What is this??

Asked September 17, 2018, 5:01 PM EDT

Hi, Our flowering tree seems to have black mold on its leaves and these pink pods on the branches. Can you identify? How do we treat?? Thanks!!

Oakland County Michigan trees and shrubs sustainable gardening and landscaping insect issues gardening

1 Response

Hello,

I think your tree is a magnolia tree. Those pink pods are magnolia scales and the black mold on the leaves and branches is sooty mold that colonizes the scales' excrement (called honeydew).

The magnolia scale, Neolecanium cornuparvum (Hemiptera: Coccidae), is largest scale insect found in the U.S. with adult female scales measuring a half of an inch or more. Like most soft scales, they have a transparent wax covering the body and they produce copious amounts of syrupy excrement, euphemistically referred to as honeydew. This honeydew becomes blackened when colonized by sooty mold fungi, which gives the plant an untidy appearance. The magnolia scale overwinters as first instar (newly born) nymphs on undersides of 1-2 year-old twigs. The first molt occurs the following spring around late-April to mid-May and the second in early to mid-June. The insect normally becomes a deep purple by this time. Severely infested trees, which normally have light green stems, appear enlarged and purple in color from large numbers of actively feeding scales. In mid-August, females produce living young (crawlers) which wander about for a little while before settling down on new twig growth. A single generation occurs each year.

Dormant oils (sometimes called horticultural oil or Ortho Volck Oil) applied before bud-break in early spring is very effective in controlling magnolia scale. Sprays containing cyfluthrin (sold as Bayer Advanced Vegetable & Garden Spray), bifenthrin (sold as Ortho Bug B Gon) or malathion applied in late August and early September when the crawlers are active is another effective control strategy.

Bayer Advanced Tree and Shrub Insect Killer (imidacloprid) applied in May provides outstanding control of magnolia scale. Imidacloprid soil drenches should be applied around the base of the trunk (within 6 to 12 inches where high concentrations of fine roots facilitate uptake) using a bucket or watering can. Any mulch that may be present was pulled back first to facilitate infiltration. A small earthen dike can prevent run off from sloped surfaces and concentrate infiltration near the trunk. The amount to apply is based either on plant height (for shrubs) or trunk diameter (for trees). Imidacloprid has very low vertebrate toxicity, however, like other neonicotinoid insecticides, imidacloprid is implicated as a possible cause honeybees decline.

Be sure to read and follow all the instructions and safety precautions found on the pesticide label before using any pesticide.

Howard