Leaf roll symptoms vary depending upon the stage of infection. Plants from infected seed tubers are stunted and immature leaves may have internal chlorosis. Mature leaves may be pale green, stiff and unrolled, and may have purplish edges. Tubers from plants infected in the current season develop fine lines of discoloration in the tuber. Spindle Tuber Spindle tuber is a serious disease of seed potatoes caused by the spindle tuber viroid.
Plants infected with spindle tuber viroid are upright, dwarfed and much thinner than normal vines.
The stems are often more branched and branches form very sharp angles where joined to the stem. Affected tubers are dwarfed and are usually narrow and spindle-shaped. Eyes are numerous and the tubers are often cracked. Spindle tuber is spread by insects such as aphids, grasshoppers, Colorado potato beetles and flea beetles, as well as seed-cutting knives, planters and infected seed. Mosaic is caused by potato viruses A, X, S and Y, alone or in combination.