Posted April 11, 2023 by Dr. Wei Z
When a new tree is planted, people pay attention to its above-ground part much more than the under-ground part. How does a new tree establish itself in a new environment? It is all about the underground part. Root establishment means tree establishment.
When we first started, we recommended TreeDiaper treemats be roughly double the rootball's diameter. The problem was most people don't know their rootball sizes. When we ask people the rootball sizes, they would respond with the caliper or container sizes. So we did a survey and find the most common caliper-to-rootball ratios. Then we changed our recommendation to accommodate it.
Recently, there is a trend of changes in caliper-to-rootball ratio. So we now change back to recommendations ONLY based on rootball sizes. And we developed a tool on our website for people to use.
Why do people change the rootball sizes relative to the calipers and why we are not changing the recommendations accordingly? Below is the long story.
Before the pandemic, we found there were too many have rootball sizes much smaller than the recommended minimum size in ANSI Standard for Nursery Stock (ANSI Z60.1-2004). They are substandard and should be rejected. Whenever we learned the rootball sizes are way too small compared to their caliper sizes, we tell them their best interest is to reject those trees! Because not many people do that, the nursery industry believes it is acceptable!
Since the pandemic started (actually the trend started before the pandemic and the pandemic speeded it up), the situation has gotten better. Don't get me wrong, there are still too many substandard trees. Ironically, it is not because the nursery industry suddenly likes to comply with the ANSI standards. It is because of the nursery stock shortage. The trees are sold earlier and they dig up the trees earlier with the same tools/wire baskets. So these trees get relatively bigger rootballs for their calipers compared to before.
It is a good thing. Our 2018-modified recommendation of TreeDiaper sizes should be changed accordingly. However, I am afraid it will go back to the old normal (substandard) as soon as the supply-demand relationship changes. Instead of going back and forth to chase the trend of changes, we will change it back to old original recommendations based solely on rootball sizes.
- Luke McCall, Former Arborist in City of Richmond, Virginia