I hope you took a stroll around the yard and did some pruning last weekend during the warm weather. If, at that time, you noted that some of the bark on your trees was damaged in some way, don’t panic. The best thing you can do is cut off any ragged ends or loose bark and leave the tree alone to heal itself.
This weekend, inventory your shrubs. Examine them first for disease and insects. One problem you might encounter, especially on euonymus and cotoneaster, is scale.
Armored scales are insects which are small, flattened, and disc-like. They live under a shell made from wax secretions and cast skins of earlier growth stages. (Remember, insects advance through several developmental stages or, molts, on the way to becoming adults. Molting involves shedding of the insect’s hard, outer exoskeleton. Stages between molts are referred to as instars, and each instar varies in appearance and size.). Scale insects settle onto stems to suck sap. If you can a scrap armored ovals off your branches with a fingernail, you know you have scale.
Most armored scales feed on trees and shrubs, but you can also find them encrusting the stems and leaves of houseplants.
Dealing with these pests on your shrubs is handled in a couple of ways. You can prune your shrubs back a bit in order to remove the most infected parts. To prevent further spread, burn these stems or soak them in a Clorox solution. Then, spray the shrub with an application of “dormant oil”. This can be done as early as March if it is above 40º F outside. Dormant oil smothers the scale insects. The warmth of spring will motivate the critters to crawl around which means they will spread. This is when you hit them with “horticultural oil”. Be sure to spray under the leaves and branches as well as from the top and sides. You can use the horticultural oil as a dormant oil as well. Check your local nursery or Wal-Mart for these sprays and follow the directions.