Golfdom, July 2017

TIMELY TURF ADVICE by Clark Throssell Ph D Clark Talks Turf Battling goosegrass Scott McElroy Ph D is a turfgrass weed scientist at Auburn University Scott conducts numerous field and laboratory experiments each year to develop weed control strategies for golf courses You may reach Scott at jsm0010@ auburn edu for more information Q How widespread is goosegrass on golf courses in your region Youll find it on nearly all golf courses regardless of budget Once goosegrass is present on a green it quickly spreads to all greens It usually gets a foothold in the green surround and spreads to the greens from there because it can tolerate close mowing heights without a problem Goosegrass is becoming more widely distributed throughout the country possibly because summers are becoming hotter and longer Q What do you recommend for postemergent goosegrass control on a bermudagrass green Currently Revolver foramsulfuron Bayer is the only herbicide labelled for postemergent goosegrass Elusine indica control on bermudagrass putting greens Research has shown that application at 04 fl oz per 1000 sq ft every two to three weeks with a total of three applications works well to control goosegrass The key is to make the first application early in the season while the goosegrass is small Its important that the golf industry find additional herbicides for postemergent goosegrass control because in my opinion the probability of goosegrass developing resistance to Revolver is high Combinations of Revolver plus Dismiss sulfentrazone FMC in field research are effective but Dismiss is not labeled for use on bermudagrass putting greens Illoxan diclofop methyl Bayer is no longer offered for sale but superintendents can use existing stocks for postemergent goosegrass control on putting greens For season long control of goosegrass on bermudagrass putting greens I recommend split applications of Andersons Goosegrass and Crabgrass Control bensulide and oxadiazon Andersons according to label directions followed by Revolver applied for postemergent control as described above Q What do you recommend for postemergent goosegrass control in bermudagrass green surrounds A tank mix of Revolver plus Dismiss is effective I have seen excellent goosegrass control in bermudagrass green surrounds with Pylex topramezone BASF Pylex functions as an early postemergent herbicide with some preemergent activity so apply when the goosegrass is small Be aware that Pylex causes whitening of the bermudagrass that lasts two to three weeks so use lower rates You can reduce the whitening by adding a chelated iron product to the Pylex One application of Pylex wont damage bermudagrass permanently but more than one application can reduce bermudagrass density For preemergent goosegrass control in bermudagrass surrounds Ronstar oxadiazon Bayer and Specticle indaziflam Bayer are effective Dont let any of the Specticle reach the green because damage will occur Q What do you recommend for postemergent goosegrass control on creeping bentgrass greens To my knowledge there are no postemergent herbicides labelled for goosegrass control on creeping bentgrass greens The best option for creeping bentgrass greens is to split applications of Andersons Goosegrass and Crabgrass Control bensulide and oxadiazon Andersons according to label directions My observation is that the more thatch that is present the more goosegrass that is present Cultural practices that lead to a firm putting surface and controlling thatch lead to less goosegrass Q What do you recommend for postemergent goosegrass control on bermudagrass tees and fairways Dismiss or Revolver are good options on tees In spring an application of Ronstar as a preemergent reduces problems later in the season Goosegrass on fairways is not as big a problem because there is a wide range of preemergent herbicides available to control goosegrass So scout on a regular basis and control goosegrass postemergently as it is observed Q Is there anything else you would like to add Herbicide resistant goosegrass has been documented on several golf courses To reduce the chances of herbicide resistant goosegrass developing use both preemergent and postemergent herbicides to control goosegrass Use multiple modes of action when selecting both preemergent and postemergent herbicides Clark Throssell Ph D loves to talk turf Contact him at clarkthrossell@ bresnan net July 2017 Golfdom 37 Golfdom com