Identification of Verticillium species and control methods for Verticillium wilt of potato in Manitoba.
Loading...
Date
2016
Authors
Molina Tirado, Oscar Ivan
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Manitoba is the second largest potato-producing province in Canada, after Prince Edward Island. Although the Manitoba average yield is slightly higher than the Canadian average, there are commercial fields with lower yield as a result of the pressure of diseases like Verticillium wilt, caused by Verticillium dahliae. In Manitoba and elsewhere, there is increased interest in the use of soil fumigation and application of composted manures to reduce Verticillium wilt. However, accurate quantification of V. dahliae inoculum in soil is needed for disease control decisions as well as to determine success of practices to reduce pathogen levels in soil. The traditional wet plating method for determination of Verticillium levels in soil is often prone to errors, laborious and costly. Therefore, the objectives of this thesis research were to: (i) evaluate control measures including compost addition and soil fumigation on Verticillium wilt and yield of potato, cv. Norland and cv. Russet Burbank; (ii) investigate the presence and quantity of microsclerotia-forming Verticillium species and its relation to Verticillium wilt in potato; and (iii) evaluate pathogenicity of V. tricorpus on potato, cv. Russet Burbank. In a replicated field study, composted manure did not prove to consistently reduce Verticillium wilt. Fumigation with metam sodium resulted in a reduction of V. dahliae levels in soil; however, only the lowest rate at 374 L ha-1 reduced Verticillium inoculum at planting by up to 40%, and increased marketable yield in cv. Russet Burbank by up to 24%. This result could potentially help growers to reduce environmental impact on organisms not targeted and the costs associated to the use of soil fumigant for the control of Verticillium wilt. Examination of soils and plants from 17 commercial potato fields determined the presence of the microsclerotia-forming Verticillium species V. dahliae as well as Verticillium tricorpus and Verticillium klebahnii in Manitoba. Nevertheless, the study did not focus on the presence of other non-producing microsclerotia species. The study optimized a real-time PCR method to identify and quantify V. dahliae, V. tricorpus and V. longisporum in soil and plant. A subsequent pathogenicity study of selected isolates of the Verticillium species demonstrated that only those of V. dahliae were pathogenic to potato.
Description
Keywords
Potato, Disease management, Verticillium wilt, Compost, Phytopathology, Soil-borne pathogen