Golfdom, April 2010

only has he found that control is even better than when he previously only sprayed during the summer but his course requires fewer chemicals He estimates his savings at 20000 a year In conjunction with the new way of battling the disease Mathews has also changed the way his turf receives nitrogen Weve had crazy summers with too many variables with our slow release fertilizers he says As a result 79 percent of his nitrogen applications are in ready available form and 21 percent are slow release products He makes nitrogen applications once a month Mike Boehm professor and chair of the plant pathology department The Ohio State University says researchers stumbled across the possibility of a spring or fall application controlling dollar spot back in 1999 The department was rotating turf plots for disease trials and some received no fungicide applications in order to prevent carryover from one study to the next It was then that Boehm and others realized that plots that didnt receive chemical applications didnt show signs of dollar spot Thats the way research happens Boehm says If you keep your eyes open you might see something At the same time says Boehm turfgrass researcher Joe Vargas at Michigan State University saw the same results with early season applications of chlorothalonil based products Soon leading researchers such as Rutgers Universitys Bruce Clarke Purdue Universitys Rick Latin and Penn State Universitys John Kaminski were conducting their own experiments By 2005 several fungicide manufacturers were taking part in the research Their products had an impact This isnt chemical company specific Boehm says What is specific to make the program work though is for superintendents to have a handle on five areas of information Boehm said knowing the historical trends for heat humidity and precipitation as well as the fertilization status of the turf and the frequency of plant growth regulators use is vital The goal is to determine when the pathogen is active and doing damage to the plant not when the plant shows the damage Boehm says If you know when it interacts with the host youre better equipped to manage the pathogen he adds Mathews describes it this way Its a lot easier to control a 5 year old child than a 25 year old child All the research has not determined why applying fungicides in fall and spring is so effective Boehm said some postulate that the timing inhibits the waking up of the disease or possibly in the case of the fall application makes it less winter hardy Continued on page 26 w w w g o l f d o m c o m Golfdom 25 B Y A N T H O N Y P I O P P I C O N T R I B U T I N G E D I T O R ONTROL More superintendents are finding that it pays to spray in the spring to control dollar spot PHOTO COURTESY OKLAHOMA STATE UNIVERSITY