Reproduction of Meloidogyne enterolobii on onion and potential yield suppression

Authors: POUDEL, NABIN - University Of Georgia; Davis, Richard; MCAVOY, TED - University Of Georgia; DUTTA, BHABESH - University Of Georgia; CHOWDHURY, INTIAZ - University Of Georgia

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2025
Publication Date: 4/15/2025
Citation: Poudel, N., Davis, R.F., Mcavoy, T., Dutta, B., Chowdhury, I.A. 2025. Reproduction of Meloidogyne enterolobii on onion and potential yield suppression. Journal of Nematology. 57:e2025-0005. https://doi.org/10.2478/jofnem-2025-0005.
DOI: https://doi.org/10.2478/jofnem-2025-0005

Interpretive Summary: Meloidogyne enterolobii, the guava root-knot nematode, is an emerging nematode species in the southern United States. To date, no studies have evaluated the host status of onions to this nematode. This study aimed to assess the reproduction and pathogenicity of M. enterolobii on Vidalia and red onion cultivars commonly grown in Georgia. Seven Vidalia onion cultivars (Monjablanca, Rio Del Sol, Sapelo, Sweet Magnolia, Tania, Vidora, and 1011) and three red onion cultivars (Red Duke, Red Halen, and Red Maiden) were evaluated. Each cultivar was inoculated with 8,000 eggs of M. enterolobii in a repeated greenhouse trial with six replications each. Twelve weeks post-inoculation, plants were harvested to determine reproduction and pathogenicity based on the reproduction factor (Rf = final nematode population/initial nematode population) and reductions in bulb and shoot weights, respectively. All tested cultivars were susceptible to M. enterolobii, with final nematode levels increasing above the inoculation level, though significant differences were observed. Vidora, Tania, and 1011 exhibited the most nematode reproduction, while Sweet Magnolia and Sapelo had the least. All red onion cultivars showed significant reductions in both bulb and shoot weights, whereas among the Vidalia cultivars, only 1011 exhibited notable reductions in bulb and shoot weights. These findings suggest that onions are suitable hosts for M. enterolobii, and that the nematode's reproduction and pathogenicity vary with onion type and cultivar. Red onion cultivars appear to be damaged more severely than Vidalia onion cultivars.

Technical Abstract: Meloidogyne enterolobii is an emerging root-knot nematode species in the southern United States. To date, no studies have evaluated the host status of onions to M. enterolobii. This study aimed to assess the reproduction and pathogenicity of M. enterolobii on Vidalia and red onion cultivars commonly grown in Georgia. Seven Vidalia onion cultivars (Monjablanca, Rio Del Sol, Sapelo, Sweet Magnolia, Tania, Vidora, and 1011) and three red onion cultivars (Red Duke, Red Halen, and Red Maiden) were evaluated. Each cultivar was inoculated with 8,000 eggs of M. enterolobii in a repeated greenhouse trial with six replications each. Twelve weeks post-inoculation, plants were harvested to determine reproduction and pathogenicity based on the reproduction factor (Rf = final nematode population/initial nematode population) and reductions in bulb and shoot weights, respectively. All tested cultivars were susceptible to M. enterolobii, with Rf values greater than 1, though significant differences were observed. Vidora, Tania, and 1011 exhibited the highest Rf values, while Sweet Magnolia and Sapelo had the lowest. All red onion cultivars showed significant reductions in both bulb and shoot weights, whereas among the Vidalia cultivars, only 1011 exhibited notable reductions in bulb and shoot weights. These findings suggest that onions are suitable hosts for M. enterolobii, and that the nematode's reproduction and pathogenicity vary with onion type and cultivar.