Some species of Trichoderma have successfully been used in the commercial biological control of fungal pathogens, e.g., Sclerotinia sclerotiorum, an economically important pathogen of common beans (Phaseolus vulgaris L.). The objectives of the present study were (1) to provide molecular characterization of Trichoderma strains isolated from the Brazilian Cerrado; (2) to assess the metabolic profile of each strain by means of Biolog FF Microplates; and (3) to evaluate the ability of each strain to antagonize S. sclerotiorum via the production of cell wall-degrading enzymes (CWDEs), volatile antibiotics, and dual-culture tests. Among 21 isolates, we identified 42.86% as Trichoderma asperellum, 33.33% as Trichoderma harzianum, 14.29% as Trichoderma tomentosum, 4.76% as Trichoderma koningiopsis, and 4.76% as Trichoderma erinaceum. Trichoderma asperellum showed the highest CWDE activity. However, no species secreted a specific group of CWDEs. Trichoderma asperellum 364/01, T. asperellum 483/02, and T. asperellum 356/02 exhibited high and medium specific activities for key enzymes in the mycoparasitic process, but a low capacity for antagonism. We observed no significant correlation between CWDE and antagonism, or between metabolic profile and antagonism. The diversity of Trichoderma species, and in particular of T. harzianum, was clearly reflected in their metabolic profiles. Our findings indicate that the selection of Trichoderma candidates for biological control should be based primarily on the environmental fitness of competitive isolates and the target pathogen.

-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.

RESUMOEste trabalho objetivou avaliar seis isolados de Trichoderma harzianum no controle de Fusarium oxysporum f.sp. phaseoli em sementes, e seu efeito no crescimento inicial do feijoeiro comum. Os isolados foram inicialmente confrontados in vitro com o patógeno em testes de cultura pareada e antibiose a 25ºC. Sementes sadias e artificialmente infectadas pelo patógeno foram microbiolizadas com 2 mL de suspensões dos antagonistas (2,5 x 10 8 conídios mL -1 ) para cada 100 g de sementes, em rolo de papel germtest a 20 e 25°C. Os percentuais de incidência do patógeno e de plântulas normais foram avaliados aos sete e nove dias, respectivamente. Em casa de vegetação, os isolados foram aplicados a 5 x 10 9 conídios 500 g -1 de substrato autoclavado, com avaliação do comprimento das raízes e parte aérea das plantas 11 dias após o semeio (12 plantas tratamento -1 ). Todos os isolados apresentaram antagonismo in vitro contra o patógeno. Os isolados CEN202, CEN234, CEN238, CEN240 foram superiores à testemunha no controle de F. oxysporum em sementes, reduzindo entre 35 e 51% da incidência do patógeno e proporcionando entre 73 e 81% de plântulas normais. O comprimento total das plantas com tratamento CEN239 (37,43 cm) foi superior aos demais, cujo comprimento variou entre 27,84 e 33,95 cm. Palavras-chave: Phaseolus vulgaris, controle biológico, patologia de sementes, supressão de crescimento. ABSTRACT Control of Fusarium oxysporum f.sp phaseoli in vitro and on seeds and growth promotion of common bean in early stages by Trichoderma harzianumThe objective of this study was to evaluate the antagonistic capacity of six isolates of Trichoderma harzianum against Fusarium oxysporum f.sp. phaseoli on infected seeds and its effect on the early stages of growth in bean plants. The isolates were also evaluated in dual culture assays and under in vitro antibiosis at 25ºC. Healthy and infected seeds were treated with 2 mL 100 g -1 seeds of the antagonist suspensions (2.5 x 10 8 conidia mL -1 ) for healthy evaluation using blotter method at 20 and 25°C. The percentages of pathogen incidence and normal seedlings were evaluated at seven and nine days, respectively. The isolates were applied at 5 x 10 9 conidia 500 g -1 of sterilized substrate in greenhouse. After 11 days, roots and shoots of the bean plants were measured (12 plants treatment -1 ). Every isolate of T. harzianum presented in vitro antagonism against the pathogen. The strains CEN202, CEN234, CEN238 and CEN240 offered better control of F. oxysporum on seeds than the positive check, causing a reduction between 35 and 51% in pathogen incidence and 73-81% of normal seedling emergence. The total length of the plants treated with CEN239 (37.43 cm) was longer than the other treatments, with length varying between 27.84 and 33.95 cm.

