J. Mudiope, P.R. Speijer, N.R. Maslen and E. Adipala
Yam (Dioscorea spp.) is a traditional tuber crop in tropical Africa and a principle source of carbohydrates. Crop yields are still low, with susceptibility to nematodes being one of the main constraints. In 1997, a survey was carried out in the major yam growing regions of Uganda to establish the nematode species profile with this crop. Tubers of various cultivars were collected and observed for incidence of root-knot nematode galls and tuber skin cracks. Nematodes were extracted from I cm3 taken out of the tuber surface. Incidence of root-knot sympsoms and tuber cracks were low, i.e., less than 1 on a scale of 0 (no symptoms) to 3 (severe symptoms). Pratylenchus spp. dominated the samples followed by Meloidogyne spp. Positive correlations (P < 0.05) between
Pratylenchus spp. and severity of cracks were observed. Increasing and sustaining yam production in Uganda should include the search for cultivars with sources of Pratylenchus spp resistance and control measures such as selection of clean nematode free tubers and or heat therapy of yam setts.