L. Korsten et al., FIELD SPRAYS OF BACILLUS-SUBTILIS AND FUNGICIDES FOR CONTROL OF PREHARVEST FRUIT DISEASES OF AVOCADO IN SOUTH-AFRICA, Plant disease, 81(5), 1997, pp. 455-459
In 3 consecutive years, preharvest applications of Bacillus subtilis f
ield sprays integrated with copper oxychloride or benomyl consistently
reduced severity of avocado black spot (BS), caused by Pseudocercospo
ra purpurea at Omega, Republic of South Africa. Control was equal to t
hat obtained with copper oxychloride or benomyl-copper oxychloride in
the first and third years of spraying at Omega. In the second year, on
ly the integrated treatment controlled BS, while copper oxychloride pr
oved ineffective. The antagonist was applied on its own or integrated
with copper oxychloride sprays at two other geographically distinct lo
cations, Westfalia Estate and Waterval. The integrated and biological
treatments at these localities were less effective than copper oxychlo
ride sprays in controlling BS disease. Integrated control was more eff
ective than B. subtilis sprays at Westfalia. On continuation of the bi
ological spray program at Waterval for an additional three seasons, co
ntrol was as effective as copper oxychloride in the last 2 years of sp
raying. Sooty blotch (SE), caused by an Akaropeltopsis sp., was reduce
d by the integrated treatment at Omega during the second season and at
Westfalia during the first season. Although the two fungicide treatme
nts reduced SE at Omega in the first season, copper oxychloride increa
sed it above that of the control in the third season. Only the copper
oxychloride treatment reduced SE at Waterval in the third season, whil
e the B. subtilis treatment increased disease above that of the contro
l in the fourth season.