Efficacy and Yield Protection from Fungicide Inputs for the Control of Foliar Diseases in Cotton

Studies were conducted in 2018 to determine the yield protection and efficacy of registered and experimental fungicides against target spot on PhytoGen 490 W3FE cotton at the Brewton Agricultural Research Unit (BARU) and Gulf Coast Research and Extension Center (GCREC) in Southwest Alabama. Each study was irrigated as needed and managed to maximize yield. With the exception of the 6 oz/A Priaxor + 1 pt/A Bravo WeatherStik umbrella program, remaining fungicide treatments were applied at the third and fifth week of bloom. Target spot intensity was assessed on a 1 to 10 scale at 7 to 14 day intervals at the third until the tenth or eleventh week of bloom. Final defoliation values will be presented. The level of premature defoliation attributed to target spot at both study locations differed by fungicide program. At BARU, lowest defoliation levels for the Priaxor + Bravo WeatherStik umbrella program were matched by Priaxor, Miravis TOP + Quadris, Miravis TOP, as well as multiple rates of the experimental fungicide BAS 75302F. All in-furrow (IF) and broadcast Propulse programs, Proline and Elatus failed to reduce premature defoliation when compared with the non-fungicide treated control. Efficacy of Topguard was intermediate between the non-treated control and the Priaxor + Bravo WeatherStik umbrella program. When compared with the non-treated control, significant reductions in final defoliation were obtained at GCREC with all fungicide programs except for Helmstar and Propulse IF and early post broadcast programs. Miravis TOP + Quadris provided better target spot protection than all fungicide programs except for Miravis TOP, Elatus, and Propulse IF fb Propulse fb Proline 480SC. Significant reductions in premature defoliation were also obtained with Proline 480SC, both rates of Priaxor, Amistar TOP, and the Priaxor + Bravo WeatherStik umbrella program. Yields and lint quality data will be presented.