Warding Off Scales

Azalea Scale Infestation

Azalea bark scale (Acanthococcus azaleae) infestations can be severe. This sap-sucking scale can cause serious harm to your favorite Azalea or Rhododendron.

The adult females (1/8 inch) with their white egg sacs are most noticeable in May and June. Symptoms of their sucking include honeydew, sooty mold, and considerable leaf yellowing and die back. Infestations over several years can kill a shrub.

In addition to Rhododendrons and Azalea, this bark scale will also dine on other plants such as Andromeda, Arborvitae, Fremontia, Hackberry, Maple, Poplar and Willow, causing similar damage.

Native Cottony Maple scale (Pulvinaria innumerabilis) is another scale that attacks the phloem layer of the bark of other shrubs and trees. It has our attention particularly on Kousa Dogwoods. This scale is black (3/16 inch), and also is most noticeable in May and June when its cottony white ovisacs can litter bark and leaves. Heavy infestations may cause leaf yellowing, honeydew, stunting and die back. Cottony Maple scale can be found on plants such as Dogwood, Elm, Hawthorn, Linden, Poplar and Sycamore.

Because the nymphs for these scales live over winter in the forks and crevices of the shrub or tree, we use a dormant oil spray in early spring, and insecticidal soap, or summer oil, as needed, throughout the spring and summer to minimize the scale population. A soil injection of systemic insecticide in early spring almost always greatly reduces the scale population.

Our up-to-date certified arborists will inspect your landscape and recommend the best plant health care program for your shrubs and trees.

As the Leaves Turn


Autumn may be the most beautiful season in the Delaware Valley. The magnificent fall foliage is a natural phenomenon that one can’t help but admire. While you enjoy fall’s colors, keep in mind that winter is the ideal time to prune your large specimen trees.

After the leaves drop, you may notice a significant change in the branch structure. Your trees may have too much weight on the ends of the branches and need to be thinned to reduce the load on the limbs. Weight reduction is especially important for trees growing in full sun which have a large spread to their canopy.

After trees are pruned, a healing process, called compartmentalization, is responsible for closing the cuts, or wounds. Compartmentalization starts, and is most active, in the spring when trees return from dormancy and begin their new growth. Winter pruning allows pathogens the least amount of time to attack a wound in a tree.

Another reason to consider winter pruning is to save the understory trees and shrubs, garden plants and groundcovers from being damaged by falling limbs.

American Elms are only to be pruned in the winter because pruning during any other season is sure to entice the Elm Bark Beetle to attack the tree and kill it. Mature Sycamores, Maples, and Oaks are all perfect candidates for winter pruning as well.

As a general rule of thumb, each tree on your property should be pruned at least once every five years, so you should consider having twenty percent of your trees pruned each winter.

Call your arborist for a fall property inspection and analysis to determine which of your trees should be pruned this winter so they may flourish for years to come.


Why Fertilize Your Trees

McFarland’s Arborists generally recommend fertilizing trees in the fall. When discussing fertilization with our clients, we have found three questions reoccur. Here are those questions and our answers to them:

Q. Why is it necessary to fertilize my trees when it appears the ones growing in a forest environment seem healthy without it?

A. Trees growing in designed landscape settings are not the same as those growing in a forest. Leaves and debris that fall from forest trees remain there. Breakdown of these materials creates a less compact and more nutrient-rich soil that is rarely reproduced in the average yard.

Leaves in yards are usually raked up and hauled away. Ground covers (ivy, pachysandra, etc.) and grass (the worst of all) are in competition with tree roots. Therefore, your trees must work much harder to get the water, oxygen and nutrients they need.

When you walk through a forest, you may notice many trees which are dying. Typically, that is not a problem because other trees will fill in and replace those that die. However, in your yard which has a limited number of trees and space, losing even one tree can be devastating to your landscape.

Q. Doesn’t fertilizing just make my trees grow faster and therefore accelerate the need to prune?

A. If your trees are growing more, they are healthier. Using a slow-release fertilizer in the late Fall, we create a gradual breakdown of nutrients, encouraging root growth over the winter and some new growth the following Spring. This is the optimum method of fertilizing trees and comes closest to the way trees feed themselves in the forest.

In most cases, pruning trees more often is less expensive than removing and replacing them when they die. Who wants to wait 20 years for the new trees to grow?

Q. Will fertilizing burn trees already stressed due to this summer’s drought?

A. The fertilizers we use do not burn trees. They release Nitrogen and the other necessary nutrients slowly into the soil over the course of the entire year. In fact, the extended drought over recent years is another reason to fertilize. When trees are stressed due to drought, their roots die.

Fertilizing encourages root regeneration, helping trees cope with drought stress in the future. Stressed trees are more susceptible to insect and disease problems that are killing so many of our trees in the Philadelphia region.

Providing adequate nutrients keeps trees healthy longer, and helps them not to succumb to problems as they age.