Effect of soil placement on the activity of herbicides on Cyperus rotundus L. *

Summary: The effect of herbicide placemem in the soil on control of Cyperus rotundus L. was studied in the greenhouse with EPTC, alaehlor, norfiurazon, perlluidone, napropamide, trifluralin, and naptalam, EPTC was the mosl active herbicide, increasing the number of sprouts per tuber but inhibitmg bud development at an early stage of growth. The effect was greatest when EPTC was incorporated with the soil around the tubers. The effects of alaehlor were similar, but higher doses were required. Another active herbicide, norfiurazon, was taken up by the roots but its effect was to produce small, chlorotic leaves, Perfluidone was mosl effective when incorporated into the soil around the tubers or when placed in a layer 1 cm above them. Very little effect of napropamide trifluralin and naptalam was observed. In studies of growth and deveiopmenl with different planting depths, C. rotumtus produced basal bulbs, roots and most of its early reproductive parts in a layer of soil 1–3 cm from the surface, irrespective of the depth at which the tubers were planted. Shoots etncrged from 35 im deep but not from 50 cm.