The Effects of Polyoxins B and D on Alternaria Brassicae and the Blackspot of Rapeseed

The antibiotics Polyoxin AL W.P. (a.i. Polyoxin B 10%) and Polyoxin Z W.P. (a.i. Polyoxin D 2.2%) were tested as therapeutants and prophylactics in the blackspot disease of rapeseed caused by Alternaria brassicae (Berk.) Sacc. Both fungicides strongly inhibited the germination and viability of the conidia, and the growth of A. brassicae in agar. They also showed strong prophylactic and therapeutic actions on blackspot lesion development on leaves, both in the field and under laboratory conditions. It is concluded that polyoxins have the potential of being used to control the blackspot disease of rapeseed.