Submitted to: Society of Nematologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/30/2017
Publication Date: 12/31/2017
Citation: Myers, R.Y., Mello, C.L., Ragasa, T. 2017. Azadirachtin powder for control of root-knot nematodes in tomato. Society of Nematologists Proceedings. Volume 49, page 517.
Technical Abstract: USDA ARS Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center, 64 Nowelo St., Hilo, HI 96720. Root-knot nematodes cause root galling and yield reductions in many vegetable crops, including tomato. Three organic treatments to improve root growth and reduce nematode infestation were evaluated in a greenhouse potted plant bioassay. Two month old tomato plants in sterilized potting media were treated with either azadirachtin powder, effective microorganisms, a wettable powder containing 2 Trichoderma species, or water. In the first experiment, each pot was inoculated with 1000 Meloidogyne incognita juveniles and evaluated for nematode penetration by staining the roots with acid fuchsin twenty days later. The number of galls in azadirachtin amended plants was reduced by 59% compared to plants supplemented with Trichoderma or water. Roots treated with effective microorganisms were significantly heavier than those in the other treatments. Due to the increased size of the root systems, there was no difference in the number of galls per gram of root when using effective microorganisms compared with the azadirachtin application. In a second experiment to evaluate nematode reproduction, tomato plants were inoculated with 3000 M. incognita juveniles and harvested after seven weeks. Azadirachtin powder significantly reduced the nematode population whereas the other treatments had no effect. The population factor was 2.62 when amended with azadirachtin and 5.12, 5.12, and 5.10 when Trichoderma spp., effective microorganisms, and water were added. The root mass of azadirachtin treated plants was significantly lighter than the other treatments and resulted in a noticeably different root architecture with longer, finer lateral roots. No differences in plant height were observed. Azadirachtin has potential for lowering root-knot nematode populations in tomato production however yield studies need to be conducted to confirm that the resulting reduction in root size has no negative effect on crop yield.