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Crabapple Scab Disease: Dormant Oil Wrong Treatment

Crabapple (10-12 ft) flowered yearly, then reduced blooms, reddish leaves, black spots, heavy drop. Home Depot recommended dormant oil. Two spring applications—still poor flowering, lower branches leafless, rust spots appearing.

Likely Apple Scab (Venturia)

Fungus causes early leaf drop. Dormant oil ineffective. Correct timing: spray at first leaf emergence from buds in spring. Rake/destroy ALL fallen leaves BEFORE spring bud swell—fungus overwinters on them.

Better Products

Bonide Infuse or Hi-Yield Captan (not big-box stores). Need sprayer covering ENTIRE tree. Get soil test. Water/fertilize for vigor. Take leaves to local garden center for confirmation.

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