Infection and development of Ustilago syntherismae in Digitaria ciliaris

Ustilsgo syntherismae (Schwein.) Peck, which causes loose smut of crabgrass, infects its host systemically and destroys seed production. Greenhouse experiments were carried out to investigate the mode of infection, the disease incidence that can be obtained by artificial inoculation and the conditions necessary for optimum infection, cross-infection on southern and smooth crabgrass, and the reasons for the late observance of the disease. U. syntherismse infected southern crabgrass, Digitaria ciliaris (Retz.) Koeler, by both seed-borne and soil-borne teliospore inoculum. Disease incidence was high (84-91%) in some treatments. Higher rates of teliospore application resulted in larger percentages of smutted plants. When infesting the potting mixture, the highest percentages of smutted plants were obtained when infestation and planting were done at the same time. Earlier or later planting resulted in fewer smutted plants. When planting at various depths, greater numbers of smutted plants were obtained when inoculated seed were planted 0.5 to 1.0 cm below the surface versus planting on the surface or at greater depths. The appearance of 50% of infected plants' first panicles (in greenhouse experiments) was delayed by 4.5 weeks compared to the emergence (50%) of first panicles from healthy plants. In cross inoculation experiments, southern and smooth crabgrass plants developed smut only when inoculated with spores collected from large and smooth crabgrass~ respectively.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Plant Pathology

Department dc:contributor.department

Plant Pathology

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1990

Author dc:creator

• Johnson, David Alan

Chair dc:contributor.committeechair

• Baudoin, Antonius B.

Committee members dc:contributor.committeemember

• Derr, Jeffrey F.
• Kok, Loke T.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-12172008-063243

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/46286