Sesbania exaltata biocontrol with Colletotrichum truncatum microsclerotia formulated in ‘Pesta ’ granules

Abstract

was effectively controlled in soybean [Glycine max (L.) Merr.] field test plots over a 2-year testing period (1995–1996) with microsclerotia of the bioherbicidal fungus, Colletotrichum truncatum, formulated in wheat gluten-kaolin granules called ‘Pesta’. Weed control averaged 84 % and 88%, respectively, in plots treated pre-plant incorporated (PPI) at ‘Pesta ’ rates of 168 or 336 kg ha)1, and 71 % and 78%, respectively, in plots treated pre-emergence (PE) at ‘Pesta ’ rates of 168 or 336 kg ha)1 over the testing period. Post-emergence (POE) control averaged 30% and 50%, respectively, for the 168 and 336 kg ha)1 treatments, and was significantly less effective than either PE or PPI treatments. Although pathogenesis and mortality occurred in hemp sesbania tissues, satisfactory weed control was not achieved in plots treated at rates of 17 or 84 kg ha)1 with any of the application methods. Soybean yields were significantly greater in test plots treated PPI or PE, as compared to yields from test plots treated either POE, with inert ‘Pesta ’ granules, or from untreated controls. Microsclerotia formulated in ‘Pesta ’ granules exhibited excellent shelf-life, retaining high viability after storage for 10 years at 4 C. These results suggest that microsclerotia of C. truncatum formulated in ‘Pesta ’ granules offers an effective method for controlling this important weed and preserving the activity of this bioherbicide