Evaluation of Bipolaris panici-miliacei as a bioherbicide against Microstegium vimineum

Control of economically important gramineous weeds has been overly dependent on chemical herbicides resulting in herbicide resistance and pollution. The development of a biocontrol technique may be an optional approach to weed control. Bipolaris panici-miliacei strain SX5-2 was isolated from diseased Microstegium vimineum plants. Pathogenicity, host range test, culture and mass production, crop sensitivity, formulation development and field trials were conducted to evaluate the potential of this strain for a bioherbicide. Pathogenicity tests showed percent incidence was up to 90% at a conidial suspension concentration of 10(5) conidia/mL on M. vimineum under greenhouse conditions and more than 80% in the field. Host range tests on 57 species in 17 families determined that B. panici-miliacei strain SX5-2 was safe for rice, wheat, sorghum, soybean, cotton, vegetables, Zoysia japonica turf and most dicotyledonous plants. Only maize and sugar cane were severely infected. Pathogenicity bioassays showed that the strain could control those seven tested gramineous weeds Digitaria sanguinalis, Panicum virgatum, Echinochloa crus-galli, Microstegium japonicum, Microstegium nodosum, Sorghum sudanense and Leptochloa chinensis in the main dryland and paddy fields. Culture and mass-production studies revealed that combined submerged and solid fermentation with bran and sawdust was feasible for mass production of conidia. Therefore, based on virulent pathogenicity and feasible mass production, B. panici-miliacei may have a promising potential to be developed into a bioherbicide for biocontrol of grass weeds in most crops but not in susceptible maize or sugarcane.

Automated summary

Bipolaris panici-miliacei SX5-2 strain showed high pathogenicity in Microstegium vimineum, with a wide host range but severe infection in maize and sugar cane.