Powdery mildew won’t ruin crape myrtles

By Neil Sperry | Published Wednesday, February 19, 2014

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Dear Neil: Every year my crape myrtles get white mold. I’ve tried a three-in-one rose food on them, but it doesn’t seem to help. Am I just not using enough, or should I be doing something else?

That’s powdery mildew, and the good news is that it’s not terribly harmful. It may cause a few leaves to fall off, and it may even ruin the first round of blooms once in a while, but the plants will be fine in the long run.

I would recommend applying a labeled fungicide from your local independent garden center. They tend to handle more specialized products for less common problems like this. It’s probably not best for you to be applying more and more fertilizer as you try to stop the spread of a disease.

Dear Neil: I’m attaching photos of two different winter weeds I have in my St. Augustine lawn. What will be my best control for them? I also have crabgrass in the lawn in the summer. Is there a control for it that won’t hurt my St. Augustine?

The smaller of your weeds is henbit. Anytime now, you’ll see it burst forward with little purple flowers, if it hasn’t done so already. Mowing at the regular height will eliminate almost all of it.

The other spreading weed is chickweed. Both of these can be controlled with a broadleafed weedkiller spray applied on a warm, late-winter day.

The better way: they can be prevented by an application of Gallery pre-emergent herbicide in the first 10 days of September. As for crabgrass, the best products for use in urban landscapes are Halts and Dimension. Apply them two weeks prior to the average date of the last killing freeze in your area. Repeat the treatment 90 days later for a full season of control. There is no post-emergent control that is safe for St. Augustine.

Dear Neil: I am growing an avocado in a container, but I’d like to put it out into the ground. Does it need to be grafted to produce fruit? Which side of the house would be best for it in terms of winter protection?

Oh, my. Avocados can handle no freezing weather, so you are destined to grow it in a container unless and until you move to the southernmost part of Texas. Even there, they can freeze. The types that produce fruit commercially are, indeed, grafted, but there is no point in doing that with yours. Avocado trees grow to be quite large. It would be like trying to get a pear tree to produce fruit inside your house. Enjoy it as a novelty. When it gets too big to handle, discard it and start another.

Dear Neil: If I wanted to divide monkey grass to line my sidewalk, what size of clumps should I dig, and when is the best time to do it?

Mondograss (aka monkey grass, lily turf and ophiopogon – all the same plant) can be dug and moved at almost any time of the year. Late winter and early spring are very good times, as the plants will quickly reestablish in their new homes. Tennis-ball-sized clumps that you plant on 8-inch centers will give you a quick fill. Plant them closer together if you’re planting on a slope.

For the record, you’ll want some type of barrier such as metal edging driven almost all the way into the ground to keep your mondograss from spreading into your lawn. Be sure, too, that you do actually want to line your bed with any plant. That will draw a lot of attention to the walk, when it’s usually better to draw attention more toward the front door itself.

Dear Neil: Is there any way to kill a tree that just keeps sending up sprouts all over my yard? I’ve tried Round Up, and it didn’t work. What will?

My answer will assume that you want to get rid of the mother tree as well as the sprouts. They are tethered to that larger tree, so anything you put on them will immediately be taken to it. Use a broadleafed weedkiller (containing 2,4-D) as a spray as the sprouts are growing this spring and early summer. Round Up (original glyphosate formulation) is a grass killer and isn’t nearly as effective on non-grassy species. Hire an arborist to remove the stump and roots of the original tree.

Have a question you’d like Neil to consider? Mail it to him in care of the Wise County Messenger, P.O. Box 149, Decatur, TX 76234 or email him at Neil regrets that he cannot reply to questions individually.

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