Hi Scotty. The following are some of the deseases that potatoes are prone to.
The worst problem that can occur is blight, which is particularly prevalent in wet years. The leaves go yellow and brown and start to curl. Eventually the haulm (the stalks) seems to fall to pieces. The potatoes develop black patches, which eventually turn into a slimy, evil-smelling rot. Do not plant potatoes on ground that was affected the year before (either from potato or tomato blight). Earth (hill) them up well to keep the spores from the tubers. If necessary, spray with the appropriate copper-based fungicide, preferably in wet years before blight appears. Look out for resistant varieties.
Another common disease is potato scab, which disfigures the surface of the tubers. To avoid it occuring, do not grow do not grow potatoes on ground that has been recently limed or manured. Other diseases include violet root and blackleg.
The main pests are slugs and wire-worms, both of which eat holes in the tubers. Other pests can include cutworms and potato cyst eelworms.
Robin