EFECTO DE Fusarium circinatum EN LA GERMINACIÓN Y CRECIMIENTO DE PLÁNTULAS DE Pinus greggii EN TRES SUSTRATOS.

The drying disease affects plants grown in forest nurseries during the pre-emergence and post-emergence stages, constricting the stem and causing root rot. The objectives of this study were to identify the morphological and molecular characteristics of the Fusarium species that affects the nursery located in Atlangatepec, Tlaxcala, which causes the drying disease and root rot of Pinus greggii Engelm., to evaluate its effect in the germination of seeds in three substrates, and to analyse the incidence and pathogenicity of developing seedlings. The Fusarium fungus was isolated from diseased seedlings, it was purified, and, based on its morphology and molecular structure, as identified as F. circinatum Nirenberg & O'Donnell. The substrates were: peat moss, perlite, and vermiculite (S1); sawdust, bark, and peat moss (S2); and bark, sawdust, and peat moss (S3); they were evaluated in 60:20:20 ratios. The experiment had a completely randomized design, with six treatments and four repetitions per each one. The statistical analysis of the germination percentage was executed with ANOVA and the means comparison was carried out using the Duncan test (p≤0.05). The fungus produced a significant reduction in the germination of P. greggii's seeds. Disease incidence was lower in S2, during the first two months, and its post-emergence pathogenicity was proved by the induction of symptoms and reisolations of F. circinatum. [ABSTRACT FROM AUTHOR]