Efficacy of Foray 48B against Tortrix viridana L. (Lepidoptera Tortricidae) in a Sardinian pubescent oak forest

The possibility of controlling green oak leaf-roller moth infestations with Foray 48B (Bacillus thuringiensis Berl. subsp. kurstaki) was assessed in spring 2004 in a Sardinian pubescent oak forest. At the time of treatment, the larval density was 0.70-0.88 larvae per shoot. The insecticide was aerially sprayed at ULV in a dose of 4 l/ha (equivalent to 42.4 BIU/ha). One week later, a population reduction of 82% was observed in the treated plots. Canopy defoliation was 14% in the treated plots compared with 30% in the untreated plots. The experiment demonstrated the efficacy of Foray 48B treatment, but large-scale application requires further tests to assess the efficacy of B.t.k. in limiting oak defoliation when larval densities are high.