Location: Horticultural Crops ResearchTitle: Differential response of Meloidogyne, Pratylenchus, Globodera, and Xiphenema species to the nematicide fluazaindolozine
|WRAM, C - Oregon State University|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2020
Publication Date: 11/3/2020
Citation: Wram, C.L., Zasada, I.A. 2020. Differential response of Meloidogyne, Pratylenchus, Globodera, and Xiphenema species to the nematicide fluazaindolozine. Phytopathology. 110(12):2003-2009. https://doi.org/10.1094/PHYTO-05-20-0189-R.
Interpretive Summary: Plant-parasitic nematodes are microscopic soil worms that attack the roots of plants and cause significant loss in yield to this crop. Farmers lack reliable methods to reduce the impact of nematodes on plant productivity. In recent years, there have been new nematicides, chemicals that kill nematodes, that have become available for us by growers to manage plant-parasitic nematodes in a diversity of crop production systems. This research was conducted to evaluate the effects of one of these new nematicides, fluazaindolizine, on the mobility and reproduction of a diversity of plant-parasitic nematodes. Results indicate that the response of nematodes to the nematicide varied among the nematodes tested. The dose needed to kill nematodes varied 100-fold among the different nematodes. Understanding how plant-parasitic nematodes respond to nematicides is a step forward in the proper stewardship of these nematicides.
Technical Abstract: Although widespread and economically important, there are few control measures to combat plant-parasitic nematodes (PPN). To fill this void, several new nematicides, including fluazaindolizine, have been developed. To ensure the longevity of these compounds, more information is required regarding their impacts on reproduction and mobility of different PPN genera. In this study we focused on fluazaindolizine. Two types of experiments were conducted. A microwell assay system was used to generate 24-hr dose-response curves for four PPN genera exposed to fluazaindolizine. Dose-response curves were generated for second stage juveniles (J2) of three Meloidogyne species (M. incognita, M. chitwoodi, and M. hapla); additionally, 4, 10, and 2 geographically distinct populations of M. chitwoodi, M. hapla, and M. incognita, respectively, were screened. The response of one population each of Pratylenchus neglectus (mixed stages), Globodera ellingtonae (J2), and Xiphenema americanum (mixed stages) and two populations of Pratylenchus penetrans (mixed stages) were also determined. A greenhouse with M. hapla, M. chitwoodi, and M. incognita was then conducted to evaluate the 24-hour effective dose (ED) of fluazaindolizine that resulted in the immobility of 25%, 50%, 75%, and 100% of M. incognita J2 (ED25, ED50, ED75, and ED100). Nematodes were exposed to fluazaindolizine for 24 hr in solution and then were inoculated on susceptible tomato ‘Rutgers’ to quantify reproduction post exposure. In microwell assays, the average 24-hr ED50 concentrations for M. hapla, M. chitwoodi, and M. incognita were 777.9 ppm, 544.8 ppm, and 245.7 ppm, respectively. Meloidogyne hapla had the most variation in its 24-hr ED50 with concentrations ranging from 175 ppm to greater than 1,900 ppm. Globodera ellingtonae was had the lowest 24 hr ED50 concentration, 74 ppm, of all the genera tested. Pratylenchus spp. were unaffected by fluazaindolizine even at the highest concentrations tested. Xiphenema americanum was the only species to show some reversibility of the effects of fluazaindolizine, but had a 24-hr ED50 that fell in the range of the Meloidogyne species tested. In the greenhouse study, reproduction of all of the Meloidogyne species was suppressed when pre-exposed to fluazaindolizine for 24 hr. Meloidogyne chitwoodi was the least sensitive with reproduction still reaching 62% of the untreated control after a pre-exposure to 115 ppm, whereas M. incognita and M. hapla at the same exposure dose had reproduction rates of 27% and 36% of the untreated control, respectively.