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 From the News Desk...Better spray coverage may improve dollar spot controlby John ReitmanGolf course superintendents are under increasing pressure to implement environmentally friendly management practices. A recent study conducted at Kansas State University indicates that selecting the right nozzle for a specific task can give superintendents one more tool in their arsenal to help them achieve that goal. In fact, according to the research, nozzle choice can help superintendents maximize fungicide efficacy while minimizing drift in the fight against diseases in turfgrass. The Kansas State research showed that many nozzles provided acceptable coverage without compromising fungicide efficacy at spray volumes as low as one-half gallon of water per 1,000 square feet. Those that provided the best spray coverage were most effective at helping control dollar spot. Kansas State professors Megan Kennelly, Ph.D., of the department of plant pathology, and Robert Wolf, Ph.D., of the department of biological and agricultural engineering, conducted the research in 2007-08. Their study comprised applying chlorothalonil to control dollar spot on greens-height A-4 creeping bentgrass. The plots at the Rocky Ford Turfgrass Research Center in Manhattan, Kan., were mowed six days per week at 0.156 inches and placed on a regular fertilization and irrigation program to simulate golf course putting conditions. They measured the results of using five types of nozzles to deliver chlorothalonil every 14 days at three different spray volumes (one-half gallon per 1,000 square feet, 1 gallon and 2 gallons) on three dates (Aug. 27, Sept. 25 and Oct. 11) in 2007 and two dates (June 17 and July 9) in 2008. The chlorothalonil rate was consistent across all dates at 1.8 ounces per 1,000 square feet. The nozzles used in the study were the XR flat-fan, TurfJet, Air Induction, Turbo TwinJet and Turbo Drop Twin Fan. The control plot was untreated throughout the duration of the study. Researchers also measured effective coverage of each nozzle at each spray volume level. The TurfJet nozzle at one-half gallon provided the lowest coverage, while the XR flat-fan nozzle showed the highest level of coverage. The research team only estimated effective coverage at the 1- and 2-gallon spray volume rates. According to the results of the study, incidence of dollar spot was less with all five nozzles with all except the TurfJet producing similar results. All of the nozzles provided statistically significant control of dollar spot over all collection dates in 2007, with the one exception being the TurfJet at a spray volume of one-half gallon on Aug. 27, 2007. The untreated plot exhibited 19.4 centers of dollar spot infection per square foot on Aug. 27, 32.6 on Sept. 25 and 2.8 on Oct. 11. The XR flat-fan and Air Induction nozzles provided the best control at one-half gallon and 1-gallon spray volumes during the first two data collection dates. The plots treated with the XR flat-fan at one-half gallon showed 1.2 centers of dollar spot on Aug. 27 and 0.4 on Sept. 25. The plot treated with the Air Induction nozzle at one-half gallon exhibited 2.8 centers of dollar spot in August and 1.3 in September. The XR plot at 1 gallon showed 5.7 centers of dollar spot in August and none in September, while the Air Induction plot at the same spray volume had 1.5 centers of dollar spot in August and 0.9 in September. There was no dollar spot in any of the treated turf plots by the October collection date. In year two of the study, the untreated plot showed 5.3 incidences of dollar spot on the June collection date and 7.4 in July. The XR, Air Induction, Turbo TwinJet and Turbo Drop Twin Fan all were effective at the half-gallon spray volume in June. However, none of the nozzles were effective at controlling dollar spot in July, leading the researchers to conclude that the chlorothalonil rate (1.8 ounces per 1,000 square feet) might have been too low. |
In other news... Study examines spring pre-stress fertility programs Research finds no correlation between biostimulant applications before spring core cultivation and recovery. Posted: 09/02/2010 Read more » Aquatrols, TurfNet present Water Week The series of five Webinars is aimed at helping superintendents manage water and soils more efficiently. Posted: 09/01/2010 Read more » News and people briefs Registration opens soon for Irrigation Show, Briggs & Stratton elects new chairman, FMC taps new director for professional solutions division Posted: 09/01/2010 Read more » GCSAA selects firm in search for new CEO Kansas City-based company will open search process for Mark Woodward's successor in October. Posted: 08/31/2010 Read more » Water foul! Research shows that droppings from non-migratory geese on turf can result in nitrogen runoff into adjacent bodies of water. Posted: 08/26/2010 Read more » Complete news index » |
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