It’s important once you’ve committed to your plum tree to be aware of the possible diseases you might encounter. Early recognition can stop your tree from becoming too badly diseased or infested with unwelcome insect pests.
Plum Tree Diseases
A diseased Plum Tree can result in reduced or unusable fruit yields. At worst, it may mean your fruit tree does not survive. Here’s the most common diseases that affect plum trees, and what you should look out for to identify them.
Silver leaf disease is an unusual, but very serious infection of fruit trees. It most commonly affects plum trees but also affects apples, cherries, and some shrubs.
Affected trees suffer from silvery leaves, with damage localised to specific areas of the tree rather than an all over silvering which can happen due to environmental stress factors.
Fungal infestations may also appear in these areas. The fungus has a distinctive white wooly texture on the upper arease, with purple colouring towards the bottom.
Avoiding winter pruning is key to prevention. To treat, prune away all affected branches.
Bacterial canker is another serious disease of plum trees and other trees from the prunus family. In spring and early summer, a diseased tree will develop oozing patches of bark which may be dead and sunken in appearance.
In summer, small holes appear in the plum tree leaves. They give rise to an additional infection, shothole, also known as Coryneum Blight which is caused by a fungal spores.
Branches can quickly die of bacterial canker. Avoiding winter pruning helps avoid canker infection. To treat, remove infected branches as quickly as possible and burn them to avoid reinfection.
This is easily identified by the growth of hollow fruit which will also be discoloured.
This plum tree disease will return every year if left untreated and will grossly affect your fruit production. You can treat this disease using an appropriate fungicide spray. Always be sure to follow the instructions.
This can be a little tricky to identify as brown rot often appears in the late stages of fruit growth. Brown patches will appear on the fruit and once established can take hold quickly.
Treatment needs to be a brown rot fungicide and any diseased fruit or branches must be removed immediately.
Most often transmitted via aphids, plum pox virus unfortunately has no treatment available.
It can be identified by discoloured rings on the leaves and fruit. Once infected, the tree should be removed to avoid the risk of further plants and trees from becoming infected.
Shot hole disease is also known as Coryneum Blight. It can look like insect damage because of the holes that develop in the leaves.
In serious cases, this infection can severely effect fruit production. It can be treated through the use of anti fungal sprays, and prevented through the practise of careful pruning and keeping a watchful eye on trees after very wet spells.
Common Plum Tree Insect Pests
Like most orchard plants, plum trees suffer from several insect pests which need careful monitoring and management:-
This type of insect makes the plums inedible once infected. On the outside the fruit looks fine but the insides show the damage caused by the sawfly.
These insects emerge from their eggs in the blossom during the spring months and make their way into the plum.
Plum Moths usually appear around fruit trees in May. If you see them then it’s likely some of your fruit will have succubmed to Pink Plum Maggot infestation (see below).
You can interrupt their lifecycle by placing plum moth traps around your fruit trees from May to August.
Pink plum maggots are the larval stage of the plum moth lifecycle. Sadly they will render the fruit inedible once they have infested it. Victoria plum trees can be more prone to these insects than the other varieties.
OK, so clearly not a creepy-crawly but pigeons can be a big pest in the world of plum trees. Pigeons will peck at the growing leaves and buds, often to the point where they won’t grow.
These are evident by looking for small green caterpillars. As they get bigger, they rely on the buds for their food sources, often destroying the fruit growth.
These insects are very distinctive in appearance, emerging as pea-sized lumps on the branches. They feed off the sap and can do a lot of damage if left untreated.
Plum trees are susceptible to aphids and this can be quite easily identified by a tell-tale curling of the leaves.
The damage that these aphids cause depends on the population of them, they can and do prevent optimum fruit growth.