A partir de 40 amostras de solo, provenientes dos estados do Rio Grande do Sul, Minas Gerais, São Paulo, Bahia, Goiás e Tocantins, uma coleção de 230 isolados monospóricos de Trichoderma spp. foi estabelecida, usando o meio seletivo TSM. Com o objetivo de selecionarem-se isolados com potencial para controle biológico de doenças, foram conduzidos testes de pareamento de culturas em meio BDA, a 20 ºC para Sclerotinia sclerotiorum e a 25 ºC para Fusarium solani f.sp. phaseoli. Antagonismo contra os dois patógenos foi observado em 10% dos isolados. Avaliações ao microscópio eletrônico de varredura de sete isolados selecionados in vitro mostraram que nem todos promoveram o hiperparasitismo dos patógenos, sugerindo a existência de outros mecanismos de antagonismo, como antibiose ou competição.

-The objective of this work was to evaluate the effects of preceding crops and tillage systems on the incidence of Fusarium wilt (Fusarium oxysporum f. sp. phaseoli) and common bean (Phaseolus vulgaris) yield. The cultivar BRS Valente was cultivated under center-pivot irrigation in the winter seasons of 2003, 2004 and 2005, after several preceding crops established in the summer seasons. Preceding crops included the legumes Cajanus cajan (pigeon pea), Stylosanthes guianensis, and Crotalaria spectabilis; the grasses Pennisetum glaucum (millet), Sorghum bicolor (forage sorghum), Panicum maximum, and Urochloa brizantha; and a consortium of maize (Zea mays) and U. brizantha (Santa Fé system). Experiments followed a strip-plot design, with four replicates. Fusarium wilt incidence was higher in the no-tillage system. Higher disease incidences corresponded to lower bean yields in 2003 and 2004. Previous summer cropping with U. brizantha, U. brizantha + maize consortium, and millet showed the lowest disease incidence. Therefore, the choice of preceding crops must be taken into account for managing Fusarium wilt on irrigated common bean crops in the Brazilian Cerrado.Index terms: Fusarium oxysporum, Phaseolus vulgaris, crop-livestock integration, crop rotation, no-tillage, soilborne pathogen. Incidência da murcha-de-fusário e produção do feijoeiro de acordo com cultivos prévios e sistemas de preparo do soloResumo -O objetivo deste trabalho foi avaliar os efeitos de cultivos prévios e sistemas de preparo do solo sobre a incidência de murcha-de-fusário (Fusarium oxysporum f. sp. phaseoli) e a produtividade do feijoeiro-comum (Phaseolus vulgaris). A cultivar BRS Valente foi cultivada sob irrigação por pivô central nos invernos de 2003, 2004 e 2005, após diversos cultivos prévios estabelecidos no verão. Os cultivos prévios incluíram as leguminosas Cajanus cajan (guandu), Stylosanthes guianensis e Crotalaria spectabilis; as gramíneas Pennisetum glaucum (milheto), Sorghum bicolor (sorgo-forrageiro), Panicum maximum e Urochloa brizantha; além de um consórcio entre milho (Zea mays) e U. brizantha (sistema Santa Fé). Os experimentos seguiram o delineamento em faixas, com quatro repetições. A incidência da murcha-de-fusário foi maior no sistema plantio direto. As maiores incidências da doença corresponderam ao menor rendimento do feijão-comum em 2003 e 2004. Cultivos de verão prévios com U. brizantha, U. brizantha consorciada com milho, e milheto apresentaram as menores incidências da doença. Portanto, a escolha desses cultivos prévios deve ser considerada para o manejo da murcha-de-fusário, em cultivos irrigados de feijão-comum no Cerrado brasileiro.Termos para indexação: Fusarium oxysporum, Phaseolus vulgaris, integração lavoura-pecuária, rotação de culturas, plantio direto, patógenos habitantes do solo.