Epidemiology and management of coffee (Coffea arabica L.) diseases under organic farming. / Epidemiologia e manejo de doenÃas do cafeeiro (Coffea arabica L.) sob cultivo orgÃnico

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The present work aimed to study coffee diseases on organic crop system. For that, rust and black eye spot disease progress on organic and conventional crop systems were compared. The effect of nutrient sources in the disease management was evaluated and, finally, the effect of plant extracts in the protection of coffees in the organic system was tested. The experiments used two neighboring fields in Santo AntÃnio do Amparo city, MG, between november 2003 and november 2005. Crops are under similar weather, soil and relief conditions and are made up of ten-year-old coffee cv. Acaià MG-474-19. In two consecutive organic production cycles rust was more intense than brown eye spot. Comparatively, the progress of rust in the organic system was higher than the observed in the conventional system while brown eye spot was similar in both agricultural years 2003/2004, but it enhanced in the conventional one in the years 2004/2005. Organic coffee yield in 2005 decreased 34% compared to harvest 2004 (high number of berries). In the conventional system, this reduction was up to 64%. This suggests a tendency of lower effect of diseases on the following harvest for the organic system, compared to the conventional one. In the monitored period of the present study, the nutritional status of coffees in the organic system was better balanced compared to the conventional one, which showed lower foliar content of calcium and magnesium in the fruit filling and ripening phases. In the organic system, it was observed that the percent rust and brown eye spot can be influenced by the used source of nutrient and this has been attributed to nutritional imbalance observed as a function of the high potassium contents and low foliar calcium and magnesium mainly in the fruit ripening phase. Coffee peel used as sole source of nutrient produced a higher rust and brown eye spot intensity, differing from other treatments such as swine waste combined with coffee fruit peel, castor bean presscake associated with crotalaria, bovine manure associated with crotalaria, castor bean presscake associated with coffee fruit peel and the control considered as the regular fertilization used in the farm that combined organic compost, castor bean presscake, swine waste and crotalaria. The use of castor bean presscake associated with coffee peel and swine waste associated with coffee peel reduced the area under the rust and brown eye spot progress curves, statistically similar to the control, from which intensities of rust and brown eye spot were lower. This performance was related to the higher availability of foliar calcium in plants because of those treatments. In the second harvest (low number of berries), the treatments affected coffee productivity. The lowest ones were obtained in coffees fertilized only with coffee peel (9.0 sacks/ha) and in the treatment with bovine manure associated with crotalaria (16.6 sacks/ha). In comparisons, the higher yield was verified in the control (36.6 sacks/ha). The verified productivities in the treatments swine waste combined to coffee fruit peel (28.1 sacks/ha), castor bean presscake combined with coffee fruit peel (27.8 sacks/ha) and castor bean presscake combined with crotalaria (26.6 sacks/ha) were not statistically different from the control in 2005. In order to maintain the balance of nutrients during the coffee fruiting, as well as to reduce the susceptibility to rust and brown eye spot, the use of two sources of nutrient, such as coffee fruit peel combined to castor bean presscake or swine waste, constantly had an effect similar to the observed in the control with four different sources. Promising results were obtained with plant extracts in inducing protection against rust, brown eye spot and Phoma spot in organic coffee. Aqueous extracts of coffee fruit peel and coffee leaves infected with rust reduced the incidence of rust, brown eye spot and phoma spot comparatively to the percent disease observed in the control, sprayed with water. The extract of coffee fruit peel reduced the incidence of brown eye spot in 34% compared to ViÃa-cafÃ, considered the positive control. The aqueous extract of lobeira broom reduced the severity of rust in 23.6% and 19% compared to the positive control. The best result was obtained by extract of rust infected coffee leaf once it reduced Phoma incidence in 40% compared to the control with ViÃa-cafÃ. A commercial extract of citric biomass (EcolifeÂ) had a performance intermediate between the best treatments and the positive control. Accumulation of lignin verified in the treatments sprayed with plant extracts of coffee tissues and lobeira broom confirmed the promising performance of these

ASSUNTO(S)

hemileia vastatrix phoma tarda phoma tarda resistance cercospora coffeicola nutrition nutriÃÃo cafà cercospora coffeicola induÃÃo de resistÃncia coffee trees fitopatologia hemileia vastatrix

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