Tebuconazole (Folicur®) shows potential in the control of white rot (Sclerotium cepivorum) in garlic in subtropical Queensland, Australia

Abstract

White rot (Sclerotium cepivorum) is a major disease of garlic and onions in the Lockyer Valley in S.E. Queensland where garlic (Allium sativum) is a minor industry. This industry has continued to diminish in recent years due to the competition of imports and to a lesser extent the threat of white rot. As part of a small ongoing garlic research program at Gatton Research Station, chemical control of white rot is being investigated. In 1996, four rates (0.25, 0.5, 0.75 and 1.0) of tebuconazole (Folicur®) and five rates (0.5, 1.0, 1.5, 2.0 and 2.5 ) of procymidone (Sumisclex®) in the Flocol liquid formulation were applied to the cloves of the varieties Glenlarge and Southern Glen as separate treatments. An untreated control within each variety was also included. The trial was conducted in an area heavily infested with white rot. Survival counts made throughout the growth of the crop demonstrated that the tebuconazole treatments were superior in both varieties. The percentage of surviving plants at harvest for the 0.75 and 1.0 treatments of tebuconazole were 91.1 and 92.5 respectively in Glenlarge and 84.2 and 85.8 respectively in Southern Glen. The highest survival rate with the procymidone treatments was 33.6% in Glenlarge and 25.1% in Southern Glen which compared to 24.9% and 20.2% respectively in the Glenlarge and Southern Glen controls. Highest marketable yields were obtained from the highest rate of tebuconazole in Glenlarge (7.7 t/ha) and Southern Glen (8.6 t/ha) but in both cases this was not significantly higher than the 0.75 rate. The respective controls in Glenlarge and Southern Glen produced 1.6 and 0.9 t/ha and the highest yields from the best procymidone treatment were 2.5 t/ha (Glenlarge) and 2.1 t/ha (Southern Glen). Tebuconazole at a rate of 0.75 has demonstrated effective control of white rot in S.E. Queensland.