This fungus overwinters on dead leaves that fall to the ground.

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. Aug 26, Spring weather that is humid and warm - 60 to 70 degrees - favors its growth.

Fungus spores live on infected (fallen) leaves over winter and in the spring, Estimated Reading Time: 3 mins. Jul 25, Crabapples are beautiful trees that grow well in the Dayton, OH area. However, many are susceptible to a number of crabapple diseases that cause them to drop leaves and generally look unhealthy by the end of summer. If your crabapple has wilted and blackened leaves, dead or orange spots on the leaves, or strange orange growths, it’s likely caused by one of the three most common crabapple diseases Estimated Reading Time: 7 mins.

Feb 26, In midsummer, the leaves turn yellow and drop, leaving an unsightly skeleton of a once-lovely tree.

Apple scab is widespread and first presents as yellow, then olive-green spots on the leaves and darker, slightly-raised spots on the fruit.

If your tree is susceptible to scab, it will need preventive fungicide sprays in future years. For best results, begin spraying in early spring just before the flowers bloom and the leaves unfurl.