A few weeks ago while on a site visit with my boss and I can across a really good example (or bad if you are the tree) of stem girdling roots on a Lanceleaf Cottonwood (Populus acuminata).
|Ingrown girdling root|
|The other side of the trunk|
Trees are often predisposed to forming girdling roots by poor planting practices or issues created in the nursery (More information on tree planting can be found here). Trees which are planted too deep are particularly prone to developing such roots. Some research has indicated this may be due to the development of advantages roots above the existing roots system. These new roots are prone to growing vertically through the soil or at odd angles rather than outward from the tree and are thus more likely to intersect the tree’s trunk. Repeatedly shifting nursery stock to larger containers or keeping the stock containerized too long may also hinder a tree from developing a normal root system and increase the chance of girdling roots forming. If potential girdling roots are not or cannot be addressed they can impend the flow of water and nutrients though the plant’s vascular tissue. At the least this can this lead to stress which contributes to the decline of a plant. At worse such roots can be the direct cause of a trees death.
|Symptoms of Girdling roots on |
I always find communicating these long term tree health issues to clients difficult. It seems like they are often at least somewhat incredulous that their 5 to 10 to 20 year old tree is struggling because of how it was planted. In this case this was definitely true. The clients had originally contacted us because they were worried about herbicide drift into their yard. They reported that they were regularly (several times a day at the same times of day for months) inundated by a strong odor which smelled like “An herbicide”. They had already had the gas utility come out and confirm there was not a natural gas leak and were sure that there was a toxic chemical drifting into their yard from somewhere. Daily repeated herbicide drift seemed unlikely but the situation was intriguing (A dead tree! Struggling plants! A powerful and strange smell!) so we set up the site visit and went to take a look. We were not treated to the offending odor or able to identify its source but suggested the clients consult with the health department if they were still concerned.
The stench must have been more compelling than our explanation of girdling roots because after explaining the issue the clients told us they were “Sure we were right…” but still remained convinced that someone was poisoning their yard. Though, they did agree that the girdling roots certainly looked bad….