Lettuce (Lactuca sativa)-Red Rib (Rib Blight)

Latest revision: 
March 2023

Cause Unknown but believed to be physiological. Tests have not associated red rib with soil types, pH, or fertilizing practices.

Symptoms Brownish-red spots on leaves, mainly on ribs, enlarge to become fairly wide bands, up to 0.75 by 3 to 4 inches long. The bands are diffuse, not sharply edged. The disorder may affect one or two ribs of the outside leaves, but often the discoloration continues through to inner leaves from these points. Larger bands of affected tissue may crack, allowing rot organisms to enter.

Cultural control The variety 'Salinas' and other salinas types are susceptible. 'Ithaca' and 'Summertime' do not crack and rot.