Effect of Amaranthus quitensis on parsley for dehydration yield

weeds are a severe problem in many horticultural crops but information about weed competition on parsley (petroselinum crispus (mill.) nym) yield is lacking. the objectives of this study were to determine the critical period for amaranthus quitensis kunth control in parsley and to quantify the influence of a. quitensis density on parsley yield. the critical period was variable between years and weed densities and ranged between 3 and 44 days in duration. in both years, a. quitensis densities of more than 30 plants/m2 can account for up to 70 % of yield loss. the results indicate that a. quitensis can significantly reduce parsley yields even at low densities if the weed is not controlled in the appropriate period.