If your apples are developing soft, rotten spots and falling from the tree before they're even due to be ripe, chances are good that your tree is suffering from a fungal infection known as brown rot. This disease is more common in peaches, cherries and plums, but occasionally, it does affect apples in the United States. Here's what you need to know about treating and managing the condition.

What causes brown rot on apple trees?

Brown rot is caused by a fungus called Mononilia fructicola. This fungus prefers to live on stone fruit trees, but if your apple trees are near stone fruit trees that are infected with the fungus, your apples may become infected when the fungal spores enter the fruit through breaks in the skin.

How do you treat an apple tree with brown rot?

Once your fruit has developed brown rot and is beginning to fall, there is nothing you can do to save the afflicted apples. You'll likely lose most or all of your crop. However, you can take action to protect the next year's crop. The most important thing to do is to have your apple trees sprayed with fungicides. Captan is the most commonly used fungicide for apple trees, as it stays on the surface of the apples and has a low toxicity at normal use levels. It should be sprayed on your tree beginning in the spring as soon as the flower petals have fallen from the tree, and re-applied in 10-day intervals through May, followed by 14-day intervals until August.

There are a number of sprays that can be used instead of captan. These include dilute copper sprays and sulfur products. Your tree care expert can instruct you on the proper use of these products, depending on the variety of apples you're growing and your climate.

You can also help prevent re-infection the following spring by cleaning up all fallen fruits from the ground around your apple trees. Ensure you clean up fallen fruits from any nearby stone fruit trees as well, as the fungus will survive over the winter in these fruits.

How can you prevent brown rot from infecting other trees?

In addition to spraying the non-affected trees in the spring and throughout the growing season, you can reduce their risk of developing brown rot by having them pruned properly. This will increase airflow between the branches, so they do not remain as wet after a rainfall. If any of your neighbors have stone fruit trees that are suffering from brown rot, encourage them to have those trees treated with fungicides and to clean up their fallen fruit. This way, you'll eliminate the fungus at the source and protect your apple trees.

To learn more, contact a tree service company like L & M Tree Services.