Evaluation of soil-drench control system against Ceratocystis canker of fig with fungicide available up to the day before harvesting

Abstract

Ceratocystis canker is one of the most serious diseases of figs, Ficus carica, in Japan. Some fungicides, such as triflumizole WP (T) and thiophanate-methyl WP (TM), have been drenched monthly to control the disease. However, these fungicides are not applied during harvest season because of registration restrictions, and losses of soil drench during harvest season were feared. We evaluated effectiveness of control with soil drenches of the newly registered tebuconazole WP (TE), which can be used up to the day before harvest. We planted fig cuttings in the soil contaminated with Ceratocystis ficicola, causal agent of Ceratocystis canker. Treatments were as follows: 1) control, 2) existing treatment (T and TM drenched bimonthly from April to October, except for the harvest period from August to October), 3) existing treatment plus TE at harvest (TE drenched monthly from August to October). Cumulative death rates of plants in each treatment were evaluated for 3 years. More than half of the plants died in the control, and less than half of plants died in the existing treatment. On the contrary, no plants died in the existing treatment plus TE. These results suggest that existing treatment plus TE possess high control effect against the disease.