ARS | Publication request: Hemp Sesbania (Sesbania exaltata) control in rice (Oryza sativa) with the bioherbicidal fungus Colletotrichum gloeosporioides f. sp. aeschynomene formulated in an invert emulsion

Submitted to: Biocontrol Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 16, 2011
Publication Date: December 1, 2012
Citation: Boyette, C.D., Gealy, D.R., Hoagland, R.E., Vaughn, K.C., Bowling, A.J. 2012. Hemp Sesbania (Sesbania exaltata) control in rice (Oryza sativa) with the bioherbicidal fungus Colletotrichum gloeosporioides f. sp. aeschynomene formulated in an invert emulsion. Biocontrol Science and Technology. 21 (12):1399-1407.

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 by CGA formulated in an invert emulsion, with 100% mortality occurring 21 days after treatment. In replicated field tests of the fungus/invert formulation conducted in Stuttgart, AR, and Stoneville, MS, hemp sesbania was controlled 85% and 90%, respectively. These results suggest that this invert emulsion expands the host range of C. gloeosporioides f. sp. aeschynomene, with a concomitant improvement of the bioherbicidal potential of this pathogen. Results indicate that CGA can control hemp sesbania if formulated in an invert emulsion, thus improving its bioherbicidal marketing potential.

Technical Abstract: In greenhouse and field experiments, an invert emulsion (MSG 8.25) was tested with dried, formulated spores of the bioherbicidal fungus Colletotrichum gloeosporioides f. sp. aeschynomene, a highly virulent pathogen of the leguminous weed Aeschynomene virginica (northern jointvetch), but considered “immune” against another more serious leguminous weed, Sesbania exaltata (hemp sesbania). A 1:1 (v/v) fungus/invert emulsion mixture resulted in 100% infection and mortality of inoculated hemp sesbania seedlings over a 21 day period under greenhouse conditions. In replicated field tests of the fungus/invert formulation conducted in Stuttgart, AR, and Stoneville, MS, hemp sesbania was controlled 85% and 90%, respectively. These results suggest that this invert emulsion expands the host range of C. gloeosporioides f. sp. aeschynomene, with a concomitant improvement of the bioherbicidal potential of this pathogen.