I have iron chlorosis affecting my autumn blaze and red maples. I read iron sequestrine 138, or Miller's ferriplus are indicated for this problem. I cannot find this in area garden stores so I need to order online. How is this best applied to trees and when?
Thanks for your help!
The first thing you need to do, if you haven't yet, is get a soil test to find out the pH of your soil and if it contains "free lime". Once you know this you can determine what type of iron chelate (if any) will work for you. Visit http://www.soiltestinglab.colostate.edu/ for more info on soil testing. You will want to click on the link "Horticultural Applications for Gardeners".
In some parts of Colorado, the soil pH is high - above 7.4 or so. Maples and other plants suffer in these type of conditions. There is iron in the soil, but high pH doesn't allow the tree to take it up. Applying iron products to the soil, can help in certain situations but it is only a temporary fix. You will have to do this routinely to provide the iron for your tree. If you have free lime as determined by the soil test, there is nothing you can do as the lime in the soil prevents the iron chelates and additives from being effective. Here is a fact sheet that will give you additional info on this problem and ways to minimize it - including making sure to not over water in the spring time and minimize soil compaction. http://www.cmg.colostate.edu/gardennotes/223.html
The first step is to get a soil test and figure out what you are dealing with.