ARS | Publication request: INFECTION OF THE WEED SESBANIA EXALTATA BY SOIL-INCORPORATED MICROSCLEROTIA OF THE FUNGUS COLLETOTRICHUM TRUNCATUM

Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 16, 1995
Publication Date: N/A

Technical Abstract: Microsclerotial (MS) propagules of Colletotrichum truncatum were produced in submerged culture (Jackson et al., Mycol. Res., in press). When dried MS were encapsulated in formulations of pregelatinized corn flour (PCF), pregelatinized corn starch (PCS) or both, soil-incorporated PCF MS incited the most disease on Sesbania exaltata seedlings. Placing formulated MS on Noble water agar resulted in high levels of sporogenic germination for PCF MS (~50-fold increase over MS alone) and secondary MS formation for PCS MS. C. truncatum was recovered from seedlings of S. exaltata grown in MS-infested pasteurized soil from 3 days after seeding until seedling collapse after 8 days. By day 6, C. truncatum was recovered from 24% of seedling samples taken from 7 mm above to 7 mm below the soil line but from only 3% of more distal samples. In total, 65% of the C. truncatum isolated was from plant tissues adjacent to the soil line. Light and SEM microscopy ystudies determined that MS germinated intermittently on S. exaltata seedlings in situ. Germination was myceliogenic and sometimes sporogenic.