Russian olive (Elaeagnus angustifolia) is a tough, drought tolerant and beautiful landscape tree. Its silver leaves and shaggy black bark make it beautiful summer and winter, and its small size allows it to fit almost anywhere.
However, it is prone to a particular disease that causes dramatic branch death, called phomopsis canker. If your Russian olive is infected with phomopsis, you'll see a whole branch or section of the tree suddenly flag and die. Don't panic! This disease is common and rarely spells death for your tree. Cut out the flagging section a minimum of 12 inches behind the canker (preferably to the next branch) and burn it immediately or dispose of it in your municipal garbage. Disinfect your pruning tools in between cuts with a 10% bleach solution or gas line antifreeze.
Help your Russian olive recover by keeping a weed-free mulch ring around the base and watering it deeply once every two weeks during dry spells. This will help it regrow the branches lost to the canker. Keep your tree pruned into an open shape to allow maximum air flow. This lowers humidity within the canopy and helps stop disease from spreading. Good sanitation - pruning out and destroying cankers, and raking up and removing fallen leaves - will go far towards preventing phomopsis from spreading through your tree.
|Comparison of healthy (left) and flagging (right) Russian olive leaves|