|Lewis, E. E. - VIRGINIA TECH UNIVERSITY|
Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: October 1, 2004
Publication Date: October 1, 2004
Citation: Kokalis-Burelle, N., Lewis, E.E. 2004. Effects of Pre- and Post-plant Applications of Steinernema riobrave on Root-Knot Nematode Populations and Galling of Tomato. Journal of Nematology. 36:327-328. Interpretive Summary: Entomopathogenic nematodes (EPN) and their associated symbiotic bacteria have shown promise in controlling plant pathogenic nematodes including species of Meloidogyne. Previous greenhouse and growth chamber studies for effects on root-knot nematode have included species of Steinernema and Heterorhabditis and their associated bacteria Xenorhabdus spp. and Photorhabdus spp. respectively. The objective of these studies was to test the field efficacy of several rates of Steinernema riobrave infective juveniles applied both pre-plant and post-plant for control of the root-knot nematode Meloidogyne incognita on tomato in Florida. The combination of high pre-plant rates and post-plant application of EPN's reduced numbers of root-knot nematode juveniles isolated from soil over the growing season to the greatest degree. It was also shown that soil temperature at the time of EPN application can greatly affect results.
Technical Abstract: Several rates of the entomopathogenic nematode Steinernema riobrave applied pre- and post-plant were evaluated for control of Meloidogyne incognita on tomato in Florida microplots. Experiments were performed in spring and repeated in fall of 2001. Treatments were four pre-plant rates of S. riobrave, untreated, 0.5, 1.0, and 2.0 x 109 infective juveniles (IJ's)/a, combined with one post-plant application rate of 1 x 109 (IJ's)/a. Root-knot nematode (RKN) populations were assessed pre-plant/pre-treatment, post-treatment, 7 days after planting (DAP), 14 DAP, after post-plant treatment, and at end of season. In the spring, with cool soil temperatures in the early season, application of additional EPN after planting improved plant growth and root condition but did not significantly reduce galling. Area under the development curve for RKN populations showed low rates of EPN's applied early in the spring increased numbers of RKN's isolated from soil while higher rates reduced them. The combination of high pre-plant rates and post-plant application of EPN's reduced numbers of RKN juveniles isolated from soil over the growing season to the greatest degree. In the fall, soil temperatures were high early in the season and the post-plant application of EPN's did not enhance plant growth, root condition or reduce galling. However, higher pre-plant rates of EPN's had lower amounts of galling while more RKN juveniles were isolated from soil over the season. The fact that populations remained high but the juveniles did not infect the roots indicates that EPN may interfere with RKN mobility or host location. Also, soil temperature at the time of EPN application can greatly affect results.