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

Abstract

The 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 fungicides (benzimidazol + dimethyldithiocarbamate), seeds from blister spot and healthy trees were free of fungi. Seeds collected from blister spot trees presented an incidence of 29.8% C. gloeosporioides , whereas seeds collected from healthy trees had an incidence of 1.2%. Therefore, based on the results of this study, it was clear that seeds were the principle means of transmission of blister spot in coffee.