Effect of colletotrichum leaf spot disease on growth parameters of colocynthis citrillus and cucurbita pepo. – S. E. Udo, B. E. Madunagu, E. J. Umana and A. A. Markson
Colletotrichum lindemuthianum was isolated and identified as the main pathogen causing leaf spot disease of Colocynthis citrillus (melon) and Cucurbita pepo (pumpkin) in Cross River State, Nigeria. The pathogen’s symptoms (observed in May) were known to have impaired growth processes in the hosts. Growth parameters were read at 21 and 45 days post inoculation (21 and 45 Dpi). There was reduction in the Leaf area ratio (LAR) of the diseased plants as infection progressed. The Net assimilation rate (NAR) was higher in infected C. pepo at 21 Dpi (2.3×10-3 gmcm2day-1) and 45 Dpi (3.2×10-4 gmcm2day-1) than the healthy samples (9.0×10-4 and 2.4×10-4 gmcm2day-1 respectively). Reduction in NAR for C. citrillus was observed at 45 Dpi (-1.6×10-3). This general situation led to reduction in the relative growth rate (RGR) of the assay cucurbits at 45 Dpi.