Hirsutella rhossiliensisand Verticillium chlamydosporium as Biocontrol Agents of the Root-knot Nematode Meloidogyne haplaon Lettuce
AbstractHirsutella rhossiliensis and Verticillium chlamydosporium infected second-stage juveniles (J2) and eggs of Meloidogyne hapla, respectively, in petri dishes and in organic soil in pots planted to lettuce in the greenhouse. In vitro, H. rhossiliensis produced 78 to 124 spores/infected J2 of M. hapla. The number of J2 in roots of lettuce seedlings decreased exponentially with increasing numbers of vegetative colonies of H. rhossiliensis in the soil. At an infestation of 8 M. hapla eggs/cm³ soil, 1.9 colonies of H. rhossiliensis/cm³ soil were needed for a 50% decrease in J2 penetration of lettuce roots. Egg-mass colonization with V. chlamydosporium varied from 16% to 43% when soil was infested with 8 M. hapla eggs and treated with 5,000 or 10,000 chlamydospores of V. chlamydosporium/cm³ soil. This treatment resulted in fewer J2 entering roots of bioassay lettuce seedlings planted in the infested soils after harvesting the first lettuce plants 7 weeks after infestation with M. hapla. Hirsutella rhossiliensis (0 to 4.3 colonies/cm3 soil), V. chlamydosporium (500 to 10,000 chlamydospores/cm3 soil), or their combination, added to organic soils with 8 M. hapla eggs/cm³ soil, generally did not affect lettuce weight, root galling, or egg production of M. hapla. However, when lettuce was replanted in a mix of infested and uninfested soil (1:3 and 1:7, v:v), egg production was lower in soils with V. chlamydosporium than in soils without the fungus. Both fungi have potential to reduce the M. hapla population, but at densities below 8 eggs/cm³ soil.
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).