Wisconsin has seen adequate moisture this winter.  With all that being said, we are heading into a week that forecast highs in the 50’s and low 60’s which will initiate the plants deacclimation process, the breaking from dormancy.  Much like the shorts and sandals would suggest.

In the updates below from Superintendents around Minnesota, Eastern North Dakota and Western Wisconsin, you will notice a theme of early snow, a December and January thaw and then cold temperatures with little snow cover through February which has prompted thoughts of desiccation issues.

The general timeline looks like this for most of the region:

  • First significant snow: November 10-12.
  • Prolonged high temperatures:
    • December 11-16th with temperatures ranging from 32 to 50 during this period.
    • December 21-27th with temperatures ranging from 32 to 40 during this period.
    • January 23-29th with temperatures ranging from 32 to 44 during this period.
    • February 2015 was the 14th coldest on record statewide.

Metro Area: Roseville and Edina

Mike Manthey at Midland Hills Country Club has reported minimal snow cover of about 1-2 inches at the end of February and some ice on low spots in his fairways, but this is only a few weeks old and nothing clear or very solid.  Due to the lack of snow cover, Mike does anticipate some desiccation on higher/exposed fairways and surrounds, but little ice damage at this point.  During the two warm ups in December and January, Mike and his crew did remove water that had collected on top of the greens where he uses GreenJackets.   The other greens are covered with Excelsiors and the extended days of warmth allowed for all the water to move off or through the greens where Excelsiors are used.  Mike has been using some antidessicant products, and will consider adding more fairways and surrounds into the program next year depending on the damage seen this spring.

Brandon Schindele at Edina Country Club has also reported only about 1 inch of snow on most of the course at the end of February, but does not have any ice on the playing surfaces.  Moisture from the December and January thaws either drained off or infiltrated into the soil.  Brandon does not use any kind of cover on his greens.  Temperature sensors in greens (at 3 inches) in December were showing readings as high as 36, but have generally been in the mid to low 20’s with a low around 10.  [Read more…]

Pesticide Applicator Exam Preparation Workshop


Winter Desiccation of Turfgrass

By Maggie Reiter, Graduate Research Assistant

Major causes of turfgrass winterkill are crown hydration, direct low temperature kill, anoxic conditions under ice sheets, diseases like snow mold, and winter desiccation. These factors often work together to cause turf loss, and damage can be variable across the landscape of a golf course, sports field, or home lawn. During Minnesota winters, we don’t worry much about desiccation because we have consistent snow cover that protects the turf. This year, however, snow cover is scarce and most of Minnesota has snow accumulation below average. In some parts of Minnesota, the snowfall departure is around 20 inches below historical means (Midwest Regional Climate Center).snowfall departure from mean Feb 6 2015

Desiccation is extreme dryness that occurs when water in the plant is lost at a faster rate than water is replaced. This is a form of abiotic stress that can happen any time of the year. Symptoms of desiccation involve tissue damage that appears as browning and thinning of the turf canopy. Desiccation to the leaves can be tolerated, and usually water dehydration is not severe enough to affect the crown of the plant. But, newly-seeded or succulent plants are more susceptible to harm and death could occur. Desiccation is most harsh on elevated areas that are exposed to dry winds (Beard, 1973). Winter desiccation can injure semi-dormant turfs in frozen soil, where the plants are not able to uptake water as fast as they lose water. In Minnesota, these conditions may happen in the late winter or early spring, especially with our recent lack of snow cover.


An anti-desiccation study at the University of Minnesota Turfgrass Research, Outreach, and Education Center

There is not a great deal of research on winter desiccation injury and management. In a field setting, winter damage is often a dynamic combination of factors and the impact of each effect is difficult to discern. In a greenhouse or laboratory, desiccating conditions can be challenging to reproduce. There is a decent volume of research on turfgrass drought, but the results cannot be translated to desiccation because drought tolerance is not the same as desiccation tolerance. Drought tolerant plants are able to maintain moisture inside cells when water availability is scarce. Desiccation tolerant plants are able to survive reduced water content in cells and recuperate when water becomes available (Alpert, 2005).

