Escala diagramática para avaliação de mofo cinzento (Amphobotrys ricini) da mamoneira (Ricinus communis L.)

Abstract

The aim of the present study was to develop a diagrammatic scale to assess gray mold caused by Amphobotrys ricini in castor bean (Ricinus communis L.). The experiment included 59 clusters, which were disinfected in solution of sodium hypochlorite to 2% for 30 seconds and distilled water and sterilized. Then, they were packed in moistened foam trays which received 5mm mycelial discs, and were kept in a climatic chamber at 25 o C and 80%. RH. A mamoneira (Ricinus communis L.) pertence a família Euphorbiaceae e gênero monotípico, ou seja, é a única espécie do gênero Ricinus. É uma espécie preferencialmente autógama, mas pode apresentar alta taxa de cruzamentos, podendo chegar a 40% de acordo com Beltrão et al. (3). Dos produtos obtidos, o óleo é o mais explorado comercialmente. Devido à alta capacidade de reações químicas dadas pelo ácido graxo ricinoléico, o óleo tem larga aplicação na fabricação de tintas, vernizes, detergentes, inseticidas, resinas de plástico, lubrificantes, fungicidas e bactericidas, próteses humanas para coluna vertebral, crânio, dentes e mamas (6 ,8).Embora seja uma planta com grande capacidade de adaptação às mais diferentes regiões do mundo, a mamoneira está sujeita a doenças causadas por diversos microorganismos, os quais causam grandes prejuízos econômicos (7,17).Entre essas doenças, pode-se destacar o mofo-cinzento, causado pelo fungo Amphobotrys ricini (Buchw.) Hennebert (sin. Botrytis ricini N.F. Buchw.) (Teleomórfico Botryotinia ricini (G.H. Godfrey) Whetzel, sendo a principal doença da cultura da mamoneira. O patógeno encontra-se disseminado em todas as áreas de cultivo dentro do território brasileiro, ocorrendo agressivamente sempre que as condições climáticas são favoráveis. Essas condições são temperatura ao redor de 25 o C e Umidade Relativa do ar acima de 75%. A doença causa grandes prejuízos à produção, afetando inflorescências, cachos e frutos, reduzindo assim a produção de óleo pela diminuição dos frutos colhidos e ,sua qualidade segundo Lima et al. (13).A principal forma de disseminação do patógeno é por esporos carreados pelo vento e por sementes, de acordo com Neergaard (15). Porém alguns insetos, atraídos pela grande exsudação de néctar nas flores, também desempenham papel na disseminação de A. ricini (11, 14).Os primeiros sintomas são pequenas manchas de tonalidade

Evaluation of Pseudomonas fluorescens Strains, Fungicides and Non-conventional Chemicals Against Botyrotinia ricini Causing Grey Mold Disease in Castor

“…Simiarly, Bezerra (2007) also reported that carbendazim was effective against grey rot under controlled conditions. Chagas (2009) reported that carbendazim, tebuconazole, iprodione and procymidone were highly effective against grey rot under in vitro and in vivo conditions. Fungicides such as armure, thiram, edifenphos and carbendizam and their mixtures were proved effective against B. ricini mycelia growth rate and spore germination under in vitro conditions.…”

“…Though there are several studies on use of other biological control agents like Trichoderma spp. to control gray mold in castor(Bhattiprolu and Bhattiprolu, 2006;Chagas, 2009; Raoof et al, 2003; Tirupathi et al, 2006), there are limited studies on use of P. fluorescens.Raoof et al (2003) reported the use of both P. fluoresens and T. viride to manage B. ricini, however, single isolates were evaluated in the study compared to the forty isolates used in this study.…”

Gray Mold of Castor: A Review

“…Nonetheless, the simple fact that such a diagrammatic scale is now available is a huge advance towards more reliable disease assessment and the possibility of comparing assays conducted by different researchers in different localities. Chagas et al (2010) also developed a diagrammatic scale, with six levels, to assess the disease severity of gray mold on castor, but similar to the scale developed by Sussel et al (2009), this scale was also developed based on long conical, full developed, racemes, and thus, will face the same problem mentioned above. Fig.…”

“…Preliminary studies under controlled conditions have shown that carbendazim and azoxystrobin are effective against the gray mold pathogen (Bezerra, 2007). According to Chagas (2009), however, azoxystrobin was ineffective against B. ricini, while carbendazin and several others fungicides, including tebuconazole, iprodione and procymidone, were highly effective.…”

“…If we consider the fact that the genera Botrytis and Amphobotrys are biologically similar and, probably, phylogenetically related, we could expect that the use of such biological control agents could be applied as an effective strategy in the pathosystem B. ricini x R. communis. Actually, there are some studies conducted with Trichoderma and Clonostachys rosea for the control of gray mold of castor and promising results have been obtained (Bhattiprolu & Bhattiprolu, 2006;Chagas, 2009;Demant et al, 2006;Raoof et al, 2003;Tirupathi et al, 2006). However, it is clear that, although promising, these results are still experimental and much work needs to be done before permanent recommendations regarding the use of biological control agents can be secured for gray mold management.…”