Coffee Rust Epidemic in Brazil.

Coffee is one of the most important crops in Brazil, with historical relevance, mainly for Minas Gerais and São Paulo States, the two major producers. The most injurious disease is coffee rust (CR)(Hemileia vastatrix), affecting Brazilian production every year. A 16-year analysis of the CR epidemic was carried out to clarify AUDPC, the epidemic start and the months with the highest progress, using leaves incidence data. Two fields were chosen for each growing season, both on Procafé Foundation farm, Varginha-MG, with coffee trees with susceptible cultivar. These fields of 4000 trees ha^-1 were differentiated by high (HL) and low (LL) fruit load, which is an important factor influencing CR development. In both fruit loads, the epidemic begins in November, whereby HL has a monthly increase incidence with a peak in July and CR decreasing July only in four of the 16 years. On the other hand, LL fields show almost flat progress, maintaining incidence between 15 and 25% until May, with higher than this in eight of 16 years in June, the characteristic epidemic end. The AUDPC average in HL and LL is 13320 and 5447, respectively. The months with maximum incidence progress in HL are from March to April, with an average increase of 18%, while in the other months, this average is 11%. In LL, this progress occurred in the same period, but with an increase of 6%, while the average is 4%. Consequently, in HL years growers need to have special attention to CR management, keeping it under control avoiding losses while in LL years, CR is not usually harmful. As next step to this study, we intend to forecast when a growing season will threaten more coffee fields, helping growers with an early-season management system, containing a probable recommended quantity of sprays, besides a sprays-date program.