A general rule of thumb is to be wary of desiccation when air temperatures are more than 20 degrees F above soil temperatures. Control measures for winter desiccation include installing wind breaks or snow fences in areas with perennial problems. Golf courses and sports fields can use protective covers and heavy sand topdressing for high-value turf. Anti-desiccant products exist for turf, ornamentals, and trees. These treatments coat plants with a sealant to prevent water loss through the leaves.

Heat waves are projected to increase in frequency and magnitude while changes in precipitation will be variable (IPCC, 2014). This climate will continue to reduce snow cover in the North Central and could foster desiccating conditions for turfgrass. Although winter desiccation is not heavily reported in Minnesota at this time, it is something to be watchful of in the future.

Literature cited

Alpert, P. 2005. The Limits and Frontiers of Desiccation-Tolerant Life. Integrative and Comparative Biology 45:685-695.

Beard, J.B. 1973. Turfgrass: Science and Culture. Prentice-Hall, Englewood Cliffs, NJ.

IPCC. 2007. Climate Change 2007: Summary for Policymakers. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, and New York, NY.

Midwest Regional Climate Center. 2014. Regional Maps: Snowfall Season-to-Date and Annual Snowfall Normals. Illinois State Water Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign.

2014 Cultivar Evaluation Results

The 2014 Cultivar Evaluation Results are now available and published online.  To view these results, click the “Cultivar Evaluation Results” tab under the Research section on the left of this webpage.  Clicking this link will initially bring you to the 2014 data page, but you can view archived data from 2007-2013 as well.  Study labels are preceded by the date in which that study was planted.  For example, “2011 NTEP Kentucky bluegrass” was established in 2011, but you will be viewing the most recent data if you are in the 2014 tab.

How to use the results:

Some trials may have 100 or more entries.  Generally, named cultivars (ex: ‘Beacon’ hard fescue) will be commercially available through big box stores, garden centers, seed distributors, or professional suppliers.  Numbered entries are experimental and not available for purchase (ex: ASR172 slender creeping red fescue).  The main rating of concern when looking to purchase a particular cultivar will be turfgrass quality, which is a 1 to 9 scale rating where 1 = worst turf quality or dead turf, 6 = minimum quality acceptable, and 9 = best possible quality.  The LSD (least significant difference) at the bottom of each table is a statistical value that can be useful for determining if one cultivar is different from another.  A LSD value of 0.7 would mean that statistically a rating of 6.6 is not different than 6.0, but a rating of 5.9 would be.

Salt-Tolerant Roadside Grasses: Does Anything Actually Survive?

By Matt Cavanaugh, Research Scientist

The seven county metro area uses nearly 350,000 tons of road salt each year with uses coming from the Minnesota Department of Transportation (81,000 tons), counties (70,000 tons), cities (115,000 tons), and private entities (84,000 tons) (Sander et al. 2007).  The salt that is being used on Minnesota roadsides is often too high causing death for many of the grasses established in these areas.  Why do we even attempt to grow grass on roadsides?  Benefits of having roadside grasses are improved water quality, erosion reduction, trapping containments coming from the road, provide animal habitat, reduce road noise and provide an aesthetic value to the landscape.  To date there have been significant steps taken to improve grass survivability on Minnesota roadsides.  Initial work at the University of Minnesota has revolved around finding a better grass species mix that is more tolerant to salt applications used in Minnesota during the winter (Friell et al., 2012; Friell et al. 2013).  This work has resulted in a salt-tolerant sod quality assurance program that provides salt-tolerant sod for use on roadsides in Minnesota.  Before going on I would like to define “salt-tolerance”.  Tolerance means that a plant can take certain amounts of salt before it will eventually die from over application.  Tolerance should not be confused with resistant which would imply that the grass would not be impacted by the application of salt.

