Root ball problem receives national attention
Morton Arboretum in Chicago is coordinating an industry-wide working group formed to find solutions for tree decline and death in the landscape due to excessive amounts of soil over the root systems of field and container produced ornamentals.
The working group includes representatives from the American Nursery & Landscape Association, the International Society of Arboriculture, the American Society of Landscape Architects, the Associated Landscape Contractors of America, The Tree Care Industry Association and the American Society of Consulting Arborists.
Regardless of whether the liner is planted too deep, cultivation throws soil to the row. Erosion and a slope can also contribute. Several inches of soil could accumulate over several production years.
It may not be a management decision. Labor may do it when management is not looking, if it is easier. But some producers may do it to help the plant stand up and not be blown over. Others may put the roots where they think good moisture is. Some may try to hide a severe crook.
Landscape contractors and arborists have complained for years that transplanted B&B plants decline and die because of being grown too deep at the nursery. The root ball contains too few roots and none in the top few inches above the normal root flare. The industry is beginning to listen and it is beginning to be discussed openly.
Articles are appearing in national trade magazines. It is a topic at major nursery seminars. Dr. Appleton at Virginia Tech had an interesting article on root depth in the November 2001 issue of Nursery Management & Production magazine.
The American Nurseryman magazine had an article about the problem a few
years earlier, which surprised me at the time. It is more of a national problem than I realized.
Customers of the Nursery Industry are contributing plant losses to this issue. For every inch of extra soil above the root flare, there will be 1 inch less of actual roots in the ball, depth wise. Fewer feeder roots.
Draw a side view of a root ball. Spades can only go so deep. Draw an
extra inch on the top of the ball and the spade is reduced by 1 inch in how deep it can go.
The newest edition (May, 2004) of the American Standard for Nursery Stock addresses the issue head on. Page 17, under Root Ball Depths, says, “Depth of the ball is measured from the top of the ball, which in all cases shall begin at the root flare.” A drawing helps make it clear.
“Soil above the root flare, from being deeply planted in the nursery as a young plant, as a result of maintenance practices in the nursery, or added during harvest, shall not be included in ball depth measurement, and should be removed.”
The relationship between root ball diameter and caliper has been the primary issue in the past, when a potential customer has asked if a nursery honors or complies with the nursery standards.
This depth issue is new, but important to honor. It is on many minds. It would be wise to begin making a conscious effort this harvest season on this aspect.
It might be possible to make this issue a positive marketing tool, to emphasize that your plants are produced with the root flare visible. That it is not necessary for you to remove any soil prior to digging.
This issue will not go away. In fact, the discussion and fact finding is just beginning. Two representatives of the Morton Arboretum toured several nurseries in Warren County in June.
Only a glance is required to determine if the root flare is visible on most trees and older shrubs. Stems do not normally enter the soil like a fence post. Scratch close to and around the stem to find where the first root is attached to the stem. It should be in the top inch of soil.
Researchers could easily check plants at retail and landscape job sites, asking the source and publishing their findings.