Question
Hi - We live in High River and have been in our home for almost 24 years and have a phenomenon this year.  I park my car in a space up to the front of our house and we have elm trees on the swath between the sidewalk and the road.  I have had glops of amber colored droppings before but this year everything - my car, the grass, the railing to the house are covered with a fine mist like, sticky substance.  My car looks like someone sprayed it with glitter.  After being parked for a day or two I can't see out the back window and it's nearly as bad on the side windows.  It doesn't seem to quit and here we are at the end of July.  A couple of days ago my husband went out to cut the grass in front and it gummed up the mower.  He had to "wash" the grass by sprinkling before he could cut it it was so gummed up.  What's differnt this year?  We are baffled as this has never happened before.  Any thoughts?

Answer
The tree has a population of either aphids or scale insects. Both of these insects sunk the plant juices from the leaves or twigs and secrete a substance called honeydew. this is high in sugar content and is sticky. Aphids are small soft bodied insects that move slowly and sometimes are cover with white fluff like substance. Scales and insects that live in covering and do not move once attached to the twig. Both can weaken the tree but the "raining" down of the sap is the nuisance part.

You can either spray the tree's foliage or use a systemic insecticide on the soil beneath and the tree will absorb the insecticide through the roots and take the insecticide to the leaves and twigs. Spraying a large tree can be difficult.


Chemical Control - Contact Insecticides Numerous contact insecticides are registered for aphid control. Since aphids are often placed under considerable pesticide pressure in field crops and greenhouses, they may be resistant to certain categories of insecticides. Therefore, if you do not obtain reasonable control, consider rotation to another insecticide. Contact insecticides currently registered for aphid control include: acephate (Orthene),  bifenthrin (Talstar), chlorpyrifos (Dursban),  diazinon,  malathion, nicotine sulfate, pyrethrum, rotenone, resmethrin, and tetramethrin + sumithrin.

Chemical Control - Systemic Insecticides Several systemic insecticides are useful in aphid control. Aphids have sucking mouthparts and are thus very susceptible to pesticides located in the plant vascular system. Some of the systemic insecticides also have contact activity. Systemics injected or applied to the ground are less harmful to beneficial insects. Systemic insecticides include: acephate (Orthene)


Certain persistent insecticides that move systemically in the plant may provide control through the fall. Imidacloprid (Bayer Advanced Garden Tree and Shrub Insect Control) is a newly available systemic insecticide that can provide aphid and scale control on trees for several months following application to the soil.  

Since the tree sound large, I would use the Bayer product. it will take a week or so to take effect but it has a longer lasting effect. Here is a web link to this product. http://www.bayeradvanced.com/product/Tree-Shrub-Insect-Control/concentrate.html