Abstract

Ibrahim KahramanoÄ?lu

This study was conducted to determine the minimum dose of pre-planting pendimethalin giving satisfactory control efficacy (>90%) on Amaranthus retroflexus L., a troublesome weed of spring planted potato fields. Experiments were conducted in 400 ml plastic pots with 6 replications each containing ~500 g soil and pots were arranged in the completely randomized design in controlled greenhouses. 100, 80, 60, 40, 20 and 0 (control) % of the registered dose of pendimethalin were tested. Herbicide solutions were prepared in distilled water and applied to air-dried soil. Treated soil was mixed by shaking in a plastic bag for 2 min, dried for 1 h and placed into plastic pots. Thus, 10 seeds were sown into every pot and transferred into greenhouses. Plants height, number of leaves and herbicide symptoms measured at 1st, 3rd , 5 th, 7th, 14th, 21st and 28th days. At the 28th day plants were cut at soil surface, thus fresh and dry weights were determined. Dry weight data of the experiments were subjected to nonlinear regression analyses and the effective doses of pendimethalin causing 90% reduction in dry weight (ED90) were estimated. Results indicated that 1092.5±48.7 g a.i. ha -1 pendimethalin gives 90% reduction in dry weight of A. retroflexus.