Controle alternativo de Colletotrichum acutatum agente causal da queda prematura dos frutos cítricos

Abstract

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. ALTERNATIVE CONTROL OF Colletotrichum acutatum, CAUSAL AGENT OF POSTBLOOM FRUIT DROP OF CITRUSABSTRACT -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 fl owers and in the fi eld, 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 effi cient in inhibiting conidia germination. BCA-69 and BCA-77 were the most effective in producing anti-fungal substances, and in quantities suffi cient 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 fl owers showed that the fl owers 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.

Application of microorganisms, alone or in combination, to control postbloom fruit drop in citrus

“…The levels of control of postbloom fruit drop by isolate ACB-69 in the experiments reported here were similar to what was obtained in other trials with the same isolate (Kupper et al, 2003(Kupper et al, , 2009(Kupper et al, , 2012. However, this was the first attempt of mixing this isolate with other biocontrol agents for control of postbloom fruit drop.…”

Physiological and sanitary quality of maize seeds treated with biological control agents

“…Thus, one of the alternatives to avoid the excessive use of fungicides is plant disease control with substances that have lower environmental impact (Camargo, 2007), such as biological control agents (Mertz et al, 2009). Among biological control agents, the antagonistic bacteria Bacillus subtilis, Pseudomonas cepacia, P. fluorescens (Weller, 2007, Trotel-Aziz et al, 2008, Chen et al, 2009) and the fungus Trichoderma harzianum (Kupper et al Al., 2009) are highlighted.…”

Tetraphenylphosphonium and Tris (1.10-PHENANTHROLINE) Iron(ii) Salts of Anionic Complexes of Dibutyltin(iv) With Dithiocarbimates: Synthesis, Characterization and Antifungal Activity

“…A podridão amarga, doença de maior importância na cultura da macieira, também é resultado da infecção por C. acutatum. [9][10][11] Tendo em vista essas considerações, este trabalho descreve a síntese de seis novos sais com ânions complexos de dibutilestanho(IV) com ditiocarbimatos e os cátions: tetrafenilfôsfonio e tris(1,10-fenantrolina)ferro(II), de fórmulas gerais: (Ph 4 P) 2 12 Os sais N-R-sulfonilditiocarbimatos de potássio di-hidratados foram preparados em dimetilformamida utilizando a sulfonamida, dissulfeto de carbono e hidróxido de potássio, de acordo com metodologia descrita para a síntese de compostos semelhantes. A obtenção desses compostos foi confirmada pela comparação dos espectros no IV com os dados publicados.…”