Making of Salt-Tolerant Grasses

Image 1

Picture 1: Deterioration of Kentucky bluegrass sod due to heavy salt loading

The original salt-tolerant sod mixture included 15-20% alkaligrass, 15-20% red fescue, 10-15% Park Kentucky bluegrass, 20-30% improved Kentucky bluegrass, and 20-30% low-maintenance Kentucky bluegrass.  The majority of this mixture ends up being Kentucky bluegrass which is generally a very good performing grass for Minnesota, but it is not very salt tolerant on Minnesota roadsides (picture 1).

Alkaligrass represents as much as 20% of the mix and, as the name implies, is a very salt-tolerant grass. However, research at the University of Minnesota has demonstrated that alkaligrass is not very persistent in the low-maintenance environment of Minnesota roadsides.  So, as much as 85% of the original salt-tolerant mix does not perform very well, long term, on Minnesota roadsides.  What does perform well then?  What species will provide the best salt-tolerance and long term survivability?

A total of 9 different turfgrass species representing 75 turfgrass cultivars were evaluated for salt-tolerance on Minnesota roadsides (picture 2).  This evaluation resulted in the recommendation of a new salt-tolerant roadside grass species mixture to be used in Minnesota.  Most of the top performing salt-tolerant
species ended up being fine fescues.  The term fine fescue represents 5 turfgrass species that all have very similar traits including shade tolerance, drought tolerance and low fertility requirement.  Fine fescues include slender creeping red fescue, strong creeping red fescue, sheep fescue, Chewings fescue and hard fescue.  From the five species of fine fescues, research has shown that slender and strong creeping red fescue are best in salt loading situations and in areas receiving reduced fertility, thus making them a perfect choice for a salt-tolerant roadside mixture in Minnesota (Friell et al., 2012).


Picture 2: 75 cultivars representing 9 different species planted in 3 replications on a MN roadside

With the work conducted at the University of Minnesota, it was recommended to change the salt-tolerant roadside mixture to contain 40% total of a combination of hard, Chewings, and sheep fescue (several cultivar options), 20% slender creeping red fescue (3 cultivar choices), 20% strong creeping red fescue (5 cultivar choices) and 20% Kentucky bluegrass (4 cultivar choices).  From the
original salt-tolerant grass mixture, alkaligrass has been removed due to the lack of long term persistence in a low-input situation and the amount of Kentucky bluegrass has been greatly reduced from the original salt-tolerant mixture.  Kentucky bluegrass is currently still being used to provide added strength when these mixtures are being harvested for sod.  Historically, fine fescues are not used in sod production due to their perceived lack of  sod forming ability.  Research at the University of Minnesota has demonstrated that Kentucky bluegrass does not necessarily create a stronger sod and that mixtures containing fine fescue can provide acceptable sod strength which was not previously thought.  Roadsides represent the largest area of maintained turfgrass that we have in our landscape and provides great benefit to the landscape.  Developing species mixtures that are more tolerant to the pressures Minnesota winters provides will greatly enhance the roadside landscape in Minnesota.  Currently there are 6 sod farms producing salt-tolerant sod that is already on Minnesota roadsides including the boulevard in front of the Governors’ Mansion (picture 3).


  1. Friell, J., E. Watkins, and B. Horgan. 2012. Salt tolerance of 75 cool-season turfgrasses for roadsides. Acta Agriculturae Scandinavica, Section B – Soil & Plant Science 62:44-52.
  2. Friell, J., E. Watkins, and B. Horgan. 2013. Salt-tolerance of 74 turfgrass cultivars in nutrient solution culture. Crop Science 2013 53:1743-1749.
  3. Sander, A., E. Novotny, E. Mohseni, and H. Stefan. 2007. Inventory of Road Salt Use in the Minneapolis/St. Paul Metropolitan Area. Project Report No. 503. University of Minnesota, St. Anthony Falls Laboratory. Prepared for the Minnesota Department of Transportation and the Local Road Research Board.
Pic 3 Gov

Picture 3: MNST-12 salt tolerant fine fescue sod planted at the MN Governor’s Residence in St. Paul


Educational Opportunity: BEE AWARE- The Importance of Pollinators in the Landscape

