Scanning electron microscope observations on spiral nematode (Helicotylenchus multicinctus)-infested banana roots

Banana (Musa sp., Cavendish sub-group, cv. Grand Nain [AAA]) roots-infested with the spiral nematode, Helicotylenchus multicinctus, were collected fro m a four-year-old banana plantation in Zemach Banana Experiment Station. Ro ot segments with lesions were processed for observation by scanning electro n microscopy. Electron micrographs of root cortical tissue reveal that the nematodes are localized at a depth of only 4-6 cells from the epidermis. Th e nematodes migrate in the root cortical parenchyma parallel to the root lo ngitudinal axis and lap eggs within the tissue. Histologically, the root le sion consists of a defined group of parenchymal cells which collapse in rea ction to the nematode invasion. In most cases die spiral nematode was accom panied by mycelia of various fungi.