Control effecacy of the mixture of salicylic acid and prochloraz on anthracnose of Camellia oleifera

To determine the control efficacy of the mixture of salicylic acid and prochloraz on anthracnose of Camellia oleifera, the efficacy tests were conducted both in the lab and in the field. In the lab, leaves detached from seedlings of C. oleifera were inoculated with Colletotrichum gloeosporioides for bioassays. The field plot assays were employed for the verification of control efficacy. Lab tests showed the control efficacy of 150 mg/L salicylic acid mixed with 200 mg/L prochloraz (C2) was significantly higher than that of 200 mg/L prochloraz (P2), and the mixture presented a synergistic effect. The synergic ratio of the C2 treatment was 1.42 at ten days after the second spray. Twenty days after the second spray, the control efficacy of the C2 treatment was maintained at 57.26%, significantly higher than that of the P2 treatment at 27.49%. Twenty-eight days after the second spray in the field trial, the control efficacy of C2 treatment was 72.86%, while the efficacy in P2 treatment was only 46.54%, consistent with the observation in the lab. The results demonstrated that the mixture of salicylic acid and prochloraz enhances the control efficacy and prolongs the effective duration of prochloraz against anthracnose of C. oleifera. Thus, the application of the mixtures will reduce the use frequency and concentration of prochloraz and achieve the purpose of reducing pesticide use and increasing efficiency.