Transmissibilidade e efeito do tratamento de sementes de cafeeiros com mancha manteigosa (C. gloeosporioides)

Abstract

RESUMONeste trabalho, os objetivos foram avaliar a transmissibilidade de C. gloeosporioides mancha manteigosa (MM) em sementes e estudar o efeito do tratamento por fungicidas no controle do referido patógeno. Colheram-se frutos cerejas em plantas doentes e sadias, procedeu-se o despolpamento manual secando as sementes à sombra, retirou-se o endocarpo e, em seguida, realizaram-se os devidos tratamentos (fungicida) semeando-as em areia esterilizada. Avaliaram-se os sintomas de necrose e morte das plântulas e a incidência de C. gloeosporioides, por meio do teste de incubação em substrato de papel (blotter test), em sementes de cafeeiro tratadas e não tratadas com mistura comercial de benzimidazol+dimetilditiocarbamato (dose i.a. de 45 g+105 g/100 kg sementes). Com o desenvolvimento das plântulas, observaram-se em sementes de plantas com MM , altos índices de morte de plântulas, tendo apenas 5,2% de sobrevivência, porém, com a abertura dos primeiros folíolos observaram-se, nestas plântulas, sintomas típicos da doença, com posterior morte das mesmas, enquanto que, a partir de sementes sadias, as plântulas apresentam-se vigorosas e em pleno crescimento. Já, com o uso do tratamento fungicida, observou-se efeito significativo, principalmente em sementes de plantas doentes (MM), nas quais verificou-se uma menor área abaixo da curva de progresso da doença e, consequentemente, menor incidência e severidade da doença. Pelo bloter test, em sementes tratadas, não houve crescimento de nenhum agente fúngico tanto para sementes de plantas com MM como para sementes de plantas sadias. Em sementes não tratadas, observou-se incidência de C. gloeosporioides em 29,8% nas sementes de plantas com MM e 1,2% de incidência em sementes de plantas sadias. Com base nestes resultados, fica evidenciado que neste patossistema, mancha manteigosa -cafeeiro, a principal via de transmissão de C. gloeosporioides é a semente.Termos para indexação: Sementes, fungicidas, Colletotrichum gloeosporioides e Coffea arabica. ABSTRACTThe objectives in this study were: (i) the assessment of the transmission of blister spot(C. gloeosporioides) from seed to plant, and (ii) an observation study on the effect of seed treatment with fungicides used in the control of that disease. Natural transmission of the fungus was studied in seeds collected from both healthy and diseased 'Catucaí' coffee trees. The endocarp of the seeds was removed, and the seeds were sowed in sterilized sand substrate. The symptoms and the death process of hypocotyls were evaluated. Additionally, the incidence of blister spot (C. gloeosporioides) was assessed through blotter test in both fungicide treated and untreated seeds. A large number of hypocotyl deaths in seeds obtained from blister spot trees were observed, whereas seeds collected from healthy trees produced healthy seedlings. A total of 5.2% of the seedlings from blister spot trees were apparently healthy. But after the completion of the development of the first pair of leaves, blister spot symptoms were observed. When treated with fu...

Effect of chemical treatment on the physiological and sanitary quality of stored coffee seeds

“…However, an even greater reduction in incidence of the pathogen occurs in treated seeds after 3 months of storage, showing the effectiveness of the product in control of the pathogen (Figure 7.4). Ferreira et al (2010) also observed a reduction in the incidence of Phoma spp. in coffee seeds after the chemical treatment with the active ingredients benzimidazole + dimethyldithiocarbamate.…”

“…However, for the coffee crop, there is no recommendation of this product or other registration in the Brazilian Ministry of Agriculture (Ministério da Agricultura, Pecuária e Abastecimento -MAPA) for seed treatment. In addition, few studies with coffee have been performed using chemical products registered in MAPA for other crops, such as in the study of Ferreira et al (2010) using a product of active ingredients Carbendazim (150 g/L) and Thiram (350 g/L) to assess the transmissibility of the fungus Colletotrichum gloeosporioides and the effect of treatment of coffee seeds in the presence of this disease.…”

Chemical and biological treatments of castor bean seeds: effects on germination, emergence and associated microorganisms

“…The seeds, distributed in 42 gerbox type boxes, with 20 seeds per box, were incubated at 24 ºC and a 12 hour photoperiod, using the technique similar to Ferreira et al (2010). Evaluations were made on the 7th day after incubation and microorganism structure was observed with a stereoscopic and optical microscope.…”