Questions on: Maple
Ron Smith, Horticulturist, NDSU Extension Service
Q: I have five maple shrubs, but only one has the light color veining its leaves. What nutrient is lacking? Is it too late in the season to fertilize? In general I have been using Miracle-Gro. Should I be using something different? (Washburn, N.D.)
A: I doubt that any fertilizer will pull your Amur maple out of its chlorotic funk. Generally, when a tree is stressed, it shows an iron deficiency--which yours is doing. I suspect a root rot problem of some type. Although you will not get any response now, put some chelated iron into the soil around this tree, and hope next spring it can outgrow whatever is ailing it. If the same symptoms appear with the growth next year, get the tree out of there, root and all.
Q: I bought and planted an amur maple shrub this spring because I had seen some
beautiful ones in a nearby park last fall (about 5 feet tall). Today when I was
walking, I went to look at the amurs in the park to see how much they had grown since last year. One had two of its branches dead, and the others' leaves were
being eaten away by something. My little bush is still doing fine, but I am wondering if they need some sort of special care and what sort of bug attacks them. Regina,
Saskatchewan, Canada, e-mail)
A: Usually the amur maples are pretty indestructible, although they can be hit by cottony maple scale, fall webworm and maple bladdergall mite, as well
as a host of other insects, such as sawfly larvae and any number of leaf-munching beetles.
Amur maples have been known to be injured by severe winter temperatures, which could place them under stress and make them attractive to
destructive insects. Generally this is what happens to seedling selections that are planted out, not cultivars that have been selected for superior
performance in many areas.
Encourage good growth of your amur maple throughout the summer with watering and fertilization. Do not fertilize after Aug. 1 to allow plenty of time
to harden up going into the winter. Place a protective barrier around the trunk for the winter to keep the cottontails from debarking the tree (keep in
mind where the typical snowline is in your area). Practice selective pruning after leaf-out in the spring and remove any dead or cankered wood to limit
harboring places for pathogens or insects. Finally, keep the grass, especially turfgrass, away from the base of the tree, and it will establish faster and
grow much better.
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