SWISS NEEDLE CAST (Phaeocryptopus gaeumannii (Rhode) Petrak) IN Pseudotsuga menziesii var. glauca (Beissn.) Mayr

Abstract

There are native populations of Phaeocryptopus gaeumannii in Mexico as colonizing species of Pseudotsuga menziesii var. glauca. This fungus is the cause of the Swiss Needle Cast, a disease that provokes premature defoliation and a reduction in growth. The aims of the this paper were to identify and describe molecularly this pathogen in different geographical areas and to clear up some details of its biological cycle. Therefore, P. menziesii var. glauca leaves with ripe pseudothecia were collected in eight states of the country and a sample from Oregon (United States of America) was taken; they were isolated in 1.5 % water-agar (WA) and were kept in a potatoe – dextrose - agar (PDA) cultivation media for 60 days. To identify them, morphological features were considered as well as the results of the nuclear gene amplification, through the ITS - PCR which showed 99 to 100 % of identity. Growth was radial, olive green to grey color, without formation of reproductie structures. P. gaeumannii is found in the natural forests of Sierra Madre Occidental, Sierra Madre Oriental and Sierra Madre del Sur, as in several Christmas tree plantations at central Mexico. Ascospores became ripe in March and are visible in the atmosphere; the main dispersion occurrs from June and July; in regard to the climate and the locality; in September and October they diminish their amount.