Conference season is upon us. Winter is the time to attend seminars and conferences, learn, and get recertified. Many learn by net-working in the hallway, over dinner or enjoying a libation among colleagues. I recently attended the Eastern Shore Association of Golf Course Superintendents Conference in Ocean City, MD, and a Genesis Customer Education Seminar in Dover, DE. I picked up some very good information from several speakers. In this E-Blast, I would like to review a few insights presented by Mr. Steven McDonald (President, Turfgrass Disease Solutions) and Mr. Ted Huhn (Sr. Sales Specialist, BASF) on the subject of common bermudagrass (aka wiregrass) control.
Common bermudagrass/wiregrass is about the nastiest weed of lawns and golf turfs. Superintendents are experimenting with Pylex (topramezone) in close cut bentgrass turf, but higher cut roughs and lawns are more amenable to this herbicide. I only had two years at UM working with Pylex. My limited research dealt with hitting wiregrass with Pylex at complete green-up in June. Results appeared to be excellent, but not definitive nor time-tested. More recently, I worked two summers for an LCO doing customer service calls and all attempts using late summer Pylex applications to lawns met with unacceptable control. From what I learned, Pylex is not the “silver bullet” for wiregrass control, but a tool in a “war of suppression.”
Borrowing from presentations by Steve and Ted, I will summarize the state of the situation for roughs and lawns. Pylex applications normally begin in late summer to provide time for overseeding. Three Pylex applications will be needed in the first season of use. Pylex should to be applied at 1.5 oz. product/ACRE and tank mixed with either crop oil or methylated seed oil plus Turflon (triclopyr; 32 oz. prod./ acre). The second application should be made again in 21-28 days. Crop oil or methylated seed oil (0.5% v/v) should be in the mix with Pylex to ensure best possible uptake of the herbicide. The third application, in which the treated site has been overseeded and seedlings are present, must exclude the Turflon component, since Turflon is potentially phytotoxic to seedlings. There will be wiregrass survivors! If you had ever looked closely at the many thick stolons, and dug down to view the underground rhizomes, it would be hard to believe that any herbicide could possibly translocate throughout all stems at lethal levels. Another Pylex application, therefore, usually is needed the following June, when wiregrass has achieved full green-up and leaf expansion. Spot-treating thereafter, if logistically possible, is the best way to go.
Steve proposed for situations in which wiregrass dominates, a “non-selective approach” as a starter. Regrettably, wiregrass cannot be eliminated, even via fumigation. In a non-selective program, apply Round-up (glyphosate at full label rate) mixed with the grass herbicide Fusilade T&O (fluazifop; 16 oz.prod./A). A second application, within 21 to 28 days, is necessary. In the second application, the Fusilade T&O rate should be reduced to 8.0 oz. prod./A ,since a higher rate could provide enough soil residual to negatively impact rooting of sod and seedlings. Regardless, wiregrass will recover, but it may take 1 to 2 years to see it once again explode out of the ground. When noted, use a selective spot-treatment program with either Pylex + Turflon or Pylex + Acclaim Extra (22 oz prod./A).
Digging is a laborious option where wiregrass is isolated in a few small spots. Before excavation, killing stolon and basal stem tissue is needed to outline the area to be removed and to ensure there is no hidden wiregrass in peripheral areas. Isolated wiregrass patches should be spot-treated with Round-up + Fusilade T& O; be sure to extend the spray swath 6” or more beyond all visible stolons. It is best to wait 21 to 28 days to ensure there is no wiregrass recovery within or along peripheral areas. Excavate as far down as you can find roots and rhizomes – and then go a little deeper. Carefully contain and discard the noxious wiregrass debris and soil. Do not compost or throw debris into some lonely spot near turf, where it can survive and spread.
Wiregrass can be introduced from “some” sod farms in southern areas of our region where it is naturally commonplace. I know firsthand, since it happened to me! When spec’ing a big job, be sure to visit the sod farm and carefully inspect the field destined to be harvested for your job site. Look carefully at areas adjacent to dirt roads, in and around fields, ditches and other nearby waste sites. Maryland Certified Tall Fescue generally is seeded using a 90% tall fescue + 10% Kentucky bluegrass mix. In some situations, Kentucky bluegrass may dominate before it is harvested. So, while you are there, also look carefully at the sod itself to make sure tall fescue is the dominant component of the mix.