Effects of Environmental Factors and Cultural Practices on Parasitism of Alfalfa by Ditylenchus dipsaci
AbstractCool humid weather enhanced development and reproduction of Ditylenchus dipsaci in alfalfa in laboratory and field studies in Utah. Relative humidity and nematode reproduction were positively correlated (P 0.05), whereas air temperature and nematode reproduction were negatively correlated (P 0.05). The greatest number of nematodes per gram of alfalfa tissue was found in nondormant Moapa alfalfa tissue at St. George during April, whereas the greatest numbers of nematodes were found in dormant Ranger alfalfa in June at West Jordan and Smithfield. There was 100% invasion of both resistant Lahontan and susceptible Ranger alfalfa plants at soil moisture levels of 61-94% field capacity. Fall burning of alfalfa to control weeds reduced, and spring burning increased, the incidence of invaded plants, nematodes per gram of plant tissue, and the mortality of susceptible Ranger (P 0.01) and Moapa (P 0.01) alfalfa plants over that of plants in nonburned control plots. Fall burning also reduced and spring burning increased the incidence of invaded plants (P 0.05), but had no influence on nematodes per gram of plant tissue or the mortality of resistant Lahontan and Nevada Synthetic XX alfalfa over those of plants in control plots. Key words: alfalfa stem nematode, air temperature, mortality, relative humidity, reproduction, resistance, soil moisture, susceptibility, Ditylenchus dipsaci, Medicago sativa.
Copyright and Permissions
All material published by the Society of Nematologists (SON), except for papers prepared by United States and Canadian government employees, is copyrighted and protected under the U.S. copyright law. Under the Copyright Act of 1976, the term of copyright for materials registered by an organization is 75 years from the date first published. Before publishing any manuscript, SON requires that authors transfer full and complete ownership of any copyright to SON by signing a JON Page Charge/Copyright Form (.pdf). SON then registers the copyright. Subsequent use of published materials requires written permission from the SON and may be obtained by contacting the current Editor-in-Chief and state where and how the material will be used.
The author warrants that the article is an original work not published elsewhere in whole or in part, except in abstract form, and that the author has full power to make this grant. If portions of the article have been published previously, then the author warrants that permission has been obtained from the copyright holder and the author will submit a copy of the permission release with this copyright transfer form.
SON shall claim no proprietary right other than copyright. Authors and coauthors retain the right to revise, adapt, modify, or otherwise use all or part of the article in future works of the author(s), such as press releases, lectures, and reviews, provided that all such use is for the personal noncommercial benefit of the author(s). All patent rights are retained by the author(s).