October 31, 2014

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

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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.

Herbicides

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.

Insecticides

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.

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.

GLTS

Have you tested your soil lately?

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Drought Trials on the St. Paul Campus

By Maggie Reiter, Graduate Research Assistant

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Rainout shelter on the St. Paul campus. Photo: Maggie Reiter

Our worldwide water resources are declining at an alarming rate, both in quantity and quality.  Because of this, legislation has been enacted to restrict our water use and the cost of water is increasing.  In addition, global climate change assessments predict that our drought events will continue to increase in both frequency and magnitude.  We must manage our turfgrass in a way that maintains performance and playability in order to cope with these trends of reduced water availability.

We have several field trials in Saint Paul evaluating turfgrass species and cultivars under acute drought.  The trials are located under a rainout shelter (image 1).  The rainout shelter is a state-of-the-art device that allows us to withhold precipitation and impose an experimentally controlled drought on the research area.  Our shelter is an automated structure that will move to cover the test area during a rainfall event and remains off the area during fair weather.  The entire apparatus can be moved with a signal from a control box onsite, a cellular text message, or a rain sensor located on top of the shelter.

Data is collected before, during, and after the 60-day drought period.  Before the drought begins, the entire area is irrigated to uniformly wet the soil.  For the next 60 days, the turf plots receive no water from irrigation or precipitation. After the drought, the area is irrigated with 1 inch of water per week and recovery data is collected for 45 days.  Data collected through the entire experiment includes visual ratings of turfgrass quality, digital images for color analysis, and chlorophyll index readings to quantify plant tissue health.  All plots are mowed at 2.75 inches.

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Fine fescues are able to maintain color and quality through drought because of a low water requirement. Photo: Maggie Reiter

Turf species have different responses to drought. Tall fescue is drought avoidant and can withstand the drought conditions well due to a deep root system. Fine fescues maintain adequate quality through the drought conditions because of an overall lower water requirement. The fine fescues have a small leaf area and slower growth rate, so the plant needs less water than other species. Kentucky bluegrass has a moderate drought tolerance. This grass turns brown and dormant but will recover with irrigation. Perennial ryegrass has a poor drought tolerance and usually dies under a 60-day drought period. Furthermore, there is some variation among cultivars within a turfgrass species.

Future research with our rainout shelter includes evaluating different management practices to withstand drought, looking at drought tolerance of other species and varieties, and assessing drought performance of shorter-cut turfgrass.  Once we can identify the best grasses and management practices to endure acute drought, we can employ these systems to reduce our water use and foster a durable turfgrass stand.

 

Low Input Versus Traditional Turfgrass: Comparing Runoff Quantity and Quality

Pamela Rice, Research Chemist and Adjunct Professor, USDA-Agricultural Research Service and Department of Soil, Water and Climate

Brian Horgan, Professor, Department of Horticultural Sciences

Strategies used to maintain managed biological systems, including golf course turf, often involve application of fertilizer and pesticides to optimize plant health and protection.  The transport of applied fertilizers and pesticides with runoff to surrounding surface waters has been shown to result in enhanced algal blooms, promotion of eutrophication or negative impacts on sensitive aquatic organisms or ecosystems.  In previous research we demonstrated that changes in cultivation practices (e.g. type and timing of core cultivation) reduced the volume of runoff and the percentage of applied pesticides and nutrients that moved off-site with runoff from creeping bentgrass turf.  In the current study we evaluate the influence of turfgrass species on runoff quantity and quality. 

Experiments are underway to compare the volume of runoff and measure the amount of pesticides and nutrients in runoff from conventional versus low input turfgrasses.  Plots (20ft x 80ft) maintained as a golf course fairway (0.5 inch height of cut) were seeded with bentgrass (Dominant Xtreme 7: a 7:3 mixture of ‘007’ creeping bentgrass and ‘SR 1150’ creeping bentgrass) or a fine fescue mixture (equal parts ‘Chariot’ hard fescue, ‘Seabreeze GT’ slender creeping red fescue and ‘Cardinal’ strong creeping red fescue and ‘Longfellow II’ chewing fescue).  Each plot is equipped with runoff gutters, a flume, an automated sampler, and a flow meter to measure flow rates, calculate runoff volumes and collect subsamples of the snowmelt and rainfall runoff.  Studies will be performed with fertilizer and pesticides applied at label rates to both the traditional and low input turf, as well as additional studies with pesticides applied at label rate for bentgrass turf and 2/3 label rate for the low input fine fescue turf.