MTGF Super Tuesday Set for January 13, 2015
Cost is $65. Education points are available. 
bee aware

Educational Opportunity: The 2015 Great Lakes School of Turfgrass Science Online (For Professionals) January 7th – March 25th, 2015

Any investment in quality continuing education opportunities benefits employees and employers alike. The 2015 Great Lakes School of Turfgrass Science Online is designed to help meet the continuing education needs of any individual or organization.  This 12-week program will have training sessions accessible live online on Wednesday evenings from 6 to 8pm (Central Standard Time) or the option to view the recorded sessions. This 12-week certificate-based program aims to provide participants with thorough and practical continuing education in turfgrass management.  The course is directed by educators from the University of Minnesota-Twin Cites and the University of Wisconsin-Madison, with 12 turfgrass scientists and educators from eight Land-Grant Universities.

Turfgrasses are a resource in our urban community environments and best management practices are aligned with environmental, economic & societal priorities. The Great Lakes School of Turfgrass Science provides participants with the science based principles needed to effectively manage turf for recreation, sport, aesthetics and environmental protection. The Great Lakes School of Turfgrass Science is a quality training opportunity for:

  • Practitioners that establish and maintain turfgrass for athletic fields, consumer/commercial lawns, golf courses, recreation/parks, and sod production
  • Technical representatives from industry (suppliers of equipment, plant protectants, fertilizer, etc.)
  • Those new to the industry – wanting to get trained and off to a great start
  • Those with experience in the industry – to review/update their knowledge and practices

The registration deadline is December 31st, 2014. Students will have access to the course and materials at their convenience during the 12-week period via moodle class management system.  The fee for the course is $495, which includes supplemental materials and a certificate after successful completion of the program.  Visit this link to register: http://z.umn.edu/2015greatlakesturfschool

Early registration is encouraged and pre-registration is required.

For Further Information: Contact Sam Bauer, Assistant Extension Professor – University of Minnesota, Email: sjbauer@umn.edu Phone: 763-767-3518.


Turf and Bees: What’s the buzz on pesticides in lawns?


White clover and dandelion provide great early season forage for pollinators in lawns

By Ian Lane, Graduate Research Assistant

If you have been paying attention to the news lately, you know that bees have been making headlines. News outlets have done an amazing job of helping scientists sound the alarm on unsettling declines in bee pollinators. While we have good evidence for declines in honey bees and some of their cousins, the bumble bees, the cause of this decline is hard to pinpoint. Current thinking in the scientific community puts the decline down to a number of interacting factors, including reduction in stable food sources, introduction of bee diseases, and the irresponsible use of insecticides. While it’s difficult to tease apart how these factors interact, we do have some good knowledge about how lawns fit into this theoretical framework.


Lawns are home to a number of weeds that are the bane of homeowners. While our gut reaction may be to reach for a herbicide, it’s worth noting that many weeds actually can provide high quality forage for bees. Two of the most important lawn forage plants are the common dandelion (Taraxacum officinale) and Dutch white clover (Trifolium repens). Dandelions are one of the earliest, and often only, blooming flowers of spring. This early source of pollen and nectar is essential to overwintering honey bee colonies as they begin the process of raising new workers. White clover is another spring bloomer (though not as early) that provides highly nutritious pollen throughout the year. While the exact nature of bee’s relationship with these flowers isn’t widely studied, recent research at the University of Kentucky sought to characterize the types of bees visiting dandelions and clover. They found  surprising diversity on white clover, including a number of at risk bumble bees (Larson et al. 2014). Similar preliminary research here at the University of Minnesota confirms many of their findings.

There may also be some solutions for homeowners looking to control weeds but leave clover in their lawn. One common herbicide known as 2,4-D is effective on many broadleaf weeds, but generally ineffective on clover. Small demonstration trials at the University of Minnesota confirm that 2,4-D has relatively low action on clover but is relatively effective against other weeds.


