Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 18, 1996
Publication Date: N/A
Interpretive Summary: Verticillium wilt, also called potato early dying disease, causes major crop losses each year on many crops including vegetables, cotton, olive and pistachio. The fungus causing this disease enters the plant near root tips. The beneficial fungus Talaromyces flavus can partially suppress the disease. T. flavus is thought to provide control by a combination of mechanisms, including production of an enzyme that leaks out of the fungal cell. One product of the reaction of this enzyme is hydrogen peroxide, which is very toxic to the pathogen. For the enzyme to be active, it must have the sugar glucose as a substrate. There is little glucose in soil, although some glucose is found at root tips. This work was undertaken to determine where T. flavus is found on and near roots and if the method of application of T. flavus or the crop plant affects the population size or location of T. flavus on roots. Higher populations of T. flavus were found don root tips than on roots, and in soil near roots rather than away from roots. The T. flavus was easily washed from roots, indicating only ssuperficial attachment. Populations of T. flavus were greater when the fungus was applied as a liquid drench rather than as granules. Colonization of potato, tomato and eggplant roots by T. flavus was similar. This information will be used by scientists in development of beneficial fungi for use in control of plant diseases.
Ascospores of Talaromyces flavus were applied to eggplant, tomato and potato as either a drench or in prill. In subsequent samplings, percentage colonization of roots was significantly greater than that of root tips. However, when populations of T. flavus were expressed as colony forming units/g fresh weight, recovery of T. flavus was significantly greater in root tips. Populations were lower in rhizosphere soil than from roots and root tips and populations in nonrhizosphere soil were the lowest of any location. Vigorous washing of the roots removed most of the T. flavus, indicating that T. flavus was superficially associated with the roots. Populations of T. flavus were greater when it was applied as a drench rather than in prill.