Mulch as a potential management tool for lesser cornstalk borer, Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae), in bean (Phaseolus vulgaris L.)

Lesser cornstalk borer (LCB) is a serious pest of bean and many other crops. Mulching is an effective method to control weeds and provide shelter for predatory insects, and also helps to maintain soil moisture for plant vigor. Field experiments were conducted in small “micro” plots at two different locations (fields A and B) in summer and repeated in fall, 2007. The treatments were arranged in a randomized complete block design with five replications at both locations. At field A, treatments were bare ground, plots with mulch, and plots with weeds (original weed cover) while at field B, treatments were only bare ground and mulched plots. The mulch was obtained from a crop of sunn hemp (Crotalaria juncea L.) planted at another location. Data were collected on plant mortality, plant parameters (weight, length, and height of healthy plants), and population levels of predators. LCB attack was less (P ≤ 0.10) in mulched plots compared to the bare ground plots, considering a number of factors such as location and background of field, season, and amount of rainfall. Greater numbers of healthy plants were found in mulched plots compared to bare ground and plots with weeds. In general, weight, plant height, and total length were greater in mulched compared to other treatments. Treatments did not affect potential predators of LCB. Evidence suggests that LCB attack is reduced by mulches or weeds around host plants.