Associated Insects

• Aphids are the primary honeydew-secreting insect associated with black sooty mold. There are other insects who also secrete honeydew, however. These include soft scales, mealybugs, whiteflies, leafhoppers, planthoppers and psyllids. On occasion, sooty mold can form if a tree above it is infested with honeydew-secreting insects and the honeydew drips onto the tree below or if a population of spittlebugs moves into the neighborhood.
  
  

Affected Trees

• Many trees are common hosts to insects that secrete honeydew. Shade trees such as maple, beech, ash, spruce, pine, poplar and oak are susceptible to infestation of these insects. Flowering trees aren't immune, though. Dogwood, crape myrtle, tuliptree and magnolia may also be affected by sooty mold. Sooty mold can form on any kind of fruit tree, from lemons to apples.
  
  

Cleaning Sooty Mold

• Sooty mold can be cleaned from trees with a pressurized water spray. Often, adding soap or detergent at a rate of 1 tsp. per gallon will help to dry the mold up. Test an inconspicuous spot a week before using soapy water all over the affected tree, as some are very sensitive to soap.
  
  

Controlling Mold

• The best way to control sooty mold is to destroy the insects that cause it. All sucking insects can be controlled with systemic insecticides, such as imidacloprid, which is applied to the roots of affected trees. Systemic insecticides work by being drawn into the plant's system and then entering a sucking insect when it pierces the plant. Systemics are highly effective and pose a minimal risk to non-target insects. Systemic insecticides effective on sucking insects include acephate, imidacloprid, and dinotefuran.