Managing yellow margined leaf beetle (Microtheca ochroloma Stål) in organic cole crops with trap cropping

Organic vegetable production is a growing industry in the United States. However, pest pressures have slowed the growth of this industry in southern states. The yellow margined leaf beetle (YMLB), Microtheca ochroloma Stål, is a major pest of organic cruciferous crops. Turnip is a preferred host, so the purpose of this experiment was to determine if turnip is a viable trap crop for YMLB on organic farms. A 581 m² area on an organic farm near Starke, FL was divided into 6 treatment plots. Three plots had turnip planted as a trap crop around the plots while the other three plots had unplanted outer areas. During the spring of 2012, turnip plants were sprayed weekly with Entrust^®. During the winter of 2012/2013, the turnip was sprayed if average YMLB exceeded 1 per plant. Two cash crops, mustard and napa cabbage, were planted in each plot. The number of YMLB on 10 randomly selected plants from each cash crop and the trap crop in 2012/2013 was recorded weekly. An injury assessment was conducted at harvest time. In 2012, after the first 2 weeks, there were significantly less YMLB recorded from both mustard and napa cabbage in the trap crop plots. The average injury rating was also smaller in the trap crop plots. In 2012/2013, the YMLB population was low so there were few differences among treatments. Therefore, using turnip as a trap crop appears to be a viable option for organic crucifer growers.