Desmedipham Phytotoxicity to Sugarbeets (Beta vulgaris) Under Constant Versus Variable Light, Temperature, and Moisture Conditions

Abstract

The type of growth chamber environmental regime used altered the response of sugarbeets (Beta vulgarisL. ‘USH-9′) to desmedipham [ethylm-hydroxycarbanilate carbanilate(ester)]. No difference occurred in growth retardation following treatment at different times of day when standard growth chamber constant day/night temperature and light cycles were used. When temperatures were programmed and light intensity varied during the day/night cycles, approximating out-of-doors daily cyclic conditions, the herbicide caused greater injury following morning treatments and less injury following late afternoon treatments. Data obtained in the growth chamber under the typical constant day/night pattern did not agree with field derived information; data obtained using the programmed temperature and varying light regime agreed well with field data and with known action of desmedipham. Plants stressed for moisture after treatment were less retarded than plants turgid at treatment; but both showed relationships to time of day at treatment similar to those noted above. Moisture stress prior to treatment diminished growth retardation by desmedipham, and reversed the treatment time of day effect.