Most scales are a bother earlier in the summer and Magnolia scale later in August. This year, call's started coming in mid -June, well ahead of normal. Calls were not always about the scale in the beginning, rather "What is all this black stuff all over everything?"
As the young scale crawlers begin to feed on the plant juices, much of it passes through their bodies and onto surfaces below. That sticky exudate is a great growth media for sooty mold, the black material covering foliage, lawn ornaments, the grill, sidewalks and driveways, not to mention the car parked under the canopy on the driveway.
Magnolia scale has very likely been living quietly and peacefully on the Magnolia tree for a long time, going unnoticed or creating minimal sooty mold below. In order to have such a large population this year, conditions last year were perfect, allowing large numbers of female scales to overwinter to produce the all the crawlers this year.
While the sooty mold is not desirable on plants below and other belongings, it is worse for the Magnolia as it can completely cover the upper sides of the foliage, greatly reducing the plants ability to produce photosynthates. Additionally, the crawlers are removing the liquids from the plant as well. The Magnolia will not overwinter as well as it should, may not produce the blooms for next year and even suffer dieback from winter cold weather. With these heavy infestation, losing interior foliage and limbs is a strong possibility.
With the abundance of crawler scales there should also be a strong increase in the number of natural predators feeding on the crawlers. The Twice Spotted lady beetle and other lady beetle larvae stages eat well. If predators are present, control options are limited to insecticidal soap. If management is going to include pesticides, the label will need to list both the insect to be sprayed. Like other scale insects, dormant oil sprays are also effective in controlling overwintering female adult scales.To help the magnolias with the loss of sap, water now and keep watering until it is time to remove the hose from the house for the winter.