Refining pest management thresholds for water-deficit cotton production

Cotton is grown in the southern US under a range of irrigation deficit conditions from
dryland to full irrigation. The crop responds well to management and most University sponsored
research is conducted on well irrigated soils; however, there is a need to better define economic
profitability models that provide decision support under all conditions. The objective was to
evaluate the impact of thrips and stink bug management under three water-deficit (dryland,
partial, full) conditions. Measured responses included thrips abundance and boll injury during
the growing season followed by gross revenue adjusted for lint yield and quality. Both thrips
and stink bugs exceeded cooperative Extension recommended treatment thresholds and treatment
with insecticides produced expected changes in insect populations and plant response. Full
irrigation significantly increased gross revenue by $412 per ha compared partial irrigation and
$512 per acre compared to dryland. Although there were no differences in gross revenue
attributed to thrips treatment, treating stink bugs increased gross revenue by $300 per ha under
full irrigation and $400 per ha under partial irrigation; there were no differences under dryland
conditions. These data strongly suggest that researchers need to optimize pest management
thresholds for production under dryland conditions.