Under greenhouse conditions, annual bluegrass (Poa annua L.), common groundsel (Senecio vulgaris L.), shepherd's purse [Capsella bursa-pastoris (L.) Medicus], small nettle (Urtica urens L.), canola (Brassica napus L. ssp. napus), and pea (Pisum sativa L.) differed in sensitivity to ultraviolet (UV) radiation. Of the weed species, annual bluegrass was the least sensitive; whereas, among the crop species, canola was about sevenfold more sensitive than was pea. The sensitivity of a species to UV radiation was highly dependent upon its stage of development. The study indicates some potential for using UV radiation to control weeds, but the method needs further investigation to unravel the selectivity of the methods and potential health hazards.
