Effects of loose smut on Digitaria sanguinalis population depending on seedlingemergence period

摘要

Fungal plant pathogens can impact on host fitness. The effects of the systemic smut fungus Ustilagosyntherismae on the morphology, growth and fecundity of the Digitaria sanguinalis population at the endof its annual cycle were assessed during two consecutive years considering the emergence time of hostindividuals (cohorts). U. syntherismae had an important impact on the D. sanguinalis population, becausemost of the infected plants (97.2%) were totally castrated. Smut fungus significantly reduced above-ground biomass (61.5%), height (23.7%) and the number of basal shoots (15.5%) and increased the numberof nodes (12.9%), ramifications (52.4%) and inflorescences (16.7%) of the individuals. In view of the factthat the cohort was a significant source of variation in the percentage of diseased plants in the secondyear of study, our results do not support the idea that smutted plants appear earlier in the season,because the time of seedling emergence was not a factor that constrained the disease incidence.