The another type of pesticide that can make a big impact on bees are insecticides . Much of the recent attention on pollinators has focused on a class of insecticides known as the neonicitinoids. Neonicitinoids are used in turf to help control a number of insect pests, most importantly grubs. They work by “dissolving” into the irrigation water or rain, which is then taken up by the plant and becomes part of the leaf and root tissue. This ensures that any insect munching on the tissues of your grass gets a lethal dose, and your lawn stays green. While bees would never have a reason to take a bite of your grass, your helpful lawn weeds are a different story. It turns out that not only do these insecticides move into plant leaves and roots, but the nectar and pollen of the flowering weeds as well.

Many studies have looked to see if neonicitinoids applied to lawns full of clover have negative effects on bumblebee colonies. The researchers in Kentucky  do this by getting a colony of the commercially available common eastern bumble bee (Bombus impatiens), placing it on a patch of flowering clover that is treated with a neonicitinoid, then caging them so they are forced to forage on the treated clover. These experiments are always accompanied with a similar set-up but on a non-treated patch as a point of comparison. Here again the University of Kentucky has been leading the way with a study published in 2002 (Gels et al. 2002) that found if imidacloprid (a type of neonicitinoid) was applied to flowering turf without any post application irrigation that bumble bee colonies suffered worker weight loss, increased worker death, and sluggish behavior. However, if irrigation was applied directly following these imidacloprid applications, no negative responses were seen.

Similar responses were seen in a study investigating clothianidin, another type of neonicitinoid (Larson et al. 2013). Bumble bee colonies that were confined over patches of flowering clover, and that had the high label rates of clothianidin applied to the turf, saw dramatic effects on the number of workers, new queens, as well as total colony weight when compared to control colonies. The effects of irrigation were not part of this study, but when clover nectar from nearby sights that had been applied with clothianidin were sampled, they found high amounts of the neonicitinoid. This study’s main aim was to compare clothianidin to a new chemistry of insecticides called anthranilic diamide (specifically chlorantraniliprole). This new class of chemical had seemingly no adverse effects on bumble bee colonies when compared to the controls. While there is more research to be done, this is a promising alternative to neonicitinoids for insect control in turf.  You can currently purchase chlorantraniliprole for use on residential and commercial turf, and trade names include “Scott’s Grubex” or Syngenta’s “Acelepryn”. 

While urban landscapes and lawns are only one part of a very large system, they are nevertheless an important part of a vast majority of people’s lives. Promoting animal diversity in urban landscapes, be it pollinator or other, helps improve important issues related to stormwater runoff (rain gardens and buffer strips) and urban agriculture (pollination and biocontrol services) and also enriches everyday life through learning opportunities and aesthetic value. Even the smallest effort, such as leaving some weedy flowers or choosing a safer insecticide, may make a difference.

Stay Informed

A new series on pollinators is being offered by the University of Minnesota Landscape Arboretum.  “Pollinators: What you need to know and how to make a difference” is a 3-part series focusing on: 1) Plants and People, 2) Pesticides and Other Problems, and 3) Policies and Politics.

The Minnesota Turf and Grounds Foundation will be offering a 1-day session on Super Tuesday of the Northern Green Expo, January 13th, 2015.  “Bee Aware: The importance of pollinators in the landscape” will feature expert presenters discussing real world issues surrounding pollinators, as well as practical strategies to promote them in the landscape.  Stay tuned to www.mtgf.org as this program develops.   

Works Referenced

Gels, J. A., D. W. Held, and D. A. Potter. 2002. Hazards of Insecticides to the Bumble Bees Bombus impatiens (Hymenoptera : Apidae ) Foraging on Flowering White Clover in Turf. J. Econ. Entomol. 95: 722–728.

Larson, J. L., A. J. Kesheimer, and D. A. Potter. 2014. Pollinator assemblages on dandelions and white clover in urban and suburban lawns. J. Insect Conserv. 18: 863-873

Larson, J. L., C. T. Redmond, and D. A. Potter. 2013. Assessing insecticide hazard to bumble bees foraging on flowering weeds in treated lawns. PLoS One. 8: e66375.