Wild Plum Identification and Wild Plum Fungal Disease

(Question)

We live in the Timmins area up North and we are trying to identify a tree we have growing in our yard. It started growing and now has oddly shaped green puffs and small green fruits with pits growing together on its branches. The green puffs that appeared alongside the green fruit have now shriveled up and turned black. What is this type of tree?

tree

(Answer)

 

The identity of your tree is more than likely a wild or American Plum (Prunus americana) or could be mistaken for a Canada Plum (Prunus nigra). Both are natives of North America growing in Zones 3-10  in the US and Canada. Some hybrids can survive up to Zone 1!

The leaves are alternate, simple, and single toothed. The fruit is fleshy, roundish, about 1 inch with a seed.  American plum fruit has bloom (the whitish powder that gives plums their waxy appearance) in your picture. The Canada plum has a shiny skin. It is red to yellowish red when mature in late August. On young stems the bark is orange-brown to dark red-brown and  is smooth and shiny. Older stems are dark and break into large, thin scales.

The fruit you describe on your tree branch as puffed is a deformed wild plum that has turned black. The same branch, carries normal shaped immature wild plums, that are still a light green in colour. I know the identification of the tree is correct as only wild plums, specifically American plums, get a disease in which fruits become abnormal, blacken, and eventually wilt or dry on the same branches as normal plums.

Plum pocket or bladder plum is a disease caused by a fungus . The scientific name for the fungus is Taphrina communis. This is a rare occurrence and causes unripe plums to become deformed, large, pocket like and eventually blacken and become dry. The disease can be reduced organically by removing or pruning off the infected plums before they are covered with spores and move to other plums. Having a tidy orchard and only pruning in dry conditions can also stop the fungus from spreading. Be sure to clean your pruning tools with bleach or alcohol when you are done pruning infected fruit or branches for structure. Burn the waste or discard the trimmings to the landfill far away from your orchard.