Submitted to: World Journal of Microbiology and Biotechnology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/11/2009
Publication Date: 5/1/2010
Publication URL: handle.net/10113/43932
Citation: Boyette, C.D., Bowling, A.J., Vaughn, K.C., Hoagland, R.E., Stetina, K.C. 2010. Induction of Infection in Sesbania exaltata by Colletotrichum gloeosporioides f. sp. aeschynomene Formulated in an Invert Emulsion. World Journal of Microbiology and Biotechnology. 26:951-956. Interpretive Summary: A process was developed to extend the host range of the commercial bioherbicidal fungus, Colletotrichum gloeosporioides f. sp. aeschynomene (CGA), using a formulation-based approach. Aqueous CGA formulations effectively control northern jointvetch, a serious rice weed, but do not affect other important weeds such as hemp sesbania. In greenhouse tests, we found that hemp sesbania plants were infected and killed by CGA fungal spores formulated in an invert emulsion. Ultrastructural analysis revealed that hemp sesbania tissues were severely disrupted by fungal mycelium. CGA, re-isolated from infected hemp sesbania tissues, infected and killed northern jointvetch, thus confirming disease identification. Results indicate that CGA can control hemp sesbania if formulated in an invert emulsion, thus improving its bioherbicidal marketing potential.
Technical Abstract: In greenhouse experiments, an experimental invert emulsion (MSG 8.25) was tested as an adjuvant with spores of the mycoherbicidal fungus Colletotrichum gloeosporioides f. sp. aeschynomene, a highly virulent pathogen of the leguminous weed Aeschynomene virginica (northern jointvetch), but non-pathogenic against another leguminous weed, Sesbania exaltata (hemp sesbania). A 1:1 (v/v) fungus/invert tank mixture resulted in 100% infection and mortality of inoculated hemp sesbania seedlings over a 21 day period. Microscopic examinations revealed that the fungus proliferated within cells of hemp sesbania, producing anthracnose lesions containing acervuli on infected stems. The fungus was reisolated and infected and killed northern jointvetch seedlings, thus fulfilling Koch’s postulates for disease identification. These results suggest that this invert emulsions alters the host range of C. gloeosporioides f. sp. aeschynomene, thus improving the bioherbicidal potential of this pathogen for control of northern jointvetch, a serious weed pest in the southeastern US.