What To Do About The Messy Cottonwood Trees?

Cotton, cotton, everywhere — cottonwood trees are very popular landscape trees, primarily because they grow quickly and reach heights of 80 feet or more. They also provide ample shade in hot Midwestern summers.

Cottonwood Seeds (EnLorax G. Edward Johnson | wikipedia.org)

Photo credit: EnLorax G. Edward Johnson (Own work) [(CC-BY-3.0) via Wikimedia Commons]

Cottonwoods are, however, known to be messy trees for a few reasons. In early June, the female trees drop “cotton” everywhere. The cotton is actually a seedpod, but looks like masses of fluffy cotton. Both male and female cottonwood trees easily drop small twigs and branches during windstorms. The trees also drop very sticky bud capsules that attach themselves to everything — including your dog’s fur and your own bare feet, and are difficult to remove – leaving a yellow stain behind.

Spray the Trees

It is possible to spray the trees or have them sprayed by a certified arborist if you don’t feel competent enough to do it on your own. You will need to use a product called a fruit eliminator. A fruit eliminator is applied to the fruit-bearing part of the tree, and fruit production is drastically reduced or eliminated. Such products are to be applied directly to the buds. The amount of cotton a treated tree produces will be much lower than that of an untreated tree.

Use a growth hormone or regulator to minimize the flowers that are produced and therefore the seeds. There are many on the market, but the product that works the most consistently has ethephon as the main ingredient. Apply the product in early spring.

Cottonwood Trees (gfpeck | foter.com)

Tall cottonwood trees. Photo credit: gfpeck | Foter.com | CC BY-ND

Set up a ladder so you can reach all the aspects of the tree. Mix the recommended amount of growth regulator for your tree size into the hose end sprayer. The usual amount for an ornamental tree is 1 quart chemical to 10 gallons water. Only mix as much as you will use and then screw the unit onto the hose. Turn on the water.

Spray the top of the tree first and coat the leaves and stems. Only apply enough to wet, but not cause significant chemical run-off. The best temperatures in which to apply the chemical are between 61º and 94º Fahrenheit. The chemical breaks down ethylene inside the tree, which is a hormone that signals flower formation.

Watch Out for Breakage

Another cottonwood problem that could be loosely classified as “messy” is that the tree tends to have weak, brittle wood. You can see this in the small branches and twigs that are sacrificed during windstorms. Because the tree grows so fast, its wood is not as strong as that of other trees. If you decide to leave the trees and treat the mess, and not cut down the trees, it is a good idea to have mature cottonwood trees examined every few years by a certified arborist to prevent catastrophic breakage – especially if the tree grows near your house.


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