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Plant Diseases/Object on Apple Leaf

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Question
Object on Apple Leaf
Object on Apple Leaf  
This object is on about 10% of trees in an apple orchard. Not sure what it is...possible fungus? It is not moving and does not seem to be an insect. What is it? Is it cause for concern? If so, what should be done?

Answer
Landon:

This may be a fungus disease called Cedar-Apple rust. One stage of the fungus is called the aecial stage. The fungus spends part of it's life on an apple and part on the cedar. Using your computer, look at some pictures of this disease on the apple portion.  The fungus produces a characteristic orange/red leaf spot on the apple seen from the topside of the leaf. On the underside of the spot, these hairy structures are seen. The leaf spots are about 1/4 inch in diameter and easy to see. If you do not see this orange colored spot, then this structure is probably an insect. If this situation does not seem to be causing an apparent problem with your tree, I wouldn't worry. There are usually many beneficial insects that keep the "bad guys" under control.

Steve

Plant Diseases

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Dr Stephen Vann

Expertise

Plant Diseases and Disorders of Lawn Grasses, Trees, Vegetables,and Ornamentals

Experience

Plant Diseases Identification and Management

Education/Credentials
B.S. Botany --- Miss. State Univ. M.S. Plant Pathology --- Miss. State Univ. Ph.D. Plant Pathology --- Texas A & M Univ.

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