A systems approach to pest management thresholds for cotton production

Cotton production takes place in the southern US under a range of irrigation conditions from dryland to fully irrigated. However, most pest management threshold research is conducted on well-irrigated land and there is a need to better define insect action thresholds that support production under a range of conditions that address variable irrigation capability. The objective of this project was to sequentially evaluate the impact of thrips and stink bug control under three water-deficit (zero, 50%, and 100%) conditions. Measured responses included thrips abundance and boll injury during the growing season as well as yield and lint fiber quality at harvest.  Data indicate that both thrips and stink bug insecticide applications were highly effective at reducing target insect populations.  However, there were no observed differences in lint yield or lint value under dryland conditions regardless of insecticide applications.  Under partial and full irrigation treatments, thrips insecticide applications did not increase yield, whereas stink bug treatments had a positive yield response.  These data strongly suggest that dryland production fields require fewer insecticide inputs and therefore the Extension recommended action threshold should be increased for dryland production.  Reducing insecticide inputs to obtain the same lint yield and lint value will generate a higher return on initial investment in dryland cotton production.