Cottonwoods Make Me Crazy

A few weeks ago I saw an article titled Don’t Plant These Trees in Your Urban Yard. Before I’d even read it, I guessed one tree that would be on the list: the cottonwood (Populus sp.).

We have two cottonwoods in the backyard, and every year – spring in particular – I wonder what possessed the developers of our mid-70s neighbourhood to plant them. While I enjoy the shade they provide on those 30°+ summer days, it doesn’t offset the many things I dislike about this ubiquitous Prairie tree.

cottonwood 1936

From USDA-NRCS PLANTS Database. Provided by National Agricultural Library. Originally from US Forest Service. United States, NY, Geneva. 1936.

Cottonwoods are a moisture-loving tree, normally found on floodplains and riverbanks. They crave water – and will extend their root systems widely to find it. Our yard is crisscrossed with cottonwood roots – some 10-15 cm in diameter and just under the ground surface, others mere  tendrils working their way into the raised garden beds from the bottom up. They’ve stretched perilously close to the foundation of the house, at a corner where water used to collect. Once they find that moisture, they grow prolifically! In the 6 years we’ve lived here, our yard has become increasingly shaded and the veggie garden has not been impressed.

Cottonwoods growing along the Oldman River, southern Alberta (photo: S Boon)

Cottonwoods growing along the Oldman River, southern Alberta (photo: S Boon)

Cottonwoods have thick bark that was meant to protect them from prairie grass fires. They also produce a lot of debris. Windstorms (which we get a lot of down here) easily break small and medium branches out of the trees. In early spring we rake up piles of dead branches, only to be inundated again in late spring as the May/June rainstorms pummel new leafy branches out of the treetops. One of our trees is infested with hard, dark brown galls caused by mites. The round, knobby growths on almost every joint are reminiscent of the inflammation of rheumatoid arthritis. The dogs, however, love them, and there are so many to choose from all scattered around the yard.

poplar_budgall_mite2

Mite gall on poplar; Photo from County of Vermilion River

When the warmth of spring arrives, the cottonwood buds open and exude a substance stickier than superglue, complete with a bright yellow resin. These sticky buds carpet the lawn (and the dogs, the soles of your shoes, the deck…), leaving a nasty stain in their wake. If you have arthritis, you can make ‘Balm of Gilead’ from the ripe buds – a cooked mix of olive oil and yellow resin to be rubbed into the joints.

Cottonwoods also produce a rooting hormone called auxin, meant to help them colonize new locations via wind or water-borne branches, or where the roots have extended some distance from the main tree. Cottonwood suckers pop up throughout our lawn and in the perennial beds, trying desperately to create a cottonwood grove. Catkin buds fallen from the tree try to root in the gravel around the raised garden beds, looking in vain for some decent soil.

Although cottonwoods make terrible neighbours in suburbia, they are a key species in their native floodplain habitat.

Cottonwoods are like the building blocks of mature floodplains, and are a key component of primary succession in these landscapes. Cottonwood establishment anchors floodplain sediments and can affect river flow paths by reducing the erodibility of the river banks. They’re also well-suited to environments that flood periodically – rather than being wiped out by a natural disaster, they thrive and keep the disaster from worsening by maintaining floodplain stability.

The trouble is, changes in river flow due to dam-related regulation and withdrawal uses such as irrigation has left cottonwood communities in a precarious position along many river systems. A comprehensive approach to water management that includes the water needs of riparian vegetation and aquatic organisms will be important in maintaining and restoring cottonwoods in the floodplain (not suburban!) landscape where they belong.

So out with the cottonwoods – at least in the backyard. Let’s make sure they thrive where they belong – along the river.

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7 thoughts on “Cottonwoods Make Me Crazy

  1. Pingback: Morsels for the mind – 14/6/2013 › Six Incredible Things Before Breakfast

  2. hoe can I get rid of cotton wood galls all over my front yard? Will removing the tree make them disolve? I have sprayed the new sprouts with 2-4-D many times and a new sprout comes up next to it almost immediately. Please help!

    • Glenda –
      the best way that I’ve found to get rid of galls is to rake them up.

      As for the new sprouts…these trees are hardy and not only is 2-4-D harmful to more than just sprouts (think kids, pets, beneficial plants), it’s not going to kill the sprouts. We’ve found that repeatedly cutting them off and/or severing the root they’re popping up from can help.

      You could take the tree down, which would get rid of the galls. But unless you get the stump ground out, and keep on cutting off the sprouts, it can regenerate from the trunk/roots.

      Good luck!

  3. I know this post is from 2013 but I’d like to know if you have any idea how long the sticky buds last? There is an enormous cottonwood tree in the yard next door and my deck, table, chairs, grill and my poor dog’s paws are covered. They are horrible. I’m losing my mind! I think my poor dog has sore paws from us picking them off when she comes in.

    • How long they last depends on the weather. If it gets cool and rainy they can decompose faster (and be less sticky). But if it stays hot, they tend to stick around (no pun intended) for over a month. My dogs can sympathize with yours!

  4. We live in sedona, az, and have a flood area that runs through our development. The flood channel goes through a golf course that is surrounded by town homes. We have a number of large cottonwood along the banks of the flood channel. Many of our neighbors want all the trees cut down because they claim their seeds are a nuisance. Others believe they are essential to the ecosystem. We heard a comment that we could cut down the trees and the roots will continue to hold the banks in check. Based on my reading, this will just result on new trees sprouting. Can you provide resources on these last two issues?

    • Cottonwoods are a natural part of the ecosystem, and play an important role in stabilizing the floodplain. You’re correct in noting that, if you cut them down without removing the roots, you’ll just get new trees sprouting. But you wouldn’t want to remove the roots because that will destabilize the stream banks.

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