Crabapple trees, when fully vibrant, can add color and shade to any landscape. A crabapple tree will produce small apples from their blooms. The one problem with crabapple trees is their susceptibility to disease and pests. There are a variety of issues that can kill a crabapple tree. Knowing some of the signs of a dying crabapple will help identify the problem and may offer solutions.
Look for color changes in the leaves; crab apple trees do not change leaf color during cooler months like maple or oak. Check for yellowing or brown spotted leaves. These can indicate the start of a pest infestation or disease. Leaves will change appearance and then drop off; usually the twig or branch it was attached to will begin to die as well.
Branch and Trunk Signs
Look around the branches and the trunk for open wounds in the bark such as cuts, cracks, scars or missing sections of bark. Check for insects that can disrupt sap flow, mushroom-like bodies or fungal crowns or domes that are signs of infections, and oozing sap that indicates the tree is losing the ability to get nutrition.
Observe the amount of blooms on older crabapple trees. Look for less flowering or for the tree to leaf-out (grow leaves only). Look for the tree to have flowers at odd times or repeated blossoms in one season. This is the final effort of the tree to produce seeds that may result in future offspring.
Check for yellow or brown lesions on the surface of infected leaves. Watch for leaves to start falling prematurely, as early as May. Observe disfigured fruit and take notice if that is the same area where leaves were discolored or falling. Apple scab is a fungus caused by wind-swept spores from another tree.
Notice if the apple blossoms are turning brown and wilting. Look for the twigs they are on to start wilting, shrivel and turn black. If you see the ends of twigs curling up this is a sure sign of fire blight on the crabapple tree. Look for an oozing discharge of translucent amber or red color; this means there is a severe case of fire blight. There is no cure for fire blight; but it can be slowed or halted by cutting off the infected twigs or branches at their base. Burn the infected cuttings to stop the bacteria from spreading further.
Spot wetwood by looking for cankers, slimy ooze from the base of branches, or signs of rotting such as soft wood or bark. Wetwood is a bacterial infection that rots crabapple trees from the inside out. This bacteria enters the tree via insect holes. Remove the entire tree from the area to salvage any other trees nearby; destroy the entire tree.