Elm Tree Honeydew Deluge: Aphid/Scale Infestation Solution

24-year-old elms on boulevard suddenly producing fine sticky mist covering cars, grass, railings. Gummed up mower. Never happened before.

Cause: Aphids or Scale Insects

Both suck plant juices, secrete honeydew (sticky, sugary). Aphids: small, slow, sometimes white-fluffy. Scale: immobile, armored on twigs. "Raining" sap is the nuisance.

Treatment Options

• Foliar spray: Difficult on large trees. Contact insecticides: Orthene, Talstar, Dursban, diazinon, malathion, pyrethrum, etc. Rotate if resistance suspected.
• Systemic soil application (recommended): Imidacloprid (Bayer Advanced Garden Tree & Shrub Insect Control) — applied to soil, transported to leaves/twigs, lasts months. Less harmful to beneficials.

Link: Product info