Apple Scab in Illinois
MODERATEFungus
Apple Scab is currently active in Illinois. Watch your susceptible trees closely and act early.
About Apple Scab
The most economically important disease of apples worldwide. The fungus overwinters in fallen leaf litter and releases spores during spring rains. Severe infections reduce fruit quality and yield and can defoliate trees by mid-summer.
Symptoms to watch for
Olive-green to brown velvety spots on leaves, dark scabby lesions on fruit surface, leaf yellowing and premature drop, cracked and deformed fruit in severe infections
Trees at risk in Illinois
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Treatment options
Fungicide Spray Program
Captan or myclobutanil applied from green tip through second cover, with timing adjusted based on rain events and Mills table infection periods. The primary commercial control method.
Sanitation and Resistant Cultivars
Removal or chopping of fallen leaf litter in autumn to reduce spring inoculum, combined with planting scab-resistant cultivars like 'Liberty', 'Enterprise', or 'Pristine'.
Recommended Products & Tools
Helpful supplies for managing Apple Scab. Always read and follow label directions, and confirm a diagnosis before treating.
Broad-spectrum protectant for many fungal leaf and bark diseases.
Preventive spray for needle cast, leaf spots, and blights.
Sharp, clean cuts to remove affected wood — a tree-care essential.
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Need help with Apple Scab in Illinois?
Find certified tree care professionals near you.
Browse all Illinois arborists →Frequently asked questions
Is Apple Scab in Illinois?
Apple Scab is currently active in Illinois. Watch your susceptible trees closely and act early.
What does Apple Scab look like?
Olive-green to brown velvety spots on leaves, dark scabby lesions on fruit surface, leaf yellowing and premature drop, cracked and deformed fruit in severe infections
What trees does Apple Scab affect in Illinois?
It affects Pear, Apple. Susceptibility varies by species.
How do I treat Apple Scab?
Options include: Fungicide Spray Program, Sanitation and Resistant Cultivars. Confirm the diagnosis before treating, and consider a certified arborist for high-value trees.