Homegrown: Emerald queen maples, broadleaf removal

I have three emerald queen maples planted in a lawn now for three years. One of them showed signs of iron problems last year. Should I be adding iron, and what way would be best to apply it?

— Kim

The first thing to know is the type of iron to use. Always use a chelated form of iron.

Elemental or metallic iron such as iron sulfate is of little use in our alkaline soils since it ties up quickly and becomes unavailable to the plant.

A chelating agent is simply a molecule attached to the iron that keeps it available to the plant for an extended period of time. There are different chelating agents out there, and some will last longer than others but eventually they all break down necessitating reapplication of the iron.

I like to start applying the iron when the first little leaves are visible on the tree, usually late April.

Since your trees aren’t that big, apply it in a circle with a radius roughly equal to the height of the tree. Large older trees are best done this way as well, but you can get away by applying it to a donut shaped area centered on a circle with a radius equal to the height of the tree (which is often the spread of the branches or the drip line).

I’ll calculate the rough square footage of the area I want to cover and use the directions on the iron package that tell me how much to apply for a specific area.

Since the chelating agent will break down, you may have to reapply it about six weeks later and in severe deficiencies, even apply a third application.

The last thing to remember is that whenever you apply the iron, apply a nitrogen fertilizer as well. Use a cheap lawn food or ammonium sulfate to do it. Both the iron and nitrogen can be simply spread over the surface of the area and watered in well.

Is there a particular way to apply broadleaf weed remover to the lawn to make it more effective? The last couple of years I have had no luck with anything I used.

— Brad

The first thing I want to know when I start talking about weed control is what weeds we’re dealing with.

There are a whole bunch of different weeds — seems sometimes like we have all of them here in western Colorado — and each of them can require a specific control strategy.

The problems you’re having may be with the specific herbicide you’ve been using or the timing or method of application. If you have any samples you could bring in, we could identify them and recommend the best way to go after them.

When we talk about broadleaf weed control, remember that there are a bunch of different broadleaf weed killers available and several ways to apply them.

A lot of folks have used 2,4-D over the years, which was one of the first of this type of herbicide. It’s a safe product to use since it doesn’t have much soil activity. I don’t think it does all that good of a job with some of the tougher broadleaf weeds.

The product I like best for general broadleaf weed control is a Fertilome product called Weed Free Zone. It contains 2,4-D plus three other related herbicides. It does a great job on most all the broadleaf weeds we encounter.

The way I’ll go after perennial broadleaf weeds in the lawn is to wait until they sprout up then spot spray with the Weed Free Zone. I’m not a big fan of general area sprays since sometimes the spray goes places I didn’t intend for it, plus I tend to spray more of the herbicide that has the potential to harm trees and shrubs in the vicinity.

One or two spot sprays usually does the trick without risking you desirable ornamental trees and shrubs in the yard.

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Dennis Hill is the nursery manager at Bookcliff Gardens, http://www.bookcliffgardens.com. Send questions to Bookcliff Gardens, 755 26 Road, Grand Junction 81506; or e-mail .(JavaScript must be enabled to view this email address).


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