Comparison of damage levels caused by Radopholus similis and Helicotylenchus multicinctus on bananas in Uganda

Field surveys were done in 1997 and 1998 in Masaka district, Uganda, an are a which is experiencing a decline in banana production, to assess level of damage caused by nematodes Radopholus similis and Helicotylenchus multicinc tus at farm level. Ten farms within a radius of 2 kin were selected and nem atode damage assessed. The major nematodes encountered were Pratylenchus go odeyi, R. similis and H. multicinctus. P. goodeyi and H. multicinctus were more abundant than R. similis but R. similis had a stronger and significant correlation with root damage. A subsequent pot trial examined pathogenicit ies of R. similis and H. multicinctus in pure and mixed cultures on tissue cultured-banana plantlets. R. similis alone and in mixed population reduced root fresh weight significantly, and the percentage of root necrosis range d between 22.8-41.6% and 18.3-45.5% for March 1998 and March 1999 trials, r espectively. The difference in damage caused by R. similis alone and in mix ed population was not statistically significant, and was higher than the da mage caused by H. multicinctus alone. There were no significant differences in pathogenicity among the R. similis isolates from different parts of Uga nda.