Treatment for Yellowing Leaves On Oak And River Birch AKA…Iron Chlorosis
Trees can’t talk, but they do communicate if only we pay attention.
Oak trees (especially Pin Oak) and River Birch are supposed to have medium green to dark green leaves but quite often they start exhibiting lime green or yellow leaves. This condition is known as Iron Chlorosis and it means your tree is telling you it is unhappy with its soil conditions. Left untreated, these trees will be in a downward spiral declining more and more every year until it dies. Depending on the trees condition, death can occur within 3 to 5 years.
Iron Chlorosis is caused by soil that is too high in Alkaline, a common occurrence in our area. When the alkalinity in the soil reaches 7.5 or higher the Iron that is in the soil naturally becomes insoluble for tree roots to absorb. Since Iron is the main mineral that Oaks and River Birch rely on, these conditions present a life threatening condition.
Once tree leaves start turning yellow it is because they lack the all-important green chlorophyll which is crucial for the trees survival. Chlorophyll is needed to absorb the sun’s rays which then turns it into the starches and sugars necessary for trees to gain energy and live long healthy lives.
Tree Green systemically injects chelated Iron directly into the trees sap system through the trunk. Within 3 to 4 weeks this process will ‘green up’ the trees leaves dramatically, allowing them to once again absorb sun energy. We usually perform this process once every 3 years.
The photos above show an Iron deficient Oak on the left and the same tree, recovering, two months after our injection.
Note…This treatment process will not keep the tree alive indefinitely but once treatment is initialized we can extend the life of the tree from 10 to 25 years if the treatment plan is followed. The length of time the tree lives once treatment begins varies depending on the soil conditions and the type of tree that is being treated.
We do not apply Iron as a soil treatment to be absorbed by the trees roots due to the fact that any ‘green up’ that occurs will be minimal and short lived because the high alkalinity in the soil that caused the Iron Chlorosis problem in the first place prevents additional Iron from becoming soluble enough for the tree roots to properly absorb it. This is why we bypass the roots entirely as the main method of treatment and go directly through the trunk.
We also do not recommend acidifying the soil to reduce its alkalinity. Although this process is an option, it is not one that most homeowners are willing to adopt once they consider the following. Tree roots are far reaching and as such share root zones with other trees and shrubs. Adding an acid based product in high enough quantities to help a tree with an Iron deficiency will create issues for other trees, shrubs and even the lawn within its root zone.