birch tree diseased leaves
I am really worried about our Birch tree, the tree in general looks weak and thinned out. Many of the leaves are curled up with a white coating on the underneath. We were told that it needed more iron and had them treat it with injections but it's obvious there is something else going wrong. I really want to save this tree if possible. What can you tell me
Denver County Colorado
The leaves are yellowish with greener veins which is a classic symptom of iron chlorosis in trees planted in our clay soil. Chelated iron is often applied as a treatment.
The canopy looks thin, possibly a result of ongoing chlorosis but maybe a dieback issue related to insufficient watering. In your first photo it looks like the tree may be in a bed with some junipers raising the question of how the tree is watered and how much supplemental water it receives. While cold-tolerant, birches are not "xeric"; they have high water needs. If your tree is watered with drip irrigation and the emitters haven't been adjusted for root growth since it was first planted, you may need to add emitters and locate some of them further out from the trunk. Birches also require winter watering during dry winters. If you haven't been winter watering, you should start. http://planttalk.colostate.edu/topics/trees-shrubs-vines/1706-fall-winter-watering/
The white on the leaves appear to be aphids, a common insect pest that is abundant this year. Their numbers run high in the spring but then taper off later in the summer. You can hit them with a blast from the hose to wash them off. If that's not sufficient, there are chemical insecticides labeled for controlling aphids; however, those products kill the good with the bad and should be used only as a last resort, if at all. Here's some more information: http://planttalk.colostate.edu/topics/insects-diseases/1402-aphids/
Thanks so much for the advice! I will be on top of this. Maybe the tree is not a goner! Hope so..