Field optimization of dimethomorph for the control of potato late blight Phytophthora infestans: application rate, interval, and mixtures

Aspects concerning the field use of dimethomorph for the control of foliar and tuber potato late blight were examined. When application rate and interval manipulation for a season-long dimethomorph and mancozeb mixture was performed,the rate increasing through the season and 80% of full rate programs had equal final foliar blight control as the full rate program,regardless of interval. The minimum application rate for control equivalent to the full rate program was 1.34 kg ha � 1 week � 1 . When dimethomorph was tank-mixed with one of three protectant fungicides and integrated into a chlorothalonil-based late blight control program,all programs were as effective as the season-long chlorothalonil program. None of the mixtures were more effective than the others. When tank-mixed with pyraclostrobin and alternated with chlorothalonil applications,rate reduction to 50% of full rate gave foliar blight control equivalent to a full rate,for a dimethomorph and pyraclostrobin mixture and pyraclostrobin alone. r 2003 Elsevier Science Ltd. All rights reserved.