Experimentos en el control de Pellicularia del café y ciertas diferencias en Pelicularias de cinco huéspedes

Abstract

Coffea arabica is severely attacked by the fungus Pellicularia koleroga, known to well in many coffee countries. It is especially important in Turrialba, Costa Rica where it was studied. This Pellicularia from coffee was compared with others from cacao, hibiscus, beans, and crotonal. The latter two were found to be of one species, while those from cacao and hibiscus were specifically different from each other, and were not the same as the coffee fungus or that from the legumes. It is of special interest that the Pellicularia from hibiscus, was found as parasitic on a coffee tree cricket. The Pellicularia produced oxalic acid crystals in culture and in the tissues of diseased leaves. Laboratory techniques were given major attention towards studies that resulted in fuller understanding of all these fungi in culture. Microscopic and cultural examinations, and cross inoculations combined with physiological studies, all confirmed the fact that there were four specifically different Pelliculariae. Evaluations under careful laboratory conditions, were made with cultures of P. koleroga of coffee, using numerous fungicides and stickers. Of special note were the following: in cultures, the sticker Triton appeared to have appreciable inhibiting effect. Copper was also an inhibitor in fungicides. Both Orthocide and Fermate were strong as inhibitors in vitro. When used in glass moist chambers, there was no infection of excised leaves that had been treated with Orthocide or Fermate. Under these special conditions, there was some infection of excised leaves that had been sprayed with Bordeaux mixture, Crag and Copper A but there was most infection on untreated leaves. In moist chambers, the fungicide Captan caused severe phytotoxicity. One reason's work in the field indicated that the fungicides Tuzet, lead arsenate, Triotrofotol, and Perexon gave best control of coffee Koleroga. Orthocide and Fermate did not give as good results as the laboratory tests promised, but the trees thus treated had less infection than unsprayed trees. Tuzet was a good inhibitor of koleroga in the field but was at a certain disadvantage and caused severe phytotoxic effects on the trees. Thus, it cannot be recommended, at least with the formulation used here.