Beet Western Yellows

On lettuce, symptoms of beet western yellows rarely develop until plants reach rosette stage. At this point in crop development, the older leaves begin to turn yellow. This yellowing continues until all the oldest, lower leaves are bright yellow, or (less frequently) almost white, with the main leaf veins remaining green. Yellowed leaves often have a thick, brittle texture. Yellowing can progress until the wrapper leaves adjacent to the head also turn yellow, and head color may be unacceptably l