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, signifi cantly delaying the onset of disease and the level of foliage blight a t the end of the season compared with the untreated control. Compared with mancozeb, fluazinam significantly delayed onset in 4 of the 5 yea rs while the level of foliage blight at the end of the season was sign ificantly reduced in 1989 and 1990. Fluazinam did not significantly de lay 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 signific ant differences in tuber blight control could be found between fluazin am and the phenylamide programme. The relative effects of fluazinam, m ancozeb and the phenylamide-based programme on total and marketable yi elds were inconsistent and varied between years. Phenylamide-resistant inoculum was present in the trial area in all 5 years of the experime nts.