Plant-parasitic nematodes of ginger (Zingiber officinale Rosc.) in Southern Ethiopia

Abstract

Summary Ginger is one of Ethiopia’s most widely cultivated crops, and is second-most-important spice, yet its productivity is constrained mainly by bacterial wilt and plant-parasitic nematodes (PPN). Despite their impact, the occurrence, distribution and population density of PPN associated with ginger in Ethiopia remains limited. To address this knowledge gap, a survey was conducted in 2022 across eight major ginger-producing districts in southern Ethiopia, collecting 330 soil and rhizome samples. Nematodes were extracted and identified using morphological and molecular methods. Six PPN genera were identified, including: Meloidogyne , Scutellonema , Helicotylenchus , Rotylenchulus , Crossonema and Mesocriconema. Meloidogyne was the most prevalent genus, occurring in 86% of the fields with densities ranging from 102 to 368 second-stage juveniles (J2) per 100 ml of soil and a frequency of occurrence (FO) of 20-92%. It was also the only genus recovered from ginger, with densities reaching up to 1158 J2 per 10 g rhizomes with roots and 100% FO. Other genera included Rotylenchulus , Scutellonema and Helicotylenchus with densities up to 72, 108 and 116 individuals (100 ml soil) −1 , and 68, 60 and 84% FO, respectively, while Mesocriconema and Crossonema had the lowest FO. Molecular analysis, including D2D3 of 28S rDNA, NADH dehydrogenase subunit 5, cytochrome c oxidase subunit I and cytochrome c oxidase subunit II, further confirmed the presence of seven PPN species, with Meloidogyne javanica being the most prevalent root-knot nematode, followed by M. incognita . Importantly, Rotylenchulus borealis and Scutellonema paralabiatum are reported for the first time from ginger in Ethiopia. These findings provide a foundation for improved monitoring and management of PPN, supporting sustainable ginger production in the region.