Rev 06/03/2025
Chromadorea Rhabditida Tylenchina Tylenchoidea Pratylenchidae Pratylenchinae
Pratylenchus loosi Loof, 1960
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:
Pratylenchus loosi is reported in tea production in many areas of the world. It has been distributed in cuttings and other planting material.
In 2025, P. loosi was intercepted in California USA in a shipment of Camellia sp. from China (Martin, 2025).
Designated as an A-rated pest by California Department of Food and Agriculture
Migratory endoparasite of plant roots.
Camellia sinensis (tea) an important economic host/
Pratylenchus loosi enters roots of plant hosts by penetrating cell walls with stylet thrusts. It feeds, reproduce, and moves Through cells within the tissue . It may complete its entirewhile spending its entire life cycle in the root nut can also be found in the soil surrounding Within the roots, feeding is primarily in the root cortex.
As in other species of the genus, P. loosi has six life stages: egg, four juvenile stages, and adults. Reproduction requires both females and males, and males are common (Martin, 2025). The first juvenile stage is completed in the egg; all other stages are in the roots and soil. All stges can feed on root cells after hatching from the egg.
Pratylenchus loosi survives the winter in infected roots or soil as eggs, juveniles, or adults. During spring, when plants are growing, eggs hatch to commence the life cycle within roots or in the rhizosphere soil (Martin, 2025).
Ecophysiological Parameters:
A damaging past in tea production.
Within the root, nematode feeding on cortical tissue causes necrosis of cortical cells, cell breakdown, and formation of cavities. Necrosis may appear as lesions that expand as the nematodes move lengthwise within the infected roots. Some nematodes may leave the root, enter the soil, and re-enter the root at a different site, causing a new infection.
Infected plants may have fewer feeder roots and stunted root growth. Above-ground growth may exhibit general symptoms of an impaired root system, including lack of vigor, dieback, chlorotic and small leaves, and reduction of yield. In general, root lesion infection results in plants exhibiting symptoms of chlorosis, wilting and stunting (Chitambar et al., 2018; Gnanapragasham et al., 2018; Martin, 2025).
Host Plant Resistance, Non-hosts and Crop Rotation alternatives:
Early work with this nematode suggested that increasing potassium fertlization offset the damage effects.
Reduce Dispersal and Spread: The largest risk forspread is with infected host plants for planting. The nematode can also be moved with contaminated growing media and plant debris, and with contaminated machinery and equipment. Irrigation or run-off water can also move nematodes (EPPO, 2025; Martin, 2025).
Chitambar, J. J., Westerdahl, B. B., and Subbotin, S. A. 2018. Plant Parasitic Nematodes in California Agriculture. In Subbotin, S., Chitambar J. (eds) Plant Parasitic Nematodes in Sustainable Agriculture of North America. Sustainability in Plant and Crop Protection. Springer, Cham
EPPO Database. 2025. Pratylenchus loosi. https://gd.eppo.int/taxon/PRATLO Accessed 5/8/2025
Gnanapragasham, N. C., and Mohotti, K. M. 2018. Nematode parasites of tea. In Sikora R. A., Coyne D., Hallmann J., & Timper P. (Eds.), Plant parasitic nematodes in subtropical and tropical agriculture (pp. 584� 616). CAB International.
Loof, P. A. A. 1960. Taxonomic studies on the genus Pratylenchus (Nematoda). Tijdschrift voor Plantenziekten 66:29-90.
Martin, H.J. 20245 California Pest Rating Proposal for Pratylenchus loosi Loof, 1960, Tea Lesion Nematode, California Department of Food and Agriculture, Sacramento, California, USA.