To date we have observed the fine fescue mixture produces greater quantities of snowmelt and rainfall runoff than bentgrass (Figure 1).  Collected runoff samples have been processed and are being stored frozen until completion of chemical analysis.  In our previous studies with creeping bentgrass turf we found that runoff volume was more influential than chemical concentration to the overall mass of chemicals transported off-site with runoff.  We are curious to learn if this trend continues with the low input fine fescue mixture or if other influencing factors are of greater importance.  Data collected from this study will guide strategies to manage low input fine fescue mixtures in order to provide optimal results for golf course managers, golfers and the environment. 

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Figure 1.  Comparing runoff from bentgrass and fine fescue turf.  Examples of hydrographs collected in June 2014.

 

 

Educational Opportunity: Beyond Rain Gardens (UMN Landscape Arboretum)

Beyond Rain Gardens

The Potential of Turfgrass to Sequester Carbon and Offset Greenhouse Gas Emissions

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Photo: Julie Weisenhorn

By Madeline Leslie, Graduate Research Assistant

Climate change is a serious environmental issue that will continue to cause widespread concern around the globe. As the amount of carbon dioxide, nitrous oxide, and methane increase in our atmosphere, the ongoing effects of higher temperatures will become more apparent. We have already seen certain trends occurring that scientists have attributed to climate change, such as more frequent droughts, higher sea levels, melting glaciers, and shifting plant and animal ranges (IPCC, 2007). Society can help to help mitigate the effects of climate change in two ways. One is the reduction of greenhouse gas emissions, and the other is the sequestration of carbon dioxide within natural or artificial reserves.

Turfgrass is often seen as a high input landscape feature and as such has acquired a bad reputation because of the negative consequences associated with high input management. Fertilizer and pesticides applied in excess can run off turf areas and contaminate local waterways. Additionally, lawn mowers, aerators, and other turf maintenance equipment release greenhouse gasses into the atmosphere. Despite these negative impacts, turfgrass actually has the potential to offset emissions by sequestering carbon dioxide. Through the process of photosynthesis, all plants remove carbon dioxide from the air and utilize it to form new growth, including root mass. As turfgrass roots die, they decompose into soil organic matter, fixing carbon in the soil. In this way, turf areas can sometimes be carbon sink for greenhouse gases rather than a source.

Recently, some significant research has been conducted that has shown encouraging results regarding the ability of turfgrass to sequester carbon. One such study used a model to examine the potential for carbon sequestration on home lawns, and found that lawns are able to sequester anywhere from 25.4 to 204.3 g C/m2/year (Zirkle et al., 2011). Though this is only a small fraction of the amount emitted by the United States each year (EPA, 2013), if all or most turf areas were able to sequester this amount, a significant difference could be made in the net carbon emission of the United States. Kong, et. al. (2014) found that athletic fields, parks, and university campus lawns also had the ability to sequester more carbon than they emitted. However, this study also pointed out that there are limitations to how much carbon soil can hold, and as such turf areas can only sequester carbon for a certain amount of time. Finally, a study conducted on home lawns around the U.S. also found that these areas could sequester more carbon than they released, but on average became net carbon sources after 184 years, as the soil ceased to be able to hold additional carbon, but maintenance activities continued (Selhorst and Lal, 2012).

These studies show that turfgrass areas do indeed have the potential to sequester more carbon than they emit, therefore at least not contributing to the problem of global warming. However, after a certain amount of time turfgrass becomes a net source of greenhouse gasses when the soil reaches its carbon storage capacity. The length of this time period depends on many factors, such as soil type and climate, but especially on maintenance practices.  More research is needed on what environmental conditions result in the maximum amount of soil carbon storage, but individuals can take immediate action on their own by choosing to plant a low-input turfgrass species, which will reduce emissions from maintenance. This will increase the likelihood that your turf area will be a net sink for carbon for a longer period of time; while this by itself will not solve the problem of global warming, it at least can help reduce it.

References

EIA. 2013. What are greenhouse gases and how much are emitted by the United States?. EIA: Energy in Brief.

IPCC. 2007. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 2007. IPCC.

Parry, M.L., O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson (eds) Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Selhorst, A., and R. Lal. 2012. Net Carbon Sequestration Potential and Emissions in Home Lawn Turfgrasses of the United States. Environ. Manage. 51(1): 198–208.

Zirkle, G., R. Lal, and B. Augustin. 2011. Modeling carbon sequestration in home lawns. HortScience 46(5): 808–814.

