Bryan from Polk City, IA
Thanks for your question about scab on your crabapple trees.

Crabapple scab is most prevalent when spring weather is mild and wet.  Crabapple scab is a disease caused by a fungus in which olive brown velvety spots 1/4 inch or more in diameter, appear on leaves, twigs and young fruit.  Severely infected trees may defoliate completely.  If your tree gets a case of scab, the best prevention is to remove and destroy leaf debris and infected fruit in the fall.  You can add an application of a fungicide like Earl May Fung-onil in the spring.  The best time to spray your crabapple is before or after it blooms.  Don’t spray during the blooming process or you will loose all your fruit, and it’s bad for the pollinators like bees.

Grow Your Own Way,
Gordon