- Written by Kevin R. Lee Kevin R. Lee
- Published: 20 January 2020 20 January 2020
The genus Prunus includes the stone fruits, peaches, plums, cherries, apricots, and almonds. Many of these do not survive in zone 3, but many do. This article includes the ornamental shrubs, most of which bear edible fruit.
Here we will talk about the purple leaved sand cherry, the Mongolian cherry, the Russian almond, the Nanking cherry and the double flowering plum.
The purple leaved sand cherry, Prunus x cistena, is a beautiful shrub usually about a metre high. When the small pink flowers are present against the purple leaves, it is something to see. Unfortunately, it is not fully hardy and often experiences die-back, which is easily dealt with by pruning. A sheltered south facing location is the best bet. Even with the hardiness problem this shrub is so beautiful that it is still recommended.
The Mongolian cherry, Prunus fruticosa, is another attractive shrub, with jade green shiny leaves, white flowers and small sour red cherries. The Mongolian has a nice form. The woody structure can be a handsome "little tree", quite dense, usually about a metre high or more.
The Russian almond, Prunus tenella ,is another pink flowering beauty, subtle, you need to see it. It has a profusion of small pink flowers, which later produce a small edible almond. Don't let the size fool you , these little almonds have a full strong flavor. To get at the almond itself, first remove the tan hairy outer coat, then crack the seed cover; hidden inside is a tiny almond. Growing to about a metre, it's usually quite thick. I used to see more of the Russian almond; it is truly a prairie standard, highly recommended.
The Nanking cherry, Prunus tomatosa, named for its hairy leaves, is a classic. It has the potential to be a large shrub. I have seen old ones five metres high with stems measuring seven centimetres across. Most do not reach that size, mainly because it takes 40+ years to grow to that size and most shrubs are pruned. With white flowers followed by a profusion of delicious red cherries, its a toss-up whether this is an ornamental or a fruit-growing shrub. I have seen, though rarely, a variety where everything is identical to the description above, but with white cherries.
The double flowering plum, Prunus triloba 'Multiplex', is another prairie standard. Very similar to the Nanking cherry in size and form, but a little smaller, it is still a large shrub that can grow in time to four metres. Known for its flower show, its profusion of double pink 2.5 cm flowers is as close to a Japanese cherry event as we will get. It readily takes to what I call "little tree" pruning. I have seen then trained to a single stem that was quite effective.
The cherries are subject to Pseudomonas syringae, a sneaky, quiet disease. A bacterium like fire blight, it affects a different group of hosts. Similar in its methods to fire blight, it attacks the rose family stone fruits that are immune to fire blight: cherries, plums, apricots.
When these trees are infected, usually one of the symptoms is gummosis, which is an amber-like deposition of hardened sap that collects near cankers. The other commonly affected hosts here are lilacs. They are affected with classic blight symptoms, wilted discoloured flowers and leaves.
One favourite tree that can be outright killed by Pseudomonas is the beautiful Amur cherry. Last year, a homeowner noticed some wilting on her 40-foot Amur in the McKenzie Towne area. Several calls went out, some time went by, and some misdiagnosis occurred. In about three weeks, the tree had gone from a couple of wilted looking branches to being overwhelmed by the disease. Removing it quickly to avoid spreading the disease was the only option.