ACTIVITY OF FLUAZINAM AGAINST LATE BLIGHT OF POTATOES

The effectiveness of fluazinam in controlling late blight of potatoes was evaluated in studies conducted over a 5-year period (1989 to 1993). In all years, fluazinam gave good control of foliage blight, significantly delaying the onset of disease and the level of foliage blight at the end of the season compared with the untreated control. Compared with mancozeb, fluazinam significantly delayed onset in 4 of the 5 years while the level of foliage blight at the end of the season was significantly reduced in 1989 and 1990. Fluazinam did not significantly delay the onset of disease or reduce the level of foliage blight at the end of the season when compared with a pre-pack phenylamide + mancozeb programme (first three sprays) followed by mancozeb alone. Fluazinam was as effective as mancozeb in controlling tuber blight in 4 of the 5 years and was significantly better than mancozeb in 1992. No significant differences in tuber blight control could be found between fluazinam and the phenylamide programme. The relative effects of fluazinam, mancozeb and the phenylamide-based programme on total and marketable yields were inconsistent and varied between years. Phenylamide-resistant inoculum was present in the trial area in all 5 years of the experiments.