to find a solution for use in Toronto. Suggested treatment is for application of iron chelate but Sheridan Nurseries does not carry any and doesnèt know of any sources. Need a source of iron chelate or another product that could help this problem Thank you.
Hello, and thank you for writing.
For a bit of background, the variety Freeman maple has many cultivars of Acer x freemanii, but initially was created as a hybrid of a red, and a silver, maple. While it is generally considered to be less likely to suffer chlorosis, nonetheless, your tree is unfortunately experiencing this. Treatments can vary from stem, to leaf to soil. If someone suggested you apply iron chelate, then perhaps they determined the soil is above pH 7, which is the neutral point between a higher alkaline, and a higher acidic rating.
Many arborists elect to maintain soil pH at 6.5, or lower, through use of soil amendments, taking care not to overwater the tree, and vigilantly maintaining good drainage. One strategy to lower soil pH, is to incorporate acidic amendments, such as peat moss, or very well composted leaves. Alternatively, treatment might be the addition of chelated iron to the soil, as was recommended to you.
For further reading, please see this detailed reply by Toronto Master Gardeners to another similar query re soil testing.
While Toronto Master Gardeners does not make specific suggestions regarding retail options, we see there are several hardware stores, and nurseries, who sell iron chelate in powder, or liquid, form and package instructions should be followed exactly, for best results.