Question
We have lived in KC for 11 years in what used to be a black walnut grove. The black walnut that hangs over our deck has produced shiny sticky stuff for the first time this year. We can't even sit in our chairs without our shirts becoming stuck to the back of the chair. What is this? We don't see any pests on the tree and the stuff covers everything.

Answer
This is a substance called honeydew. An insect called aphids or maybe scales suck the plant juices from the leaves and twigs and excrete honeydew. Honeydew is high in sugar content and normally a black sooty fungus will grow on honeydew. Control the aphids and the sticky will stop.  To do this the foliage will have to be sprayed with an insecticide.

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),
Check with your local nursery and ask for an insecticide for aphids on trees.