Variability in Time and Space of Meloidogyne incognita Fall Population Density in Cotton Fields
AbstractThree cotton fields infested with Meloidogyne incognita were intensively sampled in the fall for 3 years (1996 to 1998) to determine if intensive sampling for M. incognita, for which spatial location is important, was necessary every year in a continuous cotton system. Two composite soil samples (20 cores each), taken over an area covering one-third of the field length and two rows wide, were averaged to represent that area (row-location combination). Each field (except one) had 24 areas assayed for changes in M. incognita population density (Pf) over a 3-year period. At all three sites, Pf was higher during fall 1998 than fall 1996. There were no differences in Pf between rows within a year or between years (no. row × year interaction) at any of the sites. At all three sites, there was a consistent difference each year in Pf among locations in a field (no. year × location interaction). At each area, M. incognital/500 cm³ was labeled for one of four Pf classes: 250, 250 to 999, 1,000 to 2,499, and = $2,500. Management of root-knot nematode would likely be altered as classification changed. The areas that were reclassified by two classes or more after 1 and 2 years ranged from 0 to 29% and 25 to 54%, respectively. The risk of underestimating Pf of M. incognita was higher in one site 2 years after the initial intensive sampling procedure, whereas in another site there was little change in Pf 2 years after initial sampling. Sampling frequency will need to be decided on a field-by-field basis.
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).