Resumen

GARCIA, Rosaima  y  GARCIA, Alba. Strategies for chemical control of potato late blight on two localities of Mérida State, Venezuela. Bioagro [online]. 2004, vol.16, n.2, pp.77-83. ISSN 1316-3361.

With the purpose of finding efficient strategies for controlling potato late blight (Phytophthora infestans Mont (De Bary)), in places where this pest is endemic, trials were conducted in two commercial farms in Mérida State, Venezuela. Potato var. Granola, which is highly susceptible to late blight, was grown. A randomized complete block design with four repetitions was used and three experimental strategies of control (plus a farmer’s strategy) were evaluated. The strategies tested the following products and doses: a) Systemic: Ridomil MZ72 (metalaxyl 8% + mancozeb 64%) in 3 g/L (S₁), Curazin (cimoxanil + metiram) in 5 g/L (S₂); b) Contact: Dithane M45 (Mancozeb) in 5 g/L (C0) Daconil (clorotalonil) in 5 g/L (C₁), Bravo 500 (clorotalonil) in 5 mL/L (C₂) and the combinations: Daconil + Curazin (Cb₁) and Bravo 500 + Curazin (Cb₂). The sequence application of these products originated the following strategies: E1 = S₁ - Cb₁ - Cb₁ - S₁ - C₁ - C₁ - Cb₁, E2 = S₁ - C₂ - Cb₂ - C₂ - Cb₂ - C₂ - C₁, E3 = Cb₁ - C₁ - Cb₁ - Cb₁ - C₁ - C₁ -C₁ and the farmer’s control (E4) that includes combinations of C₀, S₂, and C₂. Significant differences among strategies were found for the area under the pest curve (AUDPC) and yield and tuber damage, resulting more efficient the strategy E3 in both localities, with lower area under the progress curve in relation to the farmer’s control and the others strategies. Likewise, a decrease on the application number from 12 to 7, with on appropriate management of fungicides, was achieved. It is suggested the incorporation of E3 as a component for integrated control of potato late blight.

Palabras clave : Phytophthora infestans; Solanum tuberosum; fungicides; fungus diseases.