Magnolia Scale: It’s Not For Wimps

My house is super clean which can only mean one thing. I’m procrastinating.

The decorations are down and the house is back in order. The sun is shining. I’m all out of excuses.  It’s time to tackle the Magnolia Scale. Blech!!!

Adult Scale

Adult Scale (Red)

Last summer we discovered a severe scale infestation on our Tulip Magnolia.  It was everywhere!  I removed numerous branches, perhaps close to a third, since the infestation was so bad.  We ordered beneficial lacewing eggs, hoping they would finish off the rest.

Now that the tree is dormant, it’s easy to see what remains.  Though not nearly as bad as last year, dozens of red scales (the adult female) along with the immature male and female nymphs, cling to the young branches.

Scale Removal

Scale Removal

Today, with my bucket and gloves in hand, I spent an hour scraping off scale.  They’re easy to see (bright red) against the trunk, but I had to stand on a step stool to reach all of them.  After tossing them into a bucket, I went back with a warm, wet rag and wiped off the nymphs.

The overwintering nymphs are all over the tree!  There is no way I could get all of them, but I sure gave it a try.

Scale Nymphs

Scale Nymphs

After giving the tree one last look, I sealed the scale in a plastic bag for disposable, and soaked the bucket, rag and gloves in hot, soapy water.

Scale in a Bag

Scale in a Bag

I’ll check on the tree again tomorrow, and if the weather warms up, I might take a hose to the underside of the branches to remove some more.

Here’s what I’ve learned:

  • When purchasing a young Magnolia tree, check the inner branches first for infestation.  Apparently many of the trees have scale before you bring them home.
  • Prune judiciously.  Magnolias, especially mature ones, don’t handle heavy pruning.
  • Time your pruning appropriately.  I’ve read the best time to prune is late winter, early fall, after flowering and before new buds set.  Given those parameters, you really need to stay vigilant.


Garden Fail: Scale

Our purple tulip Magnolia has scale, an infestation as repulsive as it sounds. It’s equally harmful and can ultimately kill the tree if left unchecked. We’ve been researching organic solutions, preferring beneficial insects if possible.

From the reading I’ve done, the scale may have been present months ago.  Beautiful blossoms covered the Magnolia last spring, with no signs of the scale.  In late June, however, I noticed some damage to of the leaves of the inner tree and only then did I discover the scale.  We have all the tell-tale signs, now that I know what to look for:

  • Crusty bumps along the branches
  • Sticky leaves caused by scale excretions
  • Ants on the leaves.  They eat the sweet excretions and are known to defend the scale since they provide a food source.

Here are a few more details from the College of Agriculture Sciences at Penn State:

Magnolia scales are usually massed on the undersides of 1 and 2-year-old twigs, with heavy infestations completely encrusting branches. Other indicators of a scale infestation include reduced foliage and flower production, undersized leaves and twigs, and a black sooty mold on the foliage. After digesting the plant fluid, the scale excretes a clear sticky liquid called honeydew, which provides an ideal substrate for the black sooty mold fungus to develop. Magnolia scale infestations often go unnoticed until the leaves and twigs of the host plant turn black with sooty mold. The honeydew also provides a food source, attracting ants, bees, wasps and flies.

Healthy Magnolia Branch

Healthy Magnolia Branch

Scale Infestation on Magnolia Branch

Scale Infestation on Magnolia Branch

Ants eat the excreted Honeydew

Ants Eating the Excreted Honeydew

The more I read, the more discouraged I become. Even the less organic solutions are often ineffective.  I read an extensive article saying that Predatory Beetles worked well, only to learn they are no longer commercially available.  Aphytis melinus is another possibility, and probably our next, best option. Pruning away the worst of the branches seems like a good idea, too.  I would hate to have this spread to our larger magnolia just a few feet away.

Suggestions welcome!