Resumo

YANEZ JUAREZ, Moisés Gilberto et al. Effect of Bicarbonates on the control of powdery mildew (Oidium sp.) in Cucumber (Cucumis sativus L.). Rev. Mex. Cienc. Agríc [online]. 2014, vol.5, n.6, pp.991-1000. ISSN 2007-0934.

To determine the efficacy of potassium bicarbonate (BP) and sodium bicarbonate (BS) in the control of powdery mildew (Oidium sp.) in cucumber plants, an investigation was conducted under greenhouse conditions cultivating plants of cv 'Poinsett 76' in pots with a capacity of 4.5 kg of chromic vertisol soil. Every third day was fertilized with a composed solution of 101 g KNO₃, 200 g of CaNO₃, 136 g KH₂PO and 246 g MgSO₄, diluted in 100 liters of water. Treatments were 2, 4 and 6 g L^-1 of BP water and 2 and 4 g L^-1 BS, same as with manual spray applied onto foliage to drip point. At 31, 33 and 35 days after the first application (ddpa) the number of leaves, number of diseased leaves, incidence and severity of powdery mildew on leaves of the main stem was evaluated. The number of leaves was not affected by potassium or sodium bicarbonate; the highest decrease of diseased leaves (94.6, 93.3 and 92.4%) was obtained with 4 g L^-1 of BP, at the respective 31, 33 and 35 ddpa. The maximum decrease (48.4 percentage points) of mildew incidence was observed in plants of 4 g L^-1 BP (p≤ 0.05); with the same dose, the severity of powdery mildew decreased to 84.3 and 60.5 percentage points in leaves three and four, respectively; while in leaf five the disease was zero.

Palavras-chave : Cucurbitaceous; efficacy; antifungal properties; disease.

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