Effects of leaf blight caused by Colletotrichum and Lasiodiplodia species on the growth and yield parameters of melons (Citrulus and Leganaria species)

Abstract

Melons (Citrullus lanatus (Thumb) Mansf. and Leganaria siceraria (Mol.) Standley) are vital vegetable crops in West Africa, valued for their  edible nutrient-rich seeds and oil. However, their production is impacted by leaf blight, while the economic yield loss caused by this  disease is not well documented. This study examined the effects of three blight-causing pathogens: Colletotrichum truncatum (Ct),  Colletotrichum gloeosporioides (Cg), and Lasiodiplodia theobromae (Lt) on the growth and yield traits of melon. Three melon cultivars (Bara,  Serewe, and Bojuri) were artificially inoculated with these pathogens in two field trials using a randomized complete block design with  four replicates. Data on growth and yield parameters (GYPs) were analyzed using analysis of variance (p<0.05). The pathogens  significantly affected GYPs depending on the cultivar. In Serewe cultivar, Lt significantly reduced vine length (from 82.9 to 28.2 cm) and  the number of leaves (from 74.3 to 39.2). In Bara, the three pathogens reduced the number of leaves and number of vines, while a  significant reduction of vine length was caused by Ct (from 98.2±9.9 to 42.4±7.7cm) and Lt (98.2±9.9 to 41.5±13.6cm). However, the GYPs  of Bojuri was unaffected by the three blight pathogens. The pathogens also reduced the number of fruits per/plant of Serewe cultivar  (from 7.8±2.6 to 3.1±0.6) and weight of fruits/per plant (from 8.0±5.0 to 1.6±0.9 kg) and all the evaluated yield parameters in Bara except  weight of fruits/plant which was only reduced by Ct (from 3.1±0.8 to 1.2±0.8 kg). Lasiodiplodia theobromae (95.7%) and Ct (92.9%) caused  the highest reduction observed in the weight of seeds/plant of Serewe and Bara, respectively. This study highlights significant yield losses  due to Colletotrichum and Lasiodiplodia species in Serewe and Bara melon cultivars, emphasizing the need for effective disease  management strategies.