Diversity of plant-parasitic nematodes associated with kiwi trees and related relationship with selected soil variables in Limpopo Province, South Africa

Kiwifruit, a temperate plant, is becoming one of the most important crops in tropical regions with high altitudes in Limpopo Province, South Africa. During a survey on plant-parasitic nematodes in five kiwifruit orchards, eight nematode species were identified from the soil and root samples across the orchards in Limpopo Province. Out of the 75 soil samples, the most prevalent nematodes encountered were Helicotylenchus species, followed by Meloidogyne hapla and Scutellonema brachyurus, with 26.83, 17.07, and 9.76% frequency of occurrence, respectively. Prominence Values (PVs) of Helicotylenchus (2719.34), and Meloidogyne (2169.28) were higher when as compared to those of other plant-parasitic nematode species. The results indicated no significant correlation between the plant-parasitic nematode species associated with kiwi and pH. However, Ca% had a significant positive correlation with Nanidorus minor, Tylenchorhynchus, Scutellonema brachyurus, Xiphinema vuittenezi, M. hapla, and Paratylenchus straeleni. In contrast, Helicotylenchus dihystera and Ca% exhibited a significant negative correlation, but Ca% did not correlate with Rotylenchus brevicaudatus. Besides, soil density had no correlation with H. dihystera but a significant negative correlation with R. brevicaudatus. In conclusion, the high altitude-kiwifruit-producing regions suggested the existence of a considerable range of plant-parasitic nematodes, with the highest nematode diversity in Nooyenskopje orchards. Thereby suggests the need to assess the damage potential of the identified nematode species on kiwifruit trees. The attended management strategies for further studies are required to evaluate the crop damage caused by plant-parasitic nematodes on the kiwifruit orchards.