I have both a pin oak & river birch with this problem, Chlorosis (Iron deficiency)
1) The illinois soil has a good supply of iron (FeSO4) but the soil pH is 6.8 For the iron to be utilized by these trees the pH needs to be 5.5
2) I wanted to use sulfur to lower the pH but the directions say to "mix the sulfur in the top 6 inches of soil".
3) these trees are in an established lawn and the trees have a caliper of 20 inches or more
4) HOW can I incorpoirate the sulfur under these conditions?
5) There was a sugestion that if the soil pH was lowered more than 1 point it would result in tieing up nitrogen & iron ect.... is this so?
6) tried to contact the supplier of the sulfer (Fertilome) several days ago but no response.