Evaluation of fungicides, applied at sowing, for control of blackleg in rapeseed

The effects of 4 fungicides, applied at sowing, on the severity of blackleg disease of rapeseed were studied in the field. The systemic triazole fungicide flutriafol, coated on superphosphate fertiliser and applied as an in-furrow treatment at 250 g a.i./ha, was the most effective treatment and gave appreciable disease control and markedly increased yields. The fertiliser treatment was much more effective than a fungicide-coated sand granule treatment (also at 250 g a.i./ha). When applied as fertiliser, triadimefon (250 g a.i./ha) and procymidone (2.5 kg a.i./ha) were much less effective than flutriafol (250 g a.i./ha). When applied as granules flutriafol (2 kg a.i./ha) gave the best control of disease, and increased yields over the nil fungicide treatment (4.4 v. 3.41 t/ha, P<0.05). Triadimefon (2 kg a.i./ha) was less effective than flutriafol and diniconazole (2 kg a.i./ha) had no effect on disease. Seed dressings of the 4 fungicides were phytotoxic, and had little effect on blackleg.