Incidence of Tar Spot Disease of Corn in Puerto Rico

Abstract

Tar spot of corn was observed for the first time during the last decade in Puerto Rico at the Corozal Substation and then on the farm at Cidra infecting an inbred line of corn introduced recently from Jamaica. Studies on the morphology of ascospores and perithecia revealed that the tar spot fungus resembles Phyllachora maydis Maubl. Results of pathogenicity trials indicate that the fungus can infect only corn seedlings approaching maturity.