FENOXAPROP EFFICACY AND PHYSIOLOGY IN VARIOUS GRASS SPECIES (ORYZA SATIVA, AMINO ACIDS, ECHINOCHLOA CRUS-GALLI, ZEA MAYS, AUXIN)

The ethyl ester of fenoxaprop at single applications of 0.1 or 0.17 kg ai/ha or two applications of 0.1 kg ai/ha 10 to 14 days apart did not adversely affect rice (Oryza sativa L.) grain yield, panicle weight, seed weight and seed germination when applied prior to the booting stage for both sprinkler-irrigated and flooded rice. Barnyardgrass (Echinochloa crus-galli) control in rice was good to excellent from fenoxaprop at rates greater than 0.1 kg ai/ha when applied at various stages up through the five- to six-leaf stage. Barnyardgrass in the tillering stage was the most difficult to control. Rice yield correlated well with week control ratings. The relative tolerance of five rice cultivars to fenoxaprop was evaluated in the greenhouse. The following relationship was established: Starbonnet = Lemont > Newbonnet = Labelle > Lebonnet. Rice yield was not affected when treated with fenoxaprop at 0.17 kg ai/ha when flooded at 1, 3, 5, 7, or 10 days after treatment, but at 0.34 kg ai/ha yields increased with increasing flood date. A delay in flooding until 5 days after treatment was necessary to prevent excessive yield losses when the high rate was used.;Laboratory results indicated that the treatment of corn (Zea mays) with fenoxaprop-ethyl resulted in an overall accumulation of free amino acids. A 520-fold increase in arginine and a 220-fold increase in histidine occurred. DNA content per gram of fresh weight increased 62% with the highest fenoxaprop-ethyl concentration. IAA-induced elongation of first internode sections of corn was inhibited in the presence of fenoxaprop-ethyl.