Author : Hoesni Heroetadji, R.

Summary : Height of sugarcane variety Phil 56226 grown in 4,500 cc of potted baked soil was reduced by 7 percent within 18 weeks and 8.4 percent within 20 weeks when inoculated with 2,000 Helicotylenchus dihystera as compared with the control. At this inoculum level, fresh shoot and root weights also reduced by 33 percent and 62.5 percent, respectively, within 20 weeks. The roots were sparse, lack secondary and tertiary rootlets, with dark colored spots or lesions at the root tips, and generally the root systems had deteriorated. The primary roots were blunt. The nematode number recovered increased by 4.6 times within 20 weeks. These indicated that H. dihystera was parasitic on and pathogenic to sugarcane. H. dihystera was found to be an ecto-and a semi-endoparasite on roots of corn, tomato, and itchgrass (Rottboellia exaltata), and as an endoparasite in the root of Amaranthus spinosus. Very good hosts of H. dihystera were A. spinosus, centrosema pubescens, R. exaltata and Purslane (Portulaca oleracea); good hosts were wild sweet potato (Ipomoea triloba), tomato ( (Lycopersicon esculentum var VC-11-1), cotton (Gossypium hirsutum var. Deltapine 16), corn (Zea mays var. DMR 2) and wiregrass (Eluesine indica). Some of the affected plants had stunted growth, reduced and necrotic root systems, and chlorotic leaves. With the highest inoculum level (400 nematodes/pot), Xiphinema insigne reduced fresh root weights of sugarcane by 34 percent as compared to the control. Top growth was not affected. The roots were sparse with slight swelling, curling of the tips, and generally dark colored. A 2.5-fold increase in nematode number was recorded within 20 weeks compared with the initial population. Tomato (L. esculentum var. VC-II-I) and itchgrass (R. exaltata) were considered good hosts of X. insigne. The inoculated plant did not exhibit any perceptible symptoms. However, jungle rice (Echinocloa colona), itchgrass (R. exaltata), and wiregrass (E. indica) showed a malformation of the roots, indicating that X.