Crabapple in trouble

Asked June 14, 2016, 2:06 PM EDT

Can you help identify this white material that has appeared on our previously healthy crabapple tree? This appeared almost overnight and now the tree overall looks extremely distressed. Any help or treatment ideas would be greatly appreciated. Thanks for you terrific resource!

Denver County Colorado

1 Response

From the photos you attached, it looks like your crabapple is suffering from fire blight. The Denver area has experienced severe bouts of fire blight the past couple of seasons. Fire blight is a bacterial disease that overwinters in cankers on the branches and trunk of the tree. The severity of fire blight varies from year to year depending on spring time conditions. The symptoms often seem to appear suddenly. There is no cure for fire blight. Management of the disease involves minimizing rapid new tree growth, pruning out infected branches and chemical sprays. I am attaching CSU Extension Fact Sheet 2.907 which discusses fire blight in more detail.