What to do about apple scab A few questions need.
Jul 25, Common Crabapple Diseases That Cause Summer Defoliation APPLE SCAB. If there's one crabapple problem that most people have seen or experienced with their own trees, it's apple Fireblight. This disease is more damaging to crabapples than apple scab as it can kill multiple branches and even the Estimated Reading Time: 7 mins. 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.
As the fungus grows in the developing leaves, it causes purplish-brown spots, often. 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. The latter, however, is.