Study on the agronomic evaluation and disease resistance of eleven improved cassava varieties was carried out in Rivers State University Teaching and Research Farm in a Randomized Complete Block Design (RCBD). The eleven varieties assessed are TMS 30572, TMS 98/0510, TMS 98/0581, TMS 98/0505, TMS 92/0326, TME 419, TMS 01/1371, TMS 01/1368, TMS 07/0593, TMS 95/0289 and TMS 96/1632 were evaluated for plant height, leaf number, number of branches, number of flowers, insect infestation and disease incidence. The plant height of the cassava varieties revealed that eight varieties (TMS 01/1371, TMS 01/1368, TMS 30572, TME 419, TMS 98/0505, TMS 96/1632, TMS 98/0510 and TMS 07/0593) are tall varieties while TMS 98/0581, TMS 92/0326 and TMS 95/0289 are short varieties. The highest leaf number was recorded in TMS 01/1371 but the tall varieties like TMS 01/1368, TMS 96/1632 and TME 419 had low leaf number. TMS 98/0581, TMS 92/0326 and TMS 95/0289 were shown to have scanty leaves. TMS 01/1371 was significantly higher (P<0.05) than other varieties in plant height, leaf number and branches. Four varieties flowered namely TMS 07/0593, TMS 01/1371, TMS 30572 and TMS 98/0505. TMS 30572 and TMS 92/0326 were highly susceptible to both African Cassava Mosaic and Xanthomona sp. (Bacterial blight diseases) while TMS 95/0289, TMS 01/1368 and TMS 98/0505 were less susceptible to African Cassava Mosaic virus disease alone. Insect infestations (White fly: Bemisia sp. and Mealybugs: Phenacoccus sp.) on the tested varieties were significantly minimal though five cultivars (TMS 98/0505, TMS 96/1632, TMS 98/0510, TMS 98/0581 and TMS 95/0289) were completely resistant. Therefore, there is urgent need to withdraw the varieties that are susceptible, and use more of the varieties that are disease resistant for high crop yield, breeding and higher productivity.
Keywords: Resistance, Varieties, cassava, susceptibility and agronomic assessment.
