Key Features
- Sticky leaves
- Black sooty mold on leaves and stems
- Orange and brown bumps on twigs
Symptoms
Trees infested with tuliptree scales have twigs crusted with large, orange-brown female scales up to 3/8" in diameter. Scales produce a sticky excrement called honeydew than can coat leaves and branches, turning them black with an unsightly sooty mold. Honeydew begins to accumulate significantly after females mate with males in mid-June and continues throughout the summer and may cause a nuisance by attracting stinging wasps. Heavy accumulations of honeydew and sooty mold can kill branches. All stages of this scale can be separated from the plant tissue by flipping them over with a fingernail. This flipping process will not rip the plant surface. If you remove a bump on a plant and the tissue rips, this means the plant has produced a gall or swelling in response to an insect or disease and is not a scale insect. On tulip-poplars the honeydew from aphids can cause similar problems, so be sure to compare the what you see with the Pest Detail for aphids. Similarly, on magnolias, be sure to compare with the Pest Detail for magnolia scale because its honeydew can cause similar problems.
Biology
Wintering as immature scales on twigs, they resume feeding when the plant comes out of dormancy in the spring. Winged males emerge in June and mate with females. Females can produce over 3,000 eggs that hatch into black crawlers in late August and September. Crawlers migrate to and settle on stem. Immature scales winter on stems.
Management Recommendations
Insecticidal soap directed against crawlers in August and September can help reduce scale populations with minimal impact on beneficials. Pyriproxifen or buprofizen directed against crawler and recently settled scales can also help reduce scale populations with minimal impact on the beneficials. Other products listed will kill scale crawlers and beneficial insects Applications of oil in the dormant season will NOT kill this pest. We do not recommend the use of soil applied insecticides for this pest because tuliptree flowers are an important resources for many pollinators.
Effective Pesticides
Active Ingredients include: Acetamiprid, Azadirachtin, Bifenthrin, Buprofezin , Esfenvalerate, Flupyradifurone, Fluvalinate, Insecticidal soap (Potassium salt of fatty acid), Lambda- cyhalothrin, Pyriproxyfen
