Botanically speaking, a prune is a plum, but not all plums can become prunes. Only dried plums are called prunes, though the term is commonly applied to fresh plums that can be dried successfully. They are high in fiber and contain modest amounts of vitamin A, vitamin B3 and vitamin B6. It takes about 18 hours at 185ºF to remove about 80 percent of the moisture in prunes. South American producers have demonstrated $700-900 / dry ton creates planting incentives.