 

UMN and MTGF Field Day Back on the St. Paul Campus

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Repairing Lawns Following Flooding

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Water slowly receding from turf that will have marginal recovery. Photo: Sam Bauer

The month of June was a wet one.  Many homeowners, grounds managers, and golf course superintendents are finally starting to see some of the flood waters recede, although standing water is still covering many of our landscapes.  The University of Minnesota’s Climatology Working Group is calling June of 2014 the wettest month on record.  In the Twin Cities we saw 11.36 inches of rain for the month, almost 7 inches above average and falling just short of the 11.67 inch record set in 1874 (www.climate.umn.edu).  

We are starting to see a wide range of damage to lawns and turfgrass throughout the state.  In situations where standing water was present for greater than 7-10 days, the turf is almost certainly dead and will need to be repaired.  Turfgrass covered for less time has a greater chance of recovery, but every situation is different.  Unfortunately, there is not good information regarding how long turfgrass can survive under standing water because there are so many potential mechanisms of damage.  These mechanisms can be separated into 2 groups: primary damage from waterlogging and secondary damage after the water has gone.

Primary damage includes such factors as water temperature and water depth.  Water temperature will probably be the most important factor determining survival, with turfgrass death occurring in only a few days when water temperatures are 80 degrees F and higher (note: we did not see water temperatures this high during recent floods, unless it was very shallow and stagnant).  When water temperatures are lower the turf can still die, with lack of oxygen being the primary culprit.  If the turf is completely submerged, this will be a worse case than if some of the leaves and crowns are exposed.

Secondary damage might be associated with sediment buildup, fungal diseases, moss and algae, and weed infestation.  While we have very little control over the primary mechanisms causing damage, now is the time to start thinking about how to reduce damage that could be caused by the secondary mechanisms.  The primary disease you could expect to occur after flooding is pythium blight.  Look for circular or irregular patterns of dead turf inside of healthy turf areas.  For more information on pythium blight, follow this link to a fact sheet from Purdue University Extension: Pythium Blight.   Remember that plant disease samples can be submitted to the University of Minnesota Plant Disease Clinic for correct identification and control recommendations.  If you have confirmed that you lawn is infected with pythium or other diseases, I recommend contacting a lawn care contractor to carry out the control measures.    

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This turf was covered with water for 8 days and will not recover. Photo: Sam Bauer

To this point I’ve been recommending that homeowners be patient and assess the damage as it presents itself.  Turf that appears to be dead following the receding of flood waters should be monitored for several days; if no green tissue appears within 7-10 days, you can assume it is dead and should start forming a renovation plan.  In many cases, you might be surprised with the amount of turf that recovers when the conditions are right.  In situations where sediment or debris buildup has occurred, you will want to act fast to remove it.  The previous Turfgrass Extension Educator, Bob Mugaas, wrote a great article addressing repair of areas where sediment has built up in the 2010 edition of the Yard and Garden News.  That article can be found here: Repairing Flooded Lawns 

Timing of repair can be difficult.  The cool-season grasses that we grow in Minnesota do not establish well in the middle of the summer due to the high heat and diseases that may occur.  If at all possible, I recommend waiting to seed until temperatures cool in the early fall around mid- to late-August.  Fall seeded lawns will have a much better chance of a successful establishment.  With that being said, recovery in the short term could be promoted by aerating your soil once it is dry and/or applying light rates of nitrogen based fertilizer.    

Choice of turfgrass seed can be very important.  If flooding is a common occurrence on your lawn, I would recommend Kentucky bluegrass over perennial ryegrass or fine fescues.  The University of Minnesota Extension has numerous resources to help you in repair process.  Please follow these links for more information: 

Purchasing Turfgrass Seed

Finding the Right Grass Seed

Renovating an Existing Lawn

Lawn Diseases

Weed Control

Finally, feel free to reach out if we can be of help.  You can contact me directly at: sjbauer@umn.edu or 763-767-3518

Lawn Care Survey for Twin Cities Residents

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Dear Twin Cities Resident,

Graduate student Madeline Leslie is offering a lawn care survey (with prizes) to collect data for a Master’s degree thesis project.  If you have time please complete the survey below to provide information on your lawn care practices.  

Lawn Care Survey   

Information on the project:
Madeline Leslie is a graduate student in Applied Plant Sciences at the University of Minnesota. Her thesis project involves conducting a survey in order to learn more about what lawn maintenance practices residents use most often in the Twin Cities Metro area; this will also help inform university extension and outreach efforts. The survey is short, and should take approximately 10 minutes to complete, including watching a 4 minute video. As an incentive to participants, every respondent will have their names entered (if they choose) in a drawing for a $50 gift card to either Amazon.com or Target. The drawing will be held in mid August.