Effect of NPK Fertilization on Cassava Mosaic Disease (CMD) Expression in a Sub-Saharan African Region

Abstract

The influence of NPK fertilizer on the incidence, severity and gravity of cassava mosaic disease (CMD) was investigated using eight genetically improved cassava varieties and eight local farmer's varieties. The study was carried out in a savannah region (Gandajika) in D.R. Congo at two locations. The varieties were planted with and without NPK fertilization. Application of NPK fertilizer significantly (P<0.05) increased CMD incidence, severity (AUDPC) and gravity overtime compared to the trials without fertilizers for all the improved cassava varieties evaluated. The CMD incidence remained below 30% of infected plants for improved cassava varieties and reached 100% of plants for local varieties during the six months trial. The same trend was observed for CMD gravity (number of infected leaves per plant) that was below 50% for improved varieties while reaching 100% for all the local varieties at 6 MAP. High incidence and gravity of CMD were observed on local varieties just one month after planting. NPK fertilizers increased significantly the CMD incidence and gravity compared to control site during the first month after plantation. Thereafter, the effect of NPK fertilizer on CMD symptom expression was not noticeable since all the plants from local varieties were infected regardless of the fertilization regimen.

Performance Evaluation of Four Novel Cassava (Manihot esculenta Crantz) Accessions to Different Fertilizer Types in Awka, Anambra State, Nigeria

“…It was shown that there was no significant effect of fertilizer on the disease severity of cassava plants. This is in disagreement with [33], who reported that NPK fertilizer application significantly increases CMD incidence and severity compared to trials without fertilizers. The disagreement observed in this investigation could have been as a result of high resistance of the improved cassava varieties used in this experiment to disease and pests.…”

Field Evaluation of Some Cassava Cultivars against the African Cassava Mosaic Disease in the Humid Forests of Cameroon

“…Taken into consideration that the severity of local cultivars and an improved cultivar (8034) had severity of CMD higher in the leaves than in the cultivars TMS92/0326 and TMS961414. It is therefore evident that, a decrease in the cassava leave surface area followed by a decrease in the photosynthetic activities will result in a decrease in the crop to produce tubers; it has been demonstrated by Nkongolo [23] in his PhD thesis that CMD causes mosaic and leaf distortion, leading to defoliation and severe plant stunting.…”