Aureobasidium Microstictum (Bubak) Cooke, The Casual Agent of Leaf Streak of Daylily (Hemerocallis L.), and Its Involvement in Spring Sickness of Daylily

Although daylilies are generally considered to be 'care-free,' several diseases including Leaf Streak and Spring Sickness can be problems. The causal agent of Leaf Streak is Aureobasidium microstictum, which is consideredto be synonymous with Collecephalus hemerocalli J.A. Spencer. Although the exact cause of Spring Sickness is unknown, there is an indication that the same fungus, A. microstictum, is involved in rot of tissue observed in plants with Spring Sickness. Objectives of this research were comparisons of isolates of A. microstictum and an isolate of C. hemerocalli, investigation on pathogenicity of A. microstictum, and the control of Leaf Streak.Regarding to the size of conidia, and shape of fungal structures including, hyphae, conidiophores, and conidia of eight isolates of A. microstictum and one isolate of C. hemerocalli were compared. C. hemerocalligenerally had the same morphological features as A. microstictum. In addition, the great variability in the size of conidia within each isolate was observed.The importance of wounding for penetration by the fungus or development of Leaf Streak was confirmed. Great diversity was found in both virulence among isolates of A. microstictum and susceptibility of cultivars.Direct injection of fungal spores resulted in rot of tissue, resembling the ones found in plants with Spring Sickness.Chemical control of Leaf Streak with fungicides were tested. Application of one fungicidal product, Benefit (thiophanate-methyl and iprodione), significantly decreased the disease severity, compared to the control. Despitethe extensive labor and the cost of chemical, fungicide application is the most plausible method to control Leaf Streak at this moment, due to lack of details of the disease cycle and mode of penetration.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Plant Pathology

Grantor dc:publisher

The Ohio State University

Year dc:date

1998

Author dc:creator

• Kobayashi, Hideka

Contributors dc:contributor

• M. Riedel, Richard

• Plant Pathology

Statement dc:rights

• unrestricted
• This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.

Language dc:language

English

Repository record dc:identifier

http://rave.ohiolink.edu/etdc/view?acc_num=osu1364222371

OAI identifier oai:identifier

oai:etd.ohiolink.edu:osu1364222371