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Goosegrass Control Research in Bermudagrass Putting Greens Using Granular PRE Herbicides
By Scott McElroy, Ph.D., Professor, Dept. of Crop, Soil and Environmental Sciences, Auburn University, and Michael Flessner, Ph.D., Assistant Professor, Dept. of Plant Pathology, Physiology and Weed Science, Virginia Tech University
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of control with AGC, and none have been found to be resistant. It is suspected that some goosegrass populations can become perennial in putting greens or that enhanced degradation of AGC occurs with continual use. No data exists to confirm either of these theories for lack of control. Nevertheless, while reports of inconsistent control are common, AGC still comes highly recommended, as it likely reduces the total goosegrass population, making further goosegrass control practices more effective. Research in 2013 demonstrated the potential for goosegrass control in bermudagrass putting greens with dithiopyr. Dithiopyr applied as a liquid,
Table 1
however, did cause unacceptable injury to some bermudagrass greens. Thus, 2014 research focused on the use of AGC and dithiopyr applied on a granular carrier.
2014 research
In 2014, research was conducted on a Tifdwarf practice green at Lagoon Park Golf Course in Montgomery, AL (special thanks to Wes Pitts and Zach Tolleson at Lagoon Park, as well as Jim DeReuil of Honours Golf, for use of this location). Herbicide treatments are listed in Table 1, along with rate and application timing. Herbicides were applied with a CO2-pressurized, small-plot backpack sprayer at 30 gallons per acre or were
Preemergence herbicide treatments evaluated in 2014 at Lagoon Park Golf Course in Montgomery, AL.
Treatment
Rate
Application Timing
Dithiopyr Granular
0.25 lb. ai/a
March 11
Anderson’s Goose and Crab
57 lb./a
April 2 and April 24
Anderson’s Goose and Crab
114 lb./a
April 2
Dithiopyr Granular
0.5 lb. ai/a
April 2
Dithiopyr Granular
0.25 lb. ai/a
April 2 and April 24
Dithiopyr Granular
0.38 lb. ai/a
April 2
Dithiopyr Granular
0.19 lb. ai/a
April 2 and April 24
Dimension 2EW
0.25 lb. ai/a
April 2 and April 24
Ronstar 2G
75 lb./a (1.5 lb. ai)
April 2 and April 24
Specticle Flo
4 fl. oz./a
April 2 and April 24
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Al abam a T ur f Ti me s > >> Spri ng 2015
oosegrass is an increasing problem in turf, especially on putting greens. One major issue is the lack of preemergence herbicides labeled for use on putting greens. Traditional preemergence herbicides such as Barricade (prodiamine), Pendulum (pendimethalin), Ronstar (oxadiazon), Specticle (indaziflam) and their comparable generic products are not labeled for use on putting greens or, in most instances, tee boxes. Closer, more frequently mowed turf simply does not develop a rootzone extensive enough to withstand such herbicides. With some products, however, the use is not as clear. Dimension, also a root-inhibiting herbicide, is not labeled for bermudagrass use on putting greens; however, on dithiopyr generic labels, it is not explicitly prohibited. Dithiopyr is also formulated on a granular carrier and sold as Dithiopyr Granular by The Anderson’s. Ronstar (specifically, Ronstar G) explicitly states that it should not be used on putting greens due to the varying cultural practices uses. The active ingredient in Ronstar, oxadiazon, is labeled for use as Anderson’s Goose and Crab (AGC), which also contains bensulide, the active ingredient in Bensumec. Simply due to the limited number of preemergence herbicides available for use on putting greens, AGC is becoming a popular choice for use on bermudagrass putting greens in the Southeast. There are a couple negatives regarding the use of AGC. First, bensulide can negatively impact roots, but it is viewed as less damaging than dinitroanilines, Dimension or Specticle. Second, AGC is reportedly inconsistent in control. My research group has followed up on numerous reports of lack