Mature leaves may be pale green, stiff and may have purplish edges. Tubers from plants infected in the current season develop fine lines of discolouration in the tuber. Topkilling Spindle Tuber - Spindle tuber is a serious disease of seed potatoes and is caused by the spindle tuber viroid. Plants infected with spindle tuber viroid are upright, dwarfed and much thinner than uninfected plants. 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. Removing diseased plants, ensuring that the entire plant is removed. Planting whole seed. Avoiding leaf contact by people and equipment during field operations.