Two new species of Piricularia collected in the Amazon region

Abstract

Descriptions of two species of Piricularia have been proposed as new. These species where collected in the Amazon Region, in forested areas belonging to the Instituto de Pesquisas e Experimentação Agropecuárias do Norte. The genus Piricuaria Sacc. included in the hyphomycetes group has very few known species totaling five or six. None of them has developed structures of the perfect stages. The specific name adopted were Piricularia guarumeicolae, parasitic on leaves of Ischnosiphon simplex Hub. (guarumãmirim) and Piricularia lourinae, that causes leaf spots on Aniba burchellii Kostern (louro). Experimental inoculation tests verified that the species Ischnosiphon obliquus (Rudge) Koern (guarumã-açú) is susceptible to leaf blight caused by Piricularia guarumeicolae. However, in the natural state symptoms of the disease have not been observed in plants of “guarumã-açú". It is probable that morphological factors or those related to the constitution of the tissues impede the development of the infection. Pure cultures of the fungi in laboratory artificial media were obtained. The pathogenicity of the eumycete Piricularia guarumeicolae was confirmed through inoculation tests on pot-seedlings. The leaves were inoculated with spore suspensions obtained from media consisting of soft green stem and leaves of the host, cut into small pieces, to which was added agar dissolved to 2%. Up to the present time these imperfect fungi have not been the cause of diseases of economic importance. They could be important pathogens to the productivity of other cultivated species belonging to the families of the host plants, as the arrow-root and the avocado. They are important in the systematics of eumycetes. The could be of interest to the ecological study of an area.