Impact of lemongrass intercropping on tomato yield response and insect abundance under organic culture

Tomato (Lycopersicon esculentum Miller) is one of the most widely grown vegetables, vulnerable to pests from planting to flowering and harvesting. Due to limited insect control resources approved by the Organic Materials Review Institute (OMRI) organic growers on the Delmarva Peninsula are facing significant pest challenges. Intercropping is one of the key farming strategies to increase crop productivity by suppressing pests and maintaining a stable population of natural enemies. This study was conducted for two years to determine the effect of the tomato-lemongrass (Cymbopogon citratus Stapf) intercropping system on tomato yield, the abundance and diversity of pests and beneficial insects. Using two organic tomato cultivars, Beefsteak and Brandywine Red, an experiment was designed on two organic fields, intercropped with lemongrass and without lemongrass. The results showed that high insect density in tomato-lemongrass intercropping than in non-intercropped plots. Moreover, more beneficial insects were recorded on tomato-lemongrass intercropped plots than in non-intercropped plots. Beefsteak intercropped with lemongrass on both fields had lower insect damage and higher marketable fruit weight than the non-intercropped tomato plants. Brandywine fruits had 19% and 60% insect and non-insect damage, respectively, two to three times more damage than Beefsteak. These results indicate that intercropping tomatoes with lemongrass may increase the marketable yield of selected tomato cultivars such as Beefsteak by increasing beneficial insect biodiversity and minimizing the utilization of agrochemicals.