Toronto – We have 5 fruit trees/bushes that are 5 years old. Early July last year our cherry tree had one branch die back, leaves curled down to back, wilted and discolored to fall colours. Cut that one off but a couple of weeks later the rest of the tree did the same thing and although I hoped it was a one year thing the tree did not come back this year. It was dead. It is now starting in our plum all over at the tips of the branches, new growth, and starting to work back. Per my book it is the symptoms are fire blight. Can I save the plum and if yes how. Garden centre expert said little hope and just prune back severely (and fertilize?) and hope. He said he lost 4 trees to an apparently similar problem.
Second part of question is do I need to worry about so far healthy plants cherry bush (5 feet away), Peach (20 feet away), and Pear (30 feet away). Also have blackberry, blueberry and raspberry bushes in the vicinity.
Do I rip out the plum to save the rest? Do I need to do something to sterilize the soil? There are also cedars and other small bushes nearby. The garden is raised and L shaped with the foot being about 20’Lx12W’ and the upright being about 20’Lx7’W.
Fire blight is a very serious disease which affects principally members of the family Rosacaeae – including cherries, plums, apples, and pears. Other members of this family which it also affects include some ash species, cotoneasters, hawthorns, and raspberries.
It is a bacteria disease, caused by the bacteria Erwinia amylovora. Typically the infection will start in the the blossoms of the tree, move onto twigs, then branches and the main stem of the plant. There is no cure. The best treatment is regular pruning and removal of infected twigs or branches. Avoiding overhead irrigation is also advised as splashing water it a common way of spreading the infection.
You can try and save your plum tree by pruning out the affected areas as least 24 inches past the area affected by the blight. Make sure that your tools are clean and disinfect between cuts and before using on another tree or shrub. You can also make sure that your plum (and other shrubs and trees) are getting the appropriate fertilization as over fertilization leads to rapid growth, and this abundant new growth is most at risk of becoming infected by the blight. To determine how much nitrogen you actually need to add consider testing your soil annually. Another spread prevention technique is to try and control sucking insects, such as aphids, which can carry the disease between your plants.
You probably do not need to worry about your blackberries and blueberries, as they are not in the family affected by the blight. However your cherry, raspberries, peach and pear are susceptible.
Given how many of your plants might catch fire blight you could consider removing the plum tree and replacing it with a variety that is less susceptible as there are varieties of fruit trees which are less prone to catching blight.
Note that the bacterium will overwinter in an infected plant. And in the spring it will be disbursed by rain, wind and insects. It cannot survive in the soil: there are no steps that you need to take to disinfect or replace it.
Good luck! With luck and good husbandry you should be able to preserve at least some of your orchard.