Corynespora cassiicola f. sp. schinii, a Potential Biocontrol Agent for the Weed Schinus terebinthifolius in the United States

Abstract

Schinus terebinthifolius (Anacardiaceae), Brazilian peppertree (BP), is a major environmental weed in many tropical and subtropical areas of the globe, including Florida, Hawai'i, and Australia. This plant has been the target of a classical biocontrol project in the United States involving pathogens collected in Brazil for several years. A fungus was found in the Brazilian state of Espírito Santo causing leaf spots and severe foliage blight on BP. Examination of the morphology and internal transcribed spacer sequence analysis confirmed that the fungus is a strain of Corynespora cassiicola. Preliminary host-range tests involving 24 species, including 11 species in the family Anacardiaceae, were conducted with the fungus, and specificity toward BP was confirmed. Plants of Brazilian pepper tree from populations in Florida and Hawai'i included in the tests became severely diseased. Therefore, the recognition of a new forma specialis—Corynespora cassiicola f. sp. schinii—is proposed. The specificity of this forma specialis and the severity of the disease it caused in the field and under controlled conditions indicate that it has the potential for use as a biocontrol agent for BP in areas where it is an exotic invasive species.