Papaya foot rot reduction under nursery conditions with application of potassium, calcium, or magnesium phosphate/Aplicacao de fosfito de potassio, calcio ou magnesio para a reducao da podridao-do-pe do mamoeiro em casa de vegetacao

• Published in: Ciência rural Vol. 39; no. 8; p. 2309
• Main Authors: Dianese, Alexei de Campos, Blum, Luiz Eduardo Bassay, Dutra, Jaqueline Barbosa, Lopes, Leonardo Ferreira
• Format: Journal Article
• Language: Spanish
• Published: Universidade Federal de Santa Maria 01.11.2009
• Subjects: Atmospheric carbon dioxide; Phosphates; Phosphonates
• ISSN: 0103-8478

Foot rot, caused by Phytophthora palmivora, is an important disease of papaya (Carica papaya). Disease control is of extreme importance to reduce losses and to increase productivity. Seven phosphites were tested in greenhouse using papaya seedlings (~ 10cm height) of the cultivar 'Tailandia Roxao'. Experiments were conducted with the following objectives: to determine the most effective method for phosphite application (spray or drench) to reduce disease; to determine the period for phosphite application before pathogen inoculation on plants; to determine the number of phosphite applications; to determine the effects of different phosphites on disease severity. Data from experiments showed that: spraying of aerial plant parts was the most adequate method for phosphite application; phosphites should be applied at least 48h before the inoculation of the pathogen on plants; two weekly phosphite sprays for three consecutive weeks before the pathogen inoculation on plants reduced disease, and; fosetylAl and all tested phosphites [phosphite A (40% P2O5 + 20% K2O, 150mL c.p. 100L-1), B (40% P2O5 + 20% K2O, 250mL), C (10% P2O5 + 6% Ca, 400mL), D (20% P2O5 + 20% K2O, 200mL), E (40% P2O5 + 6% Mg, 150mL), F (30% P2O5 + 20% K2O, 175mL), G (20% P2O5 + 20% K2O, 200mL)] reduced disease severity. Key words: Carica papaya, Phytophthora palmivora, phosphonate. O controle da podridao-do-pe (Phytophthora palmivora) do mamoeiro (Carica papaya) e essencial para reduzir perdas e aumentar a produtividade dos plantios. Sete fosfitos foram avaliados em plantulas (~10cm de altura) de mamoeiro da cultivar 'Tailandia Roxao'. Experimentos foram conduzidos com os seguintes objetivos: determinar a melhor forma de aplicacao do fosfito (pulverizacao ou rega); determinar o melhor periodo previo a inoculacao do patogeno para aplicacao do fosfito; determinar a quantidade de aplicacoes de fosfito; determinar o efeito de diferentes fosfitos sobre a doenca. Os resultados dos testes mostraram que: o metodo mais adequado para aplicacao dos fosfitos foi a pulverizacao da parte aerea; a aplicacao dos fosfitos deve ocorrer com pelo menos 48h antes da inoculacao do patogeno; duas pulverizacoes semanais por tres semanas consecutivas antes da inoculacao do patogeno reduziram a doenca; e fosetylAl e todos os fosfitos testados [fosfito A (40% P2O5 + 20% K2O, 150mL p.c. 100L-1), B (40% P2O5 + 20% K2O, 250mL), C (10% P2O5 + 6% Ca, 400mL), D (20% P2O5 + 20% K2O, 200mL), E (40% P2O5 + 6% Mg, 150mL), F (30% P2O5 + 20% K2O, 175mL), G (20% P2O5 + 20% K2O, 200mL)] reduziram a doenca. Palavras-chave: Carica papaya, Phytophthora palmivora, fosfonato.