Apple Scab

Host

Apple scab affects apple trees.

Description Apple Scab

  • This fungal disease causes olive-green to black spots on the fruit and leaves. When the leaves are infected they become dwarfed, curled and drop prematurely. This leaf loss, especially when it happens over many seasons, can significantly weaken the tree. If the fruits get infected in the early season, they can get deformed and drop early in June. Moreover you usually can’t eat scabby fruits.
apple scab red apple

Causes

  • During the winter, apple scab can survive in the dead apple leaves on the ground. Then in the spring, these fungi shoot spores into the air which the wind carries to the growing leaves, flowers, and fruit. In order to start new infections, the spores have to have a couple hours of moisture. Afterwards, the infections grow into spots which produce more spores.

Treatment and Management

  • Firstly, you can choose scab resistant varieties such as Freedom, Liberty, Prima, Jonafree, GoldRush, and MacFree.
  • Secondly, remove fallen leaves from under the tree. If you control in the early season it will be much easier to control in the summer.
  • Sprays can help control apple scab. Some effective organic sprays include
    • Liquid copper soap: You can apply two weeks before symptoms normally appear or when symptoms first appear and repeat at 7 to 10 day intervals up to blossom drop.
    • Bonide® Sulfur Plant Fungicide, a finely ground wettable powder, is used in pre-blossom applications and must go on before rainy or spore discharge periods.
    • Organocide® Plant Doctor is an earth-friendly systemic fungicide that works its way through the entire plant to combat a large number of diseases on ornamentals, turf, fruit and more.
Knowing about apple scab will help you grow healthy apple trees. If you would like to discover our fruit trees, explore our fruit tree catalog or shop page.

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