Scanning Electron Microscope Observations on Spiral Nematode (Helicotylenchus multicinctus)-Infested Banana Roots

Abstract

Banana (Musa sp., Cavendish sub-group, cv. Grand Nain [AAA]) roots infested with the spiral nematode, Helicotylenchus multicinctus, were collected from a four-year-old banana plantation in Zemach Banana Experiment Station. Root segments with lesions were processed for observation by scanning electron microscopy. Electron micrographs of root cortical tissue reveal that the nematodes are localized at a depth of only 4-6 cells from the epidermis. The nematodes migrate in the root cortical parenchyma parallel to the root longitudinal axis and lay eggs within the tissue. Histologically, the root lesion consists of a defined group of parenchymal cells which collapse in reaction to the nematode invasion. In most cases the spiral nematode was accompanied by mycelia of various fungi.