Biocontrol of seed pathogens and growth promotion of common bean seedlings by Trichoderma harzianum

Abstract

-The objective of this work was to evaluate isolates of Trichoderma harzianum regarding biocontrol of common bean seed-borne pathogens, plant growth promotion, and rhizosphere competence. Five isolates of T. harzianum were evaluated and compared with commercial isolate (Ecotrich), Carboxin+Thiram, and an absolute control. Bean seeds of the cultivar Jalo Precoce, contaminated with Aspergillus, Cladosporium, and Sclerotinia sclerotiorum, were microbiolized with antagonists, and seed health tests were carried out. Isolates were evaluated on autoclaved substrate and in field conditions. Ten days after sowing (DAS), plant length was measured. To test rhizosphere competence, isolates were applied in boxes containing autoclaved washed sand, and root colonization was evaluated at 10 DAS, using five plants per box. The most effective isolates in the seed health tests were: CEN287 and CEN289 to control Aspergillus; the commercial isolate to control Cladosporium; and CEN287 and CEN316 to control S. sclerotiorum. Isolates CEN289 and CEN290 promoted bean growth in greenhouse and field. Seed treatment with T. harzianum reduces the incidence of Aspergillus, Cladosporium, and S. sclerotiorum in 'Jalo Precoce' common bean seeds.

Biological control of Fusarium oxysporum f. sp. phaseoli by Trichoderma harzianum and its use for common bean seed treatment

“…& W.C. Snyder. This fungus causes the Fusarium wilt disease, and is among the most damaging pathogens of common bean (Phaseolus vulgaris L.) in Brazil (Carvalho et al, 2011a). Following its introduction into an area, Fusarium wilt may appear in small, isolated foci and, after several seasons, spread throughout the entire area (Abawi & Pastor-Corrales, 1990).…”

“…Fungicides are not recommended for the management of vascular wilts (except for seed treatment), since they may not prevent plant infection and subsequent phloem colonization. Biological control with Trichoderma species has contributed to reduce Fusarium wilt incidence mainly when applied on seeds (Carvalho et al, 2011a;Carvalho et al, 2011b).…”

Regimes de luz na produção de conídios de Trichoderma harzianum para controle do mofo branco em feijoeiro

“…Inibição de germinação de escleródios (%) (1) O efeito colonizador dos escleródios obtido para CEN287 e CEN316 já era esperado, uma vez que estes isolados já foram citados como efetivos para o controle de S. sclerotiorum em sementes de feijão (Carvalho et al 2011). Entretanto, apenas CEN287 foi indiferente quanto aos regimes de luz empregados na obtenção dos conídios.…”

“…Por se tratar de isolado hábil para colonização de substratos e raízes (Carvalho et al 2011), sugere--se que este isolado tenha se adaptado à condição de escuro, inclusive para seu antagonismo.…”

“…O efetivo controle do patógeno nos folíolos já era esperado para CEN287 e CEN316, pois estes isolados foram relatados como efetivos no controle de S. sclerotiorum em sementes de feijão comum cv. 'Jalo Precoce', sendo similares ao tratamento químico (Carvalho et al 2011), mesmo em condições de campo (Carvalho et al 2015).…”