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Scale infestation on a mature Tulip tree #829525

Asked May 11, 2023, 2:50 PM EDT

Hi, We purchased a house in the winter in Fuquay and were so excited to have a mature tulip tree. It looks pretty healthy and had healthy full blooms this spring. It was planted at the corner of our deck so it provides canopy over part of the deck. Unfortunately, we have discovered it is heavily infested with scale, so much so that it looks and feels like it is raining when under the tree on the deck. I’ve read the state publications on control measures, and have outlines a plan for spring and fall, but am curious how long the control measures might take to rid the scale. We can’t use half of our deck which means the furniture can’t be out because we (and the furniture) are getting soaked in the sticky honeydew! Is it practical to think we can control this within a year or will this tulip tree need to be cut down? Thanks!

Wake County North Carolina

Expert Response

You should be able to make a good dent in the scale population within a year.  The key is treatment at the right time and vigilance.  If you are planning to kill the crawlers with horticultural oil, you have to be vigilant with monitoring and treat the scale at the right time.  Sometimes repeat applications are necessary to make sure you get all the insects.  If you have a large infestation, it can take over a year to get rid of the scale completely.

Here is some information on scale and tuliptree scale.  A suggested non-chemical method of removal is a strong spray of water and a soft brush to dislodge the scale.  That's not something I'd want to do though.

Introduction to Scale Insects | University of Maryland Extension (umd.edu)

Tuliptree Scale | Entomology (uky.edu)

If you have additional questions, please contact us.

An Ask Extension Expert Replied May 11, 2023, 4:52 PM EDT
Thank you for your reply! This tree is way too large at about 25 feet tall to hand scrub the ends of the branches to manually remove the scale. I had a maple tree one time where the scale was primarily on the main trunk and lower branches and I was able to pressure wash them off, but this tree is mainly affected on the exterior branches. I know it’s not ideal time, but could I take our pole saw and trim the tree to at least physically remove a large portion of the scales to stop so much phloem from dripping all over our deck furniture? 

As for horticulture oil, how do I ensure a tree this large is fully covered on all surfaces without also creating a huge mess since the tree hangs over our deck? 

Lastly, if we decide to replace the tree, should I have an arborist out to assess before doing so? And if we replace, could you recommend a fast growing tree that reaches no more than 20-30ft tall that could be planted at this back corner about 10ft from the house? 

Thank you!
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On May 11, 2023, at 4:52 PM, Ask Extension <<personal data hidden>> wrote:


The Question Asker Replied May 14, 2023, 3:23 PM EDT

Since your tree is 25 ft tall, you should consider a systemic herbicide instead of spraying.  It would be difficult to spray the entire tree to try to get all the scale insects.  I don't know what variety of tulip poplar you have but a mature tree can reach over 100 ft. in height.  Since your tree is 25 ft tall and blooms, it may be a smaller cultivar or the previous owners pruned the tree.  You might consider planting another tree as tulip poplars can be weak-limbed and break easily.  And tulip poplars are prone to scale and aphids. 

Here is some information on tulip poplars.  On the left-hand side of the screen are suggestions for substitutes for tulip poplars.  In general, it's best to stay away from fast-growing trees as they tend to be weak-limbed and prone to breakage.

Liriodendron tulipifera (Canary Whitehood, Canoewood, Lyre Tree, North American Whitewood, Tulip Poplar, Tulip Tree, Western Poplar, Whitewood, Yellow Poplar, Yellow-Poplar) | North Carolina Extension Gardener Plant Toolbox (ncsu.edu)

The Serviceberry tree is a nice native plant that grows to 25 ft tall.  It has flowers and berries.  However, I don't know if you want berries on your deck.  And it can develop a suckering habit and become weedy.  Here is a list of recommended native trees and plants from the North Carolina Native Plant Society.

Recommended Native Species - North Carolina Native Plant Society (ncwildflower.org)

If you want to keep your tulip poplar, you might want to have a certified arborist look at your tree to assess the health of the tree and perhaps do the hard work of pruning, spraying or applying a systemic herbicide.  You can find a certified arborist in our area at TreesAreGood.org.

An Ask Extension Expert Replied May 14, 2023, 4:48 PM EDT

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