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Crabapple Tree Fungus

crab apple blossom image by Shirley Hirst from

While the ornamental crabapple tree is a common landscaping choice for homeowners, it is not unusual for trees to fall prey to an array of diseases and pests. Fungus problems are especially difficult to get rid of, but fortunately there are several things a homeowner can do to prevent and control damage to crabapple trees.

Types of Fungus

There are many types of mold that cause fungus problems for crabapple trees. Scab, also known as venturia inaequalis, is a type of fungus that attacks crabapple trees with a vengeance. Scab lives on the leaves throughout winter and begins to grow in the spring. It causes leaves to drop and inhibits the trees from thriving. Another mold that attacks crabapple trees is cedar-apple rust, or gymnosporangium juniperi-virginianae, which turns leaves yellow, causes black specks on leaves, and sometimes grows as orange spores on the undersides of the leaves. Consult a garden manual for a list of other fungus.

Disease-Resistant Trees

One way to fight back against fungus and mold problems in crabapple trees is to plant disease-resistant varieties. If you are considering adding a crabapple tree to your landscape, you will want to do some some research to find the best disease-resistant varieties before time to plant your trees. There are several disease-resistant crabapple trees to choose from, but among them are Autumn White, Autumn Glory, Coral Cascade, Donald, Gibbs' Golden Gage, Golden Gem, Molten Lava, Mt. Arbor Special, Prof. Sprenger, and sargentii 'Tina'. All of these types vary in appearance.

Common Fungus Preventions

Fungus and other disease problems in existing crabapple trees can be controlled with a variety of products. Fungicide applications and specially formulated oil sprays can be purchased and sprayed on trees prior to fruit development to prevent fungus from getting started. Timing of application is important and the entire tree must be sprayed until damp. It is highly recommended that homeowners and gardeners consult a manual and product instructions for proper amounts to apply and when to spray.

Organic Control

For some gardeners, the desirable way to fight fungus in crabapple trees is to use organic methods that are safe for humans and the environment. Planting disease-resistant varieties of crabapple trees is an organic way to prevent fungus problems. Another is pruning trees to remove dead branches and infected foliage. Gathering infected leaves and fruit that have dropped from the tree in a timely manner and disposing of them away from the growing area is another organic way to control fungus in trees that have already been affected.

General Care

General proper care of crabapple trees will go a long way in prevention of most fungus varieties and everyday diseases. Crabapple trees can still grow well in spite of the diseases that attack them, but it's a good idea to practice good pruning techniques and to water crabapple trees adequately. Proper fertilizing will also make crabapple trees stronger and less prone to fungus and disease. Consult a garden manual for the best fertilizer and choose one that is not high in nitrogen.

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