Further Studies on the Control of Target Spot with Fungicides

Efficacy of recommended and candidate fungicides as well as fungicide application timing for the control of target spot on cotton was evaluated in a series of trials in 2013 at the Gulf Coast Research and Extension Center.  Few differences in target spot control was noted between recommended rates of Headline, Quadris and Twinline.  Optimal application rate for Headline appears to be in the range of 9 fl oz/A as there is little improvement in efficacy when the application rate is increased to 12 fl oz/A.  Addition of Bravo WeatherStik (chlorothalonil) with Headline tank mixtures did not enhance disease control but may prove useful for resistance management.  On Phytogen 499, applications of Headline at 4 and 6 weeks after first bloom gave better disease control through late August as compared with earlier and later application timings, while poorest target spot control on DPL 1252 was obtained with application at pin head square and 2^nd week of bloom.  By mid-September, application timing did significantly impact target spot control.  Several candidate fungicides proved as efficacious in controlling target spot as the above registered fungicides.