Magnolia Scale Treatment – Timing is Everything

Our customers have noticed that we are starting treatment for Magnolia Scale later than usual this year. In the past, we generally the first application occurred in late September. We based our application timing on everything we had read and were told by leading entomologists who study the lifecycles of these insects.

‘Scale insects’ are very difficult to control in general but especially Magnolia Scale. Instead of going with the conventional wisdom for when to treat these trees in our temperate zone, we decided to get a little more scientific.

If you really want to know what our game plan is, and why, please read on.

The Life Cycle of Magnolia Scale

The white and grey pods that you see on the branches of trees were created by a single female Magnolia Scale adult. She formed that pod in the Spring, stayed inside it all Summer before giving birth to hundreds of baby crawlers. Once she gives birth, the female adult dies within the pod. These baby crawlers are almost microscopic when they hatch and live within the pod, feeding off of the carcass of the deceased female. (We know, kind of graphic). The crawlers will slowly begin to emerge from the pod late Summer through early Fall.


photo courtesy of Joe Boggs

This had us wondering; How long does it take for all of the crawlers to emerge from within the pod? A few days, a week or a month? Since the insecticide sprays will work best if we spray once ALL of the crawlers have emerged, this seemed like an important thing to know. None of the experts that we talked to seemed to know the answer to that question.

So, Tree Green purchased a powerful microscope of our own to see exactly what was going on with these crawlers first hand. We noticed that some of the crawlers were indeed out from their pods in August and we wondered if we actually needed to start spraying earlier than we had in prior years. Once we flaked some of the pods open however, you could see under the microscope that there were still more crawlers concealed beneath the pod. Then we re-checked every week and to our surprise there were still crawlers feeding within the pods.  Our most recent check was the other day, October 3rd. Granted there were fewer crawlers under the pods and had we sprayed, some would have been protected.

Photo: Rutgers Cooperative Extension

Photo: Rutgers Cooperative Extension

Once these crawlers emerge from the pods, we are told they do not go back inside. They live on the tree or travel to other area Magnolia trees. The crawlers go dormant when temperatures drop below freezing over the Winter. Once Spring comes, the baby females grow, mate and begin making those pods all over again, repeating the cycle.

We are waiting until our microscope tells us that most, if not all of the crawlers, have emerged. There are many factors that could influence emergence however. Certain neighborhoods may be affected differently from others and tree exposure to sun and shade is different from property to property.  We are doing our very best to monitor these insects and take into account these varying factors to choose the best time to begin spray applications.

Insect and disease control is not an exact science so one year might be different from the last. This year we might start in mid-October and next year, late September. The type of Spring, Summer and Fall that we have changes from year to year, and with that, so changes the cycle of living organisms.

We know of no other company who takes the measures that we do to ensure the best possible service delivered at the most opportune and effective times. We pride ourselves on that fact and thank you for continuing to trust Tree Green with your tree care!

Before and After Tree Treatment

We wanted to share some photos of before and after treatment.  We think you’ll agree they’re pretty remarkable. In the first two photos you see an absolutely enormous Ash tree. This tree is probably 200 years old, or older, with a trunk diameter just short of five feet across. It hangs over and shades the entire back of our customer’s house and stretches out over the back yard. The tree is spectacular and adds tremendous value to the property.

In 2013, we were contaash tree before eab treatmentcted by the owner of this tree, concerned about its obviously weakened condition from the Emerald Ash Borer, as shown in the first photo. You can see by looking at the trees in the background of the first photo, that this tree should have been fully foliated when this photo was taken, as those other trees were.

We gave this potential client a 30% chance, maybe less, of saving this tree but this tree owner said if there is any chance at all, he wanted to try.

ash tree after eab treatment

After 4 years of treatment, you can see how it looks today in the second photo.

Needless to say our client, and we, are thrilled over the result.


To date, we have saved over 94% of the Ash trees that we have set out to save. The only exceptions are trees where treatment was started later than would have been optimal or where there are horrible soil conditions such as too much clay or too wet of an area. These other stress factors, coupled with the constant onslaught that these trees are under from the Ash Borer, were just too much for those trees to overcome.


magnolia tree before treatment

magnolia tree after treatmentIn the second set of photos is a Magnolia tree. The first photo shows the tree in a very weakened, yellowing state. Yellow leaves occur when a tree is lacking necessary nutrients to keep its leaves green. This yellowing can be caused by insects sucking the nutrients out of the tree and/or poor soil conditions. Yellowing leaves are an indication that the tree only has a few years left to live if left ‘untreated’.

In the case of this tree both Magnolia Scale insects, as well as a small plot of soil in which to grow (sandwiched between the house foundation and a driveway), were the cause of its trouble back in 2011. In the second photo you can see the tree today, after six years of treatment. It is obviously thriving and its natural green color is back – thanks to a tremendous reduction in the scale insect problem and proper Root Fertilization.

Now, of the hundreds of Magnolia trees that we treat, we have a few trees in certain neighborhoods that are not responding as well to our treatments against the Magnolia Scale which is plaguing these trees all over our area. Scale insects, whether it is Magnolia, Lecanium, Cottony Maple or Euonymus Scale, are difficult to control. It often takes a few years to get the problem under satisfactory control. Why is this? Because Scale insects are masters at developing resistance to pesticides. The problem is that we don’t know which products they have learned to resist until we see the result the following year. Once we see that resistance might be an issue, we have to switch to different products to get control. Going forward, starting with treatments this coming Fall for this problem, we plan on rotating pesticides much more frequently.

Magnolia Scale Causing Damage

magnolia scale magnolia with white spots - scale

We realize that there are many different types of Scale insects, but by far Magnolia Scale is the most prevalent these days.

This year, we are getting inundated with phone calls from homeowners whose magnolias have Scale. Their trees are developing blackened branches and leaves, and the shrubs, perennials, concrete, decking and deck furniture under them are also turning into a black, sticky mess. A black fungus called ‘Sooty Mold’ develops and grows on anything the dripping sap lands on.

These insects are sucking the moisture and nutrients out of these trees; and left unchecked, this can result in the death of the tree.

This problem will only worsen year to year as the insects will mate this Fall and leave behind Scale offspring which will overwinter and spread heavier again next year.

Check the undersides of your Magnolias branches. If you spot this Scale, give us a call. We would be happy to stop at your home to inspect your trees and leave you more information regarding treatment and pricing.