Muerte descendente causada por Colletotrichum en las plantas de café en el almácigo y su combate por medio de aspersiones en Turrialba, Costa Rica

Abstract

A study was made in coffee nursery trees of a serious leaf spotting, defoliation, and dying-back of terminal and lateral branches. Isolations from leaves, flowers, fruits, branches, stems and roots yielded high percents of Colletotrichum coffeanum Noack. Inoculation experiments proved the pathogenicity of the organism and indicated strain differences among the isolates, greater infections were obtained in plants under little shade, in younger leaves, and at very high humidities.

Of several fungicides that were tried, Fermate gave the best control of the disease. Bordeaux Mixture failed to control it and caused some injury in the coffee. Disease incidence was much greater in the no shaded plots than in those with 50% shade.

Weekly and biweekly spray applications were compared in a large test run for 12 months, comparing Parzate, Zarlate, Fermate, Copper A, Dithane and Tribasic Copper. For both spray schedules Fermate gave highly significant improvement over the controls and was generally superior to the other treatments, but differences between weekly and biweekly applications of Fermate were not statistically significant. Spraying with Fermate reduced very markedly the loss of the branches produced during the year. Zarlate and Dithane in some analyses, gave highly significant improvement over the untreated plots. Copper sprays applied weekly considerably injured the plants; increased infection appeared with Parzate treatments.