Intercropping effect of two melon cultivars and four medicinal plant species on the pest control and fruit yield in melon

In order to evaluate the effects of medicinal plants (Thymus vulgaris L., Rosmarinus officinalis L., Lavandula angustifolia Mill., Mentha piperita L.) with melon intercropping on pests control and fruit yield in melon, and to reduce the use of chemical pesticides, a factorial experiment was performed based on a completely block randomized design with three replications in 2017. Experimental factors included two melon cultivars ("Khatoni" and "Khaghani"), chemical control and four medicinal plant species (thyme, rosemary, lavender, and peppermint) that were cultivated as additive intercropping among melon bushes. The ANOVA results showed that the effects of cultivar on weevil (Acythopeus curviostris) population, number of healthy and damaged fruit and fruit weight, the effects of intercropping on weevil, whitefly and aphid population, number of healthy and damaged fruit and fruit weight, and the interaction effects of two factors on weevil and aphid population and number of healthy and damaged fruit were significant at 5% probability level. Based on the results of the experiment, chemical control had the greatest effect on pest population control in both melon cultivars. Among the intercropping treatments, peppermint had the greatest effect in reducing the weevil population in both melon cultivars. Moreover, intercropping of "Khatoni" with peppermint and "Khaghani" with peppermint, lavender, and rosemary had positive effects on reducing the aphid population. However, intercropping of both melon cultivars with all four medicinal plant species had no effect on whitefly population control. Based on the results of this study, and in order to keep the sustainability of crop ecosystems, intercropping of melon with some medicinal plants such as peppermint can be considered to reduce the population of some pests on melon.