Controle alternativo de Colletotrichum acutatum agente causal da queda prematura dos frutos cítricos
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Data
2009-12-01
Autores
Kupper, Katia Cristina
Bellotte, José Antonio Miranda
Goes, Antonio de [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira de Fruticultura
Resumo
A queda prematura dos frutos cítricos (QPFC), causada por Colletotrichum acutatum, dados os grandes prejuízos que têm causado aos produtores, constitui-se numa doença de grande importância econômica. O controle da doença é feito predominantemente mediante uso de fungicidas, que eleva o custo de produção e afeta negativamente o meio ambiente. Diante disso, este trabalho teve por objetivo buscar um método alternativo de controle da QPFC, mediante o uso de agentes de biocontrole ou de biofertilizantes. Diferentes concentrações de biofertilizantes (originários de duas fontes distintas e denominados de Bio1 e Bio 2); três isolados de Bacillus subtilis (ACB-69; 72 e 77) e três isolados de Trichoderma spp. (ACB-14; 37 e 39) foram testados, isoladamente ou em combinação, sob condições de laboratório, quanto à capacidade inibitória da germinação de conídios de C. acutatum. Estudaram-se, ainda, a produção de metabólitos termoestáveis por B. subtilis e o efeito sobre a germinação do patógeno. Quinze isolados de B. subtilis foram testados quanto à capacidade de prevenir a infecção por C. acutatum em flores destacadas de lima- ácida 'Tahiti' e, no campo, foram instalados dois experimentos, visando a testar ACBs e biofertilizantes no controle da doença. Verificou-se que o isolado ACB-72 (B. subtilis) e ACB-37 (T. pseudokoningii) foram os que mais inibiram a germinação do patógeno. Quanto à produção de metabólitos termoestáveis, ACB-69 e 77 foram os mais eficientes em produzir substâncias antifúngicas, e em quantidades suficientes para inibirem a germinação do patógeno. A mistura dos quatro isolados de Bacillus (ACBs: 69; 72; 77 e AP3) foi o que apresentou maior porcentagem de inibição (73%). Os biofertilizantes (Bio1 e Bio2), em concentrações acima de 10% e, quando em associação com isolados de Trichoderma spp., promoveram maiores inibições na germinação de C. acutatum. em testes com flores destacadas, verificou-se que, onde foram aplicados os ACBs 69; 76; 74 e 77, as porcentagens de pétalas sem sintomas de infecção por C. acutatum foram de 83; 92; 92 e 97%, respectivamente. Mediante avaliações a campo, verificou-se a potencialidade de B. subtilis e de biofertilizantes em controlar a doença.
Postbloom Fruit Drop of Citrus (PDF), caused by Colletotrichum acutatum, has caused losses to citrus producers and therefore it is economically very important. This disease is generally controlled by fungicide sprayings, which increase the production cost, and affects the environment. Thus, this work aimed at developing an alternative control method through the use of biocontrol agents, or biofertilizers. Different concentrations of biofertilizers (from two distinct sources and named Bio1 and Bio2), three strains of Bacillus subitlis (BCA-69, 72 and 77) and three isolates of Trichoderma spp. (BCA-14, 37 and 39) were tested, in vitro, alone or in combination, for the inhibitory capacity of conidia germination of C. acutatum. It was studied the production of thermo-stable metabolites by B. subtilis and their effect on the germination of C. acutatum conidia. Under in vivo conditions, 15 isolates of B. subtilis were tested for the ability to prevent C. acutatum infection on 'Tahiti' lime detached flowers and in the field, where two experiments were installed, for testing the BCA and biofertilizers in the control of the disease. It was found that the isolate BCA-72 (B. subtilis) and BCA-37 (T. pseudokoningii) were the most efficient in inhibiting conidia germination. BCA69 and BCA-77 were the most effective in producing anti-fungal substances, and in quantities sufficient to inhibit the germination of C. acutatum. The mixture of four strains of Bacillus (BCA: 69, 72, 77 and AP3) presented the highest percentage of inhibition (73%). Regarding the use of biofertilizers (Bio1 and Bio2), it was observed that concentrations above 10% of the product, when combined with the strains of Trichoderma spp. decreased the pathogen germination. The experiments with detached flowers showed that the flowers where the BCA: 69, 76, 74 and 77 were applied presented 83, 92, 92 and 97% respectively, of the petals without symptoms of infection by C. acutatum. Field tests showed the potential of B. subtilis and biofertilizers in controlling the disease.
Postbloom Fruit Drop of Citrus (PDF), caused by Colletotrichum acutatum, has caused losses to citrus producers and therefore it is economically very important. This disease is generally controlled by fungicide sprayings, which increase the production cost, and affects the environment. Thus, this work aimed at developing an alternative control method through the use of biocontrol agents, or biofertilizers. Different concentrations of biofertilizers (from two distinct sources and named Bio1 and Bio2), three strains of Bacillus subitlis (BCA-69, 72 and 77) and three isolates of Trichoderma spp. (BCA-14, 37 and 39) were tested, in vitro, alone or in combination, for the inhibitory capacity of conidia germination of C. acutatum. It was studied the production of thermo-stable metabolites by B. subtilis and their effect on the germination of C. acutatum conidia. Under in vivo conditions, 15 isolates of B. subtilis were tested for the ability to prevent C. acutatum infection on 'Tahiti' lime detached flowers and in the field, where two experiments were installed, for testing the BCA and biofertilizers in the control of the disease. It was found that the isolate BCA-72 (B. subtilis) and BCA-37 (T. pseudokoningii) were the most efficient in inhibiting conidia germination. BCA69 and BCA-77 were the most effective in producing anti-fungal substances, and in quantities sufficient to inhibit the germination of C. acutatum. The mixture of four strains of Bacillus (BCA: 69, 72, 77 and AP3) presented the highest percentage of inhibition (73%). Regarding the use of biofertilizers (Bio1 and Bio2), it was observed that concentrations above 10% of the product, when combined with the strains of Trichoderma spp. decreased the pathogen germination. The experiments with detached flowers showed that the flowers where the BCA: 69, 76, 74 and 77 were applied presented 83, 92, 92 and 97% respectively, of the petals without symptoms of infection by C. acutatum. Field tests showed the potential of B. subtilis and biofertilizers in controlling the disease.
Descrição
Palavras-chave
Bacillus subtilis, Trichoderma spp, biofertilizante, Bacillus subtilis, Trichoderma spp, Biofertilizer
Como citar
Revista Brasileira de Fruticultura. Sociedade Brasileira de Fruticultura, v. 31, n. 4, p. 1004-1015, 2009.