OCCURRENCE OF PERITHECIA OF GIBBERELLA-FUJIKUROI MATING POPULATION-A (FUSARIUM-MONILIFORME) ON MAIZE STUBBLE IN NORTHERN VIETNAM

Perithecia of Gibberella fujikuroi were found on old maize (Zea mays) stalks in northern Vietnam. Single ascospores from these perithecia pr oduced cultures of the anamorph Fusarium moniliforme but perithecia we re not produced in single spored cultures. Eleven single ascospore cul tures originating from 3 perithecia were crossed with known tester str ains and were shown to belong to mating population A of G. fujikuroi. Three strains were identified as A+, six as A- and two strains that di d not produce perithecia when crossed with the testers. Some combinati ons when crossed with each other produced fertile perithecia of G. fuj ikuroi, confirming the potential for perithecial production by these s trains in the field. Samples of maize kernels were collected from mark ets and F. moniliforme was isolated from these sources. These isolates also belonged to the A population and contained both + and - strains. Perithecia produced by compatible crosses and sclerotial-like structu res produced by incompatible crosses were sectioned and their morpholo gy examined. Only perithecia produced by compatible strains produced a layer of mother cells capable of producing asci.