bur oak leaves
I have a bur oak and for the last two year the leaves on the south side have been a lighter green color instead of the dark green on the rest of the tree. Last year there was a lot of aphids and I thought it was related to them (I treated with neem oil and this resolved the aphids). This year I pretreated for aphids and did not have an aphid issue. I still have the same leaf color change but not as significant. The tree is in a yard and I have tried treating the soil with ironite and with a fertilizer with higher iron content since last fall. Any ideas on what the problem is or if this is even something I need to be concerned with? Thanks for your help!
Jefferson County Colorado trees and shrubs
Your oak leaves are chlorotic and yes, you need to try to correct the problem now. Iron chlorosis is is most common reason for yellowing leaves and needs to be corrected with a chelated iron product. The best iron chelate for our area is: EDDHA. You may also consider having your tree injected with iron. Here is some information on chlorosis: http://www.ext.colostate.edu/mg/gardennotes/223.html