摘要:

Pycnidiospores assignable toSeptoria avenaeFrank and asci and ascospores assignable toLeptosphaeria avenariaWeber were isolated from cereals and grasses in Canada, but studies herein reported concern only oat-infecting isolates. Macrospores of the oat-infecting organism occurred on green and mature oats during the summer, on oat stubble in the early autumn, and occasionally on old stubble in spring. Microspores were found on mature oats and stubble at the end of August; they occurred abundantly on stubble throughout the winter, and were still present on a few collections in May and June. Immature perithecia were found on stubble in April and perithecia with mature ascospores on June 16, but stubble moistened in the laboratory before that date had discharged mature ascospores.Cultures derived from macro-, micro-, and asco-spores produced macro- and micro-spores in culture; of the 82 cultures derived from single ascospores all except seven formed pycnidia and macrospores, and of the 100 cultures derived from single microspores, all except four formed macrospores. No perithecia were found in culture on various media undar different conditions, or when isolates were paired in various combinations. The macrospores and ascospores have one nucleus per cell, the nuclei of each spore originating from one nucleus. Microspores are uninucleate.Newly discharged ascospores germinated in about 1 hour and macrospores in a few hours in water. Microspores took at least 40 hours to germinate on solid media.In culture, low temperature favored microspore formation and high temperature macrospore formation. Microspores were also found in cultures ofSeptoria nodorumandS.oudemansii, but not in cultures ofL.avenariaf. sp.triticea.The means of overwintering of the organism are discussed; it is considered that, although macro- and micro-spores are available in the spring, ascospores are probably the principal spring inoculum.Oat-infecting isolates did not infect the other cereals or certain grasses, and the oat-infecting isolates were obtained only from oats. The International Rules of Botanical Nomenclature are interpreted to mean that with the erection of the f. sp.triticea, the type automatically becomesL.avenariaf, sp.avenaria(imperfectS.avenaef. sp.avenae).

ISSN:0008-4026    

DOI:10.1139/b57-011

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Cultures were established from pycnidiospores assignable toSeptoria avenaeFrank collected on wheat, oats, barley, rye, and grasses in Canada. Those cultures that were nonpathogenic on oats produced, in most cases, perithecia and viable ascospores ofLeptosphaeria avenariaWeber, as well as the asexual spores. Cultures were also established from asci and ascospores assignable toL.avenariacollected on wheat, oats, barley, rye, and grasses. Those that were nonpathogenic on oats produced, in most cases, pycnidiospores ofS.avenaeas well as the sexual spores. Many of the isolates produced slight to trace infection on the wheat variety Gaza and trace infection on barley. Oats, rye, and certain grasses were immune. It is considered that the isolates are a plurivorous group slightly pathogenic on wheat and found on the senescent parts of other cereals and grasses, and that they are best assigned toL.avenariaf. sp.triticea. No microspores were found in any of the cultures. Perithecia with viable ascospores formed in 123 cultures out of 164 established from single ascospores, some of the lines being maintained by single ascospore transfer up to five generations. This special form is therefore regarded as homothallic.

ISSN:0008-4026    

DOI:10.1139/b57-012

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

An emended description ofSphaeronaemella fimicolaMarchal refers this species to its proper taxonomic position among the Hypocreaceae, with both perfect and imperfect stages very similar to those ofS.helvellaeKarsten as described by Seeler. The species, found in nature on dung of various herbivorous animals (rabbit, deer, and cow), is culturable, growing more consistently on V-8 vegetable juice agar than on other media tried, most vigorously in association with other fungi likeAspergillus repensorMicroascus sordidus, or with addition of filter-sterilized Czapek's broth in whichA.repenshad been grown. Fruiting in culture has been erratic; only early transfers from isolations made from field material yielded mature perithecia in pure culture, and then only on V-8 agar; later transfers fruited only in intimate contact with the mycelia of the other two fungi mentioned.

ISSN:0008-4026    

DOI:10.1139/b57-013

出版商:NRC Research Press    

年代:1957

数据来源: NRC