Ron Calhoun, Environmental Turfgrass Specialist

WANT TO KNOW BEST TIME TO CONTROL WEEDS?

MSU INTRODUCES NEW TOOLS TO HELP TRACK WEED LIFE CYCLES

Ron Calhoun says that understanding the life cycles of weeds is the first and most important step in developing effective control programs. "As a rule, folks don't start to try to figure out what type of weed it is or how to control it until the weed starts to flower," Calhoun says. "But, for example, by the time an annual weed starts to flower, it's usually too far into the weed's life cycle for herbicide applications to be effective."

"Fall is far and away the best time to control broadleaf weeds in turfgrass, but for many perennial weeds, good control can also be accomplished by applying herbicide during or just after flowering," he adds.

In an effort to help guide turfgrass and landscape professionals in developing effective weed management programs, Calhoun has developed a Web-based program to predict weed flowering times. Weed life cycle predictions are calculated on the basis of the season and weather data collected from the Michigan automated weather station network located across the state and weather centers in Ohio and northern Indiana.
"The Web program bases its predictions on growing degree-days instead of an arbitrary calendar date, which may or may not be accurate for any given year in a region. This program bases its information on actual data collected from the weather stations," he says. "When you enter your zip code on the Web site, it pulls weather information from the weather station closest to your area and creates a customized report for bug activity, crabgrass emergence, disease breakout and other situations in your area. This is the first program of its kind."

Growers, golf course managers, turfgrass and landscape professionals, and those involved in other green industry-related professions can access the growing degree-day tracker Web site to learn more about available predictive models and how to calculate growing degree-days, and to sign up to receive customized updates for their area. The Web site address is www.gddtracker.net. There is no charge to access the site or to sign up for the customized reports.

Calhoun and his colleagues have designed a poster illustrating the growing degree-day calendar and relative flowering times for common turf weeds. Posters cost $5 each ($50 for a laminated poster) plus $2.95 shipping and handling. For ordering information, e-mail info@gddtracker.net or call the Michigan Turfgrass Foundation at 517-321-1660.

The poster and Web site project received funding from the Michigan Turfgrass Foundation and Project GREEEN, Michigan's plant agriculture initiative at MSU.

2007 Research Extension Proposal

Continuing Projects

Weed Garden: In 1998 a weed garden was established at the south end of the turf center property. This display has been very useful for learning the identification of broadleaf and grassy weeds of turf. Proper identification is the first step to control. Although very labor intensive, the garden has been very useful during training sessions with extension agents, and visits from lawncare operators. The garden is a major component of the Weed ID workshop held on the afternoon of field day and has served as a ready source of plant material for the Turfgrass Pest Management class and Turfgrass Short Course, which are taught each fall. The number of specimens was increased and the quality of specimens was also improved over the last several years. Due to the success of the weed garden, permanent plastic signs have been made to identify the plots year-round. Additionally, enough plant material has been generated to ensure that live plant samples will be used for the Turfgrass Weed ID and Management Workshop at the MTF Conference. This will be a tremendous addition to the workshop and has resulted in an increase in re-certification credits awarded to the class as well as 0.35 CEU’s from the GCSAA.

Best Management Practices for Weed Control: This project has been completed. Please see the attached peer-reviewed article that was generated from this project. This project primarily funded by the MTF.

T3 Weed Protocols: The T3 weed program started in 1997 has been very popular. A list of difficult-to-control weeds for Michigan has been developed. Through this research we have developed recommendations for several speedwells species, ground ivy, and clover. We have continued work with ground ivy and initiated studies on wild violet, quackgrass, and equisetum. The turfgrass fact sheet ‘Ground Ivy Control’ is a direct result of our T3 Weed research. A large study was conducted in 2003-05 to evaluate herbicide replacements for clopyralid, a common ingredient in many commercial herbicides. Primarily, this involved stand-alone and tankmix combination with fluroxypyr. This compound is also in the pyridine family and demonstrated very good white clover and dandelion control. This information will be very useful in developing future weed control recommendations with the residential removal of clopyralid. Further studies are planned to examine turfgrass tolerance for the common cool-season species.

Several weed areas were established in 2002 to accommodate future research needs. Forty pounds of crabgrass seed were slit-seeded into a 1.5-acre area at the south end of the turf center. Additionally, a dandelion, broadleaf plantain and white clover combination area was established after Field Day in August. Currently, most of the broadleaf weed control trials are conducted off-site. These new areas should facilitate our ability to present results at Field Days (this area has matured nicely and was used for Field Day in 2004 – 2006).

Studies completed for knotweed, wild violet, crabgrass, broadleaf plantain, germander and creeping speedwell.

Annual and Rough Bluegrass Management (Poa annua, Poa trivialis): Turfgrass management professionals, including golf course superintendents, sports field managers, sod producers, and lawncare operators, have spent years trying to eradicate annual bluegrass from their turf swards. Annual bluegrass (Poa) is one of the most invasive weeds in turfgrass stands. It is also one of the most difficult to control. Objections to Poa in turfgrass stands include its prolific seed production, apple green color, and the bare patches that can be left behind when the Poa is selectively removed by summer stress or disease pressure. In recent years, rough bluegrass (Poa trivialis) has become more prevalent on sod farms and fairways. Our research will focus primarily on postemergence removal and management practices to diminish the impact of these undesired grasses. We recently completed a six-year study evaluating timing of PGR applications in the spring for effective and safe annual bluegrass seedhead suppression.


New Projects
 
Title: Programs Approach for Poa annua Control
Cooperator: Ronald Calhoun, Michigan State University
Location: Hancock Turfgrass Research Center
Timeline: Fall 2006-Spring 2010

Objectives: Determine the effectiveness of various Poa control programs and program combinations for limiting Poa annua infestation in a newly established creeping bentgrass fairway. Identify most effective treatment programs for minimizing Poa annua populations over a three-year period after establishment.

Experimental Design: 2x2x2 Factorial RCB
Number of Replications: 3
Application Equipment: Backpack sprayer (8002VS flat fan)
Crop: Creeping Bentgrass (established fall 2006)
Mowing Height: 0.5” (Fairway)

Treatments:  

Title: On-Site Demonstration of HM9930 for Selective Poa annua Removal
Cooperator: Ronald Calhoun, Michigan State University
Location: Forest Akers, Kalamazoo Country Club, Lugnuts Stadium, HTRC
Timeline: Fall 2006 – 2007

Objectives: HM9930 is an experimental herbicide that has shown very promising results in preliminary trials at MSU for removing Poa annua from creeping bentgrass. The demonstration plots will help determine the effectiveness of HM9930 for removing existing populations of Poa annua in creeping bentgrass putting greens and in a KBG baseball infield. Plots will be established during the fall of 2006.

Archived Proposals

2006 Research Extention Proposal 

2007 Research Extention Proposal