Fungicides, rates, and timing for leaf curl control on nectarine

Demethylation inhibitor (DMI) fungicides were evaluated in 1986 and 1987 on nectarine against leaf curl disease (Taphrina deformans) and were compared with protectant fungicides. Different rates and timings were evaluated. Primary infection occurred during bloom in both years, on 15-18 September 1986 (leaves unfolding) and on 8-9 September 1987 (leaflets protruding 0-5 mm from buds). DMI fungicides were generally ineffective in all trials except at very high rates. By contrast, protectant fungicides at 85% leaf fall (chlorothalonil plus cupric hydroxide), leafbud movement (captafol, chlorothalonil, or cupric hydroxide), or blossom (chlorothalonil) reduced disease to 0-3%. Eradicative spraying with captafol after infection had occurred was only partially effective in reducing disease.