Tratamento químico de sementes de mamão visando ao controle de Rhizoctonia solani

Abstract

Parte da Dissertação de Mestrado da primeira autora. Universidade Estadual do Norte Fluminense. Campos dos Goytacazes RJ. 2007. RESUMOAvaliou-se a eficiência do tratamento de sementes de mamoeiro com fungicidas no controle de Rhizoctonia solani. Foram realizados dois experimentos nos quais as sementes foram tratadas com fungicidas nas seguintes doses (g i.a. kg -1 de sementes): triadimenol (0,5 e 1,0), pencycuron (1,0 e 2,0), thiabendazole (5,0 e 10,0), fludioxonil (0,25 e 0,50), difeconazole (1,0 e 2,0), captan (5,0), tolylfluanid (2,5), captan + tolylfluanid (5,0+2,5). Na testemunha, as sementes foram tratadas apenas com água. Em laboratório, avaliou-se o vigor (%) e a germinação (%) das sementes. Em casa-de-vegetação, efetuou-se o semeio das sementes tratadas e não-tratadas em substrato infestado com micélio de R..solani AG1-IB. Sementes não tratadas foram plantadas em substrato infestado e não infestado (testemunhas). Não se observaram sintomas de toxidez nas plântulas cujas sementes foram tratadas com os fungicidas testados. Em casa-de-vegetação, a exceção de difeconazole, todos os demais fungicidas reduziram eficientemente a morte de plântulas em pré-emergência e apresentaram elevada emergência de plântulas (%), igualando-se a testemunha em substrato não infestado, com destaque para a mistura tolylfluanid + captan, que diferiu estatisticamente da testemunha em substrato infestado. Já, quanto ao percentual de plântulas com tombamento em pós-emergência, controle satisfatório foi obtido somente quando as sementes foram plantadas em substrato não infestado. Palavras-chave: Carica papaya, damping off, fungicidas. ABSTRACT Chemical treatment of papaya seeds to control Rhizoctonia solaniThe efficiency of fungicides applied on papaya seeds to control Rhizoctonia solani was evaluated in two experiments. Papaya seeds were treated with fungicides (grams of active ingredient kg -1 of seeds): triadimenol (0,5 and 1,0), pencycuron (1.0 and 2.0), thiabendazole (5,0 and 10,0), fludioxonil (0,25 and 0,50), difeconazole (1.0 and 2.0), captan (5.0), tolylfluanid (2.5) and captan + tolylfluanid (5.0 + 2.5) and controls (without fungicides). The vigor (seed germination percentage at the first count) and germination (%) of the seeds were evaluated in laboratory. In greenhouse, seeds were sowed in substrate infested with fungus mycelia, and in the controls, untreated seeds were sowed in infested and uninfested substrate. Seeds without chemical treatment were planted in infested and uninfested substrate as the controls. Toxicity symptoms on the seedlings were not observed for all treatments. Except for difeconazole, all products were efficient in controlling the death of seedlings in pre emergence and increased the emergence of plants in both experiments in greenhouse conditions, but satisfactory post-emergence damping-off control was achieved only by use of uninfested substrate.

Pea seed treatment for Rhizoctonia solani control

“…However, in the first count test, the control gave the best result, together with Metalaxyl-M + Fludioxonil and Iprodione + Thiram, with no differences between them (p ≤ 0.05). As observed for germination, Captan also adversely affected seed vigor in both tests, corroborating with results from Campos et al (2009) for papaya seeds, where Captan also adversely affected seed vigor. There were no statistical differences between treatments for the electrical conductivity test in contrast to the results obtained by Nascimento and Cícero (1991) for pea seeds.…”

Chemical treatment of papaya seeds aiming at long-term storage and control of damping off

“…suggested the use of captan for papaya seed protection and Posse (2005) reported that benomyl and the mixture (iprodione + benomyl) were effective in the control of papaya damping off. Campos et al (2009) evaluated ready-to-use formulations of the fungicides captan, tolylfluanid, thiabendazole, difeconazole, pencycuron and fludioxonil and concluded that they were not toxic to the seeds and seedlings of papaya at the tested concentrations.…”