Effect of border crops and intercropping on aphid infestation and the associated viral diseases in hot pepper (Capsicum sp.)

Abstract

Aphids are associated with loss in yield and quality of pepper crop due to damage they cause and the transmission of viruses in a non-persistent manner. The aim of the study was to determine the potential of border crops and intercrops in the management of aphids and the associated viruses in hot pepper production. Field experiments were carried out for two seasons in 2018/2019 at Rubona Research station, Huye District, Rwanda. Maize (Zea Mays L.), sorghum (Sorghum bicolor L.) and sunflower (Helianthus annuus) were tested as companion crops associated with hot pepper either as border crops or as intercrops. Randomized complete block design was used with four treatments and three replications per experiment. Data on aphid population, the virus disease incidence, the area under the disease progress curve (AUDPC), growth and yield of hot pepper were recorded. Diseased leaf samples were collected and analysed serologically to detect the viruses present in the experimental plots. Aphid-transmitted viruses; Cucumber mosaic virus, Potato virus Y and Pepper veinal mottle virus, and aphid species, namely Aphis gossypii and Macrosiphum euphorbiae were identified in the experimental plots. The use of maize, sorghum or sunflower as border crops or as intercrops significantly reduced (p < 0.05) the incidence of viral diseases in hot pepper compared with control at later stages of growth. At 12 weeks after transplanting (WAP), use of maize, sunflower or sorghum as border crops significantly reduced (p < 0.05) the incidence of viral diseases by 24%, 31% and 38% compared with the control in season one and by 32%, 54% and 46% in season two. Similarly, intercropping with maize, sunflower or sorghum was also effective in reducing incidence of viral diseases in hot pepper by 24%, 35% and 27% in season one, and by 39%, 39% and 32% in season two, respectively. The AUDPC differed significantly (p < 0.05) while the population of aphids did not differ (p > 0.05) among treatments for both experiments. Results revealed that maize, sorghum and sunflower can be utilized either as border crops or intercrops for the control of viral diseases in pepper production. This technology is environmentally friendly, easily adaptable and appropriate since the production of pepper is mainly done by resource-poor farmers.