A system for evaluating the phytotoxicity and/or injury of plants is described. Plants are planted in row sections and a cart is used to pass a radiometric sensor over the row sections. The cart has a radiometric sensor assembly positioned above the row section. Each sensor assembly generates a data signal and a computer receives and stores the data signals. The field cart is positioned above the row sections and measures the existence of plants in the row section and the quantity of vegetation in the row section.