ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Apple Scab: What Causes It and What Can Be Done About It?

Updated on October 1, 2018
Casey White profile image

Dorothy is a former newspaper reporter and the author of several books. Michael is a professional landscape/nature photographer.

Apples are my favorite fruit so it breaks my heart to see any of them ruined.  This "WAS" going to be a healthy snack but now it's garbage.
Apples are my favorite fruit so it breaks my heart to see any of them ruined. This "WAS" going to be a healthy snack but now it's garbage.
Isn't this more like it?  When you want to eat an apple, isn't this the one you want?
Isn't this more like it? When you want to eat an apple, isn't this the one you want?

People in Washington State Know Apples!

Living in Washington state, you learn a lot about apples, so here I am with another article on a fungus that can attack your apple trees. This time it is apple scab and it affects apple and crabapple trees. It is, in fact, the most prevalent apple disease in the world and coastal states are particularly vulnerable to it because the fungus grows quickly in wet climates.

Moist, cool weather causes this fungus to thrive, and guess what the conditions are in Washington state most of the time! Moist and cool is the name of the game here in this state.

Apple scab disease is caused by a fungus called Venturia inaequalis, and it overwinters on the dead apple leaves on the ground. According to sources here in the state, the fungus will infect fruit around the bloom after only five to six hours of wetness. The spores are carried by winds and quickly infect young flowers, fruit and foliage.

This is a Great Video Relating to Apple Scab Management

The Life Cycle of the Fungus That Causes Apple Scab

How to Recognize Apple Scab Disease

A few weeks after those spores are blown about in the wind, the signs of the fungus will begin with dark green to black patches on apple tree leaves. The patches will look like scabs or blisters on the upper leaf surface, and as the infection continues to grow, the spots will enlarge and often join, causing the entire leaf undersurface to be covered. Then, the leaves will become twisted with a "puckered" look and turn yellow. The infected leaves will most likely fall early and trees that are severely infected may lose all their leaves.

On the fruit, look for dark scab-like patches to appear that will ultimately develop a white rim, which will later disappear from around the velvety-like centers. After it disappears, the centers will sometimes become raised.

The result of apple scab is usually fruit that is smaller than normal and distorted. Often, the fruit will be cracked and will drop early. Those cracks in the fruit allow organisms into the apple that cause it to rot.

Apple scab disease on leaves.
Apple scab disease on leaves.

How to Manage Apple Scab Fungus

It is important to apply fungicides to your apple trees early during the most critical period from the breaking of cluster buds until the leaves are fully expanded. THOROUGHLY apply fungicide containing triforine, sulfur, lime sulfur or captan and follow the directions on the label completely.

What you are trying to do is keep the scabs from appearing, because once they do, there is no cure. If the scabs do appear, be sure to remove the scabby shoots and fruits and discard all fallen leaves. Although infected fruits are U G L Y, they sometimes can be used unless they are infected very early.

Infected crabapple leaves.
Infected crabapple leaves.

How to Prevent Apple Scab Fungus

Find out from your local cooperative extension service in your area which varieties of apple trees are resistant to this disease in your growing zone. If you live in a coastal area where it is cool and damp, you might want to try heirloom varieties, which can be scab resistant.

Always prune your trees to allow proper air circulation so that the amount of wet foliage is reduced. Always rake up and discard fallen leaves and fruit to keep the fungus from further spreading.

© 2012 Mike and Dorothy McKenney

Comments

    0 of 8192 characters used
    Post Comment

    • Casey White profile imageAUTHOR

      Mike and Dorothy McKenney 

      6 years ago from United States

      Thanks for the comments. Although the apples that are infected may be unsightly, they are perfectly safe to eat. I would just peel or cut away the scabs and enjoy what is left!

    • Sheepsquatch profile image

      Sheepsquatch 

      6 years ago from Springfield, MO

      Are the apples safe to eat if the tree has been infected?

    • mwilliams66 profile image

      mwilliams66 

      6 years ago from Left Coast, USA

      I landed on your hub through a hop. What a pleasant surprise. We have an apple tree in our yard that is clearly suffering from this apple ailment. I had no idea what it was and had planned to begin researching. I found your article to be very informative. Thank you for posting.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://hubpages.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)