Plants that are injured by overapplications of simazine develop yellow leaf margins. As injury symptoms progress, the entire leaf may turn yellow, eventually brown, and may end with the death of the plant. The vast majority of the incidents end with slight injury, followed by full recovery of the plants. Norflurazon interferes with the production of carotene in the plant. Without the carotene in the leaves, chlorophyll is destroyed, leaving the plant with no pigments in the foliage.
Leaves affected by norflurazon develop a unique, characteristic white color.
The pattern of development of the color is also unique. It begins at the base of the leaf and follows the veins. As with simazine, severe injury or death only results when norflurazon is grossly overapplied around relatively small plants. They all control weeds primarily through inhibition of root growth. They all also have low solubilities in water, so they stay close to the soil surface.