Sep 05, 2471 Watertown MA leaves become curled and yellowish with lesions, eventually turning brown.
Heavy disease pressure leads to premature leaf drop. Fruit infected by apple scab develops raised scab-like lesions and severely infected fruit will drop from the tree. Crabapple varieties can vary greatly in their susceptibility to apple scab (Venturai inaequalis). What causes these attractive trees to drop their leaves mid-summer?
The answer is a fungal disease called apple scab. A fungus called Venturia inaequalis infects crabapple leaves early in the spring. Most people don't notice the disease, though, until these infected leaves turn yellow and fall off the tree.
Sep 21, A crabapple tree losing leaves early is indicative of disease. Two crabapple tree diseases in particular cause early defoliation: apple scab and cedar apple rust. Patrick Anderson talks about why apple and crabapple trees might be losing leaves in August. Patrick Anderson discusses why the leaves on people's crabapple trees are turning brown and falling off for this ask the arborist Ask the Arborist! Patrick Anderson discusses why the leaves on people's crabapple trees are turning brown and falling off for this ask.