Progresso da cercosporiose (Cercospora coffeicola Berkeley & Cooke) em cafeeiros sob cultivos orgânico e convencional

The progress of brown eye spot in coffee trees in both organic and conventional crop systems was evaluated in two neighboring fields, in Santo Antonio do Amparo city, MG, between nov./2003 and nov./2005. The fields are under similar weather, soil and relief conditions and made up of ten-year-old coffee trees cv. Acaia MG-474-19. The incidence of brown eye spot was significantly higher in conventional system, whose average from two years demonstrated the area under the disease progress curve (3.905) higher than organic system (2.529). That was also demonstrated by the higher incidence on leaves (maximum 28% in 2004 and 29% in 2005) on conventional than on organic system (9% and 12%, respectively). The incidence on fruits was 18.2% in 2004 and 22% in 2005, while on organic system it was 11.5% and 15%, respectively. This higher susceptibility to disease on coffee trees in conventional system coincided with lower foliar content of calcium and magnesium for the fruit filling and fruit ripening stages compared with to the organic system. That was a consequence of higher production of the conventional system that resulted in yield 47.8% higher than organic one in 2004 (high number of berries). In 2005, the yield was similar in both crop systems but it was verified that the conventional production in 2005 was 64% lower than in 2004 whereas in the organic system from the difference in yield was 34%. This suggested for a tendency of lower effect of the disease in the following coffee harvest of the organic system compared to the conventional one.