QCANE and armyworms: To spray or not to spray, that is the question

Conventional advice to growers is that there is no significant economic benefit from attempting to control armyworms in recently harvested green-cane trash-blanketed fields. This is despite some severe defoliations, coupled with wide variation in temperature and armyworm densities. The simulation model QCANE was used to test this premise. A submodel, which simulates armyworm development (temperature mediated) and feeding, and control costs, was incorporated to predict threshold armyworm densities for different cost:benefit ratios across districts and harvest times. The model suggests considerable potential economic benefits from applying insecticides against armyworms. The submodel and its outputs require validating before it can be applied widely; an outline of a research program to provide this validation is presented.