A polymeric spray shield assembly adapted to be connected to a support frame moved over plants growing in spaced rows from the earth and to be moved along the earth between the rows of plants while liquids such as herbicides not intended for contact with the plants in the rows are sprayed onto weeds between the rows of plants. The spray shield assembly comprises a polymeric spray shield having an inner surface defining a channel opening through an open side and front and rear ends of the spray shield, a top wall portion being adapted to have means attached thereto for suspending the spray shield from the support frame and through openings adapted to receive connector assemblies through which liquids are sprayed into the spray shield, and dependent opposite side wall portions. Stiff polymeric slotted end closure sheets are attached across the open front and rear ends of said channel to help retain the spray. Spaced weed knock down bars extend between the opposite side wall portions adjacent the open side of the channel and are adjustable to afford spacing the side wall portions at different distances.