Abstract
The involucral nectaries of cotton [Gossypium hirsutum] flowers in field plots in Arizona were tagged and inoculated with spores of Aspergillus flavus on the day of anthesis. To determine the degree of plant water stress, water potentials were measured in the plots between 1200 and 1230 hr on the tagging day. Tagged bolls were harvested at maturity and the seeds assessed for A. flavus. Seed infection levels were affected significantly by water potentials on the day of anthesis and inoculation, with the highest infection levels generally occurring in seed from plants with water potentials between -1.6 and -1.9 MPa.