European plum is the best known of cultivated plums, having been grown the longest and widely distributed. Their sweetness and tartness may vary as well as their colors. Most are self-fertile and do not require cross-pollination but may benefit from it. European plum is longer lived than Japanese plum (and its hybrids), but it starts fruiting later. There are six cultivars of European plum being observed in cultivar trials at Carandale.
American plum is native to North America and spans six hardiness zones (3-8) and grows in most soils with a pH level between 5.5-7.5. It is moderately drought tolerant. All the fruit is some shade of red when fully ripe, and most drop on the ground when ripe. Fruit quality and fruitfulness are highly variable, but some trees produce abundantly and consistently.
The term “cherry plum” as used in this website refers to cherry and plum hybrid crosses. Two cultivars were established in the test plot in 2004. ‘Compass’ is later blooming than most cultivars in need of cross-pollination, which may reduce its effectiveness as a pollinizer for many cultivars. It is a very upright tree and the few small cherry-like fruit it produces have a tart skin. Four ‘Sapalta’ trees transplanted well and adapted to the site. All four remain healthy and productive. The skin is tart but the fruit is a good choice for processing. The dark purple fruit make an attractive finished product.
Manchurian plum is native to Eastern Asia. It is said to be hardy and vigorous. It does not have a typical tree form. The very long thorns on the older branches are probably typical. New growth from the previous year has no thorns. It had a growth surge in the 2011 growing season. This growth surge continued in 2012 despite drought conditions, indicating good drought tolerance. There was no fruit set, most likely due to the general freeze losses that affected a majority of the cultivars. Seedling plums are genetically different from each other, so every plant will have slightly different characteristics. Accordingly, all observations will have to be generalized and broadly interpreted.
Many Japanese-American hybrid plums have been introduced over the last 150 years. The best of them have the fruit quality (size, flavor, sweetness) of the Japanese parent and the hardiness and disease resistance of the American parent. Preliminary results from the plum cultivar trials illustrate the broad range of characteristics and marketing potential of this mostly overlooked fruit species. Genetic variability makes plums adaptable to almost any temperate climate region.
Apricot is another Prunus species with a short chilling requirement and early bloom period that make it site sensitive and limit its adaptability for commercial production. It is being incidentally observed in the Carandale test plot. Observation has been limited by misidentification and inaccessibility to cold hardy cultivars.
This is a selection of a naturally occurring hybrid of apricot (P. armeniaca) and Myroblan Plum (P. cerasifera) from central Asia. The trees had incredible vegetative growth at Carandale, but they bloomed sparingly and never set fruit, even with cross pollination available from the adjacent plum trial.They were removed from the test plot in 2008.