Influence of nutrition on the development of leafspot disease of fluted pumpkin (Telfairia occidentalis Hook F.) caused by Phoma sorghina

The effects of nitrogen and potassium fertilizers on the incidence and severity of leaf spot disease of fluted pumpkin (Telfairia occidentalis) were studied in 1991 and 1992 cropping seasons. The studies were conducted under rain-fed conditions at the experimental farms of Federal University of Technology, Owerri, Nigeria (05' 27' N:02'E). Nitrogen fertilizer (CAN) was applied to plots of fluted pumpkin at rates equivalent to 0, 40, 80 and 100kgN/ha/yr at each of two levels of potassium K (MOP) 0 and 80kgK/ha/yr. The incidence and severity of leaf spot disease were assessed at and between harvests. Water-soluble carbohydrate, ascorbic acid, protein, potassium, phosphorus and nitrogen contents were also measured at harvest. Results showed that severity of leaf spot disease for fluted pumpkin plants grown under 40kgN was significantly lower than those grown under 80kg and 100kgN. Nitrogen contents measured on harvested leaves in indicated that there was a significant correlation between foliar nitrogen content and leaf spot severity. An inverse correlation between disease severity and foliar contents of water-soluble carbohydrate was also obtained. Nitrogen appears to have the most influence on disease severity while potassium application had no apparent effect on disease development. Although marketable yield of leaves increased with increasing levels of nitrogen applied, high levels of nitrogen did not favour the production of pods by the crop.