DAMAGE TO ROOTS OF MUSA CULTIVARS BY RADOPHOLUS-SIMILIS WITH AND WITHOUT PROTECTION OF NEMATICIDES

Damage to root systems of five Musa cultivars caused by Radopholus sim ilis was assessed over two crop cycles. In addition, a comparison was made of the response to two nematicide treatments made during the firs t cycle, 3 and 6 months after planting. The cultivars differed in thei r degree of susceptibility. Population levels of R. similis were highe r on untreated susceptible cultivars than on treated ones. Nematode po pulation densities did not differ among nematicide treatments for the resistant cultivar (Yangambi km5). Population levels from the untreate d resistant cultivar were significantly lower than populations from tr eated susceptible cultivars. The root systems of susceptible Musa clon es were severely damaged by R. similis. On the selected sucker for the second crop, 85% of the entire root system of susceptible cultivars w as necrotic, compared to only 5 % on the resistant Yangambi km5. The u se of nematicide significantly increased the health (more functional r oots, less corm damage) of the susceptible cultivars, but this treatme nt produced no apparent improvement to the health of the root system o f the nematode resistant cultivar Yangambi km5.