How to Identify and Manage Apple Scab Fungus

12.08.2024 - 17:15 / gardenerspath.com / Kristine Lofgren

How to Identify and Manage Apple Scab Fungus Venturia inaequalis

Apple maggots are irritating and powdery mildew is a pain, but when it comes to apple tree problems, scab is a big deal.

This disease costs commercial growers millions of dollars in damage every year and home growers endless heartache. In addition to apples, it devastates native crabapples as well.

Anywhere apples grow, scab is sure to be present, and while it isn’t a huge problem in hot regions, those growing in cool, moist climates might be in serious trouble.

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Even though this disease can be quite devastating, don’t give up on your dreams of growing apples or run for the chainsaw to take out your existing trees.

Since scab is such a big problem, experts have spent a lot of time figuring out how to deal with it, and there are some pretty good systems that you can implement.

We’ll explain the ins and outs of identifying, preventing, and dealing with apple scab in this guide. Here’s what you can expect:

Apple scab is a fungal disease that attacks both apples and crabapples (Malus spp.).

Hawthorn (Crataegus spp.), mountain ash (Sorbus spp.), and cotoneaster (Cotoneaster spp.) can also be hosts.

The disease is caused by an ascomycete fungus called Venturia inaequalis, which has several different strains. Each strain is species-specific, so the strain that attacks mountain ash doesn’t infect apples.

The same strains infect both apples and crabapples, which are members of the same genus, Malus. And, cue the scary music, some of these strains have become resistant to fungicides.

Pear scab is caused by a different species of Ventur