Neil Sperry's Mailbag

DEAR NEIL: I've been asleep at the pruning shears. Now I notice I have ivy embedded in the trunks of several of my trees and growing almost to their tops. What should I do?

Don't spend much time worrying. Ivy only damages trees when it (a) canopies over their tops and shades them, or (b) weights them down during ice storms by adding surface area that can hold the ice. Confine it to the trunks by pruning it off horizontal branches and you'll be fine.

DEAR NEIL: What do you do if your soil is gravely? How can you maintain good nutrition?

Feed your plants less per time, but step up the frequency. Instead of fertilizing the turf and landscape every 8 to 10 weeks during the growing season, do so every 5 or 6 weeks, but at half the recommended rate.

DEAR NEIL: How can we eliminate several very large, dense clumps of pampasgrass? Is there a simple way?

Probably the quickest way would be with some type tractor and scoop, but, if that's not available, or if access is the issue, let the clumps grow for a month or two, then spray with a glyphosate herbicide such as Round Up. Once the clumps have died, cut off all the foliage and take a powerful rear-tine rototiller into the mass of dead and decaying roots. It won't be easy, but then you'll be able to scoop out all the fluffy organic matter that's left behind.

DEAR NEIL: Can we prune a jujube tree that has grown so tall we can't reach the fruit? Also, why does the fruit only last for a few weeks before it's no longer of quality?

Jujubes are strongly growing trees with a decidedly vertical habit. Pruning probably won't gain you much relief. As for their lasting qualities, what you have experienced is true for almost all fruit trees. Rarely will they produce longer than two to three weeks.

DEAR NEIL: What kind of grass is best for Texas lawns, and do I need to rototill an old, neglected lawn and start over?

Common bermudagrass is the most durable, lowest-maintenance grass that we have. Undoubtedly your existing turf has bermuda already in it. If the grade is smooth, don't rototill. Mow short (1-1/2 inches), and apply a quality, all-nitrogen fertilizer. Various weedkillers will eliminate all existing weeds (including other types of lawn grasses). Let your nurserymen guide you through those decisions.

DEAR NEIL: I have green moss growing in my St. Augustine in visible patches. It seems to be getting worse. Do you have a remedy?

There is no need to look for a chemical remedy. Moss grows when soil moisture and the humidity are high and temperatures are cool.

It will abate as summer approaches. In the meantime, figure out why that area is conducive to moss, also why the St. Augustine isn't vigorous enough to choke a lot of it out. Work on a means of improving the drainage. If the St. Augustine has weakened and thinned due to excessive shade, you may be able to remove one or two unneeded tree branches and make a big difference. Watch the situation for a few weeks. Ideas will come to you.

DEAR NEIL: I am enclosing two leaves from my gardenia. They are totally blackened. Because the stuff rubs off, I thought I could wash it off with a soapy water spray, but it didn't work. What causes it, and what can I do to remove it?

That's the same sooty mold that grows on other plants' leaves and stems. It is always a secondary invader, meaning that it is invited on each plant by some other issue, almost always from sap dripping on the leaves and twigs.

In your case it's because the gardenia was loaded up with whiteflies last season. They're the small, swarming insects that coat the backs of the leaves with their egg cases. Every time you brush against the plant you'll encounter an armada of the pests. Use a systemic insecticide such as acephate on 10-day intervals to protect the new growth. There is nothing you can do other than hand-washing the leaves to remove the residue from the old leaves. New growth will be clean until another infestation coats the leaves with the honeydew. Aphids and scale insects cause similar problems on other plants.

DEAR NEIL: What is your opinion of bagging or mulching my grass clippings?

I can make a strong case for either. Personally, I collect my clippings and use them in my compost and as a dry mulch in shrub beds. On the other hand, if you mow frequently, and if you use a mulching mower that regrinds each clipping several times so that they're fully pulverized, you can leave them in place to release their nutrients back into the soil. The non-negotiable part of all this is that you must not send them to the landfill.

DEAR NEIL: Over the past several years I have watched my lawn thin out beneath several large live oaks. I have grass growing under other trees in other parts of my yard and it seems to be doing fine. Have you seen this? What might the cause be? All of my lawn is St. Augustine, and it's all treated equally.

This is the most common question I'm asked about lawns: how to handle thin grass beneath trees. No trees that you grow cast any heavier shade than live oaks, and you're seeing the natural progression of the thinning as the shaded area grows larger. No grass is more shade-tolerant, so it's probably time to think about a shade-loving groundcover. I have many, including mondograss (my personal choice for big areas), liriope, English and Persian ivy (problems with last year's really wet soils), Asian jasmine, purple wintercreeper and ferns.

DEAR NEIL: We have lived here for three years, and our bermuda lawn has had dead spots each summer. The lawn people have told me it's from salt leaching up and causing a white substance to appear. What can we do to neutralize the salt?

Begin with a complete soil analysis from the Texas A&M Soil Testing Laboratory. They will not only determine your soil's nutritional levels, but they'll also identify its pH (acidity or alkalinity). Most importantly, you will also see its concentration of soluble salts. Ask that they interpret each result for you. Total charge will be $25-$40 for the test, and it will prove or disprove whether the soils are at fault. Contact your County Extension office for the sample bags, mailing boxes and instructions.

Be sure the drainage in the area is good so that excess mineral salts of all types can leach out of the soil, then water heavily to rid most of them.

You may end up using gypsum to replace the sodium on the soil particles with less harmful calcium. Finally, you may find that there are outside issues entirely that are causing the dieback. They might include bermuda mites, a fungal problem, mowing too high or excessive shade in certain portions.

It's a witch hunt. Good luck on it.





Have a question you'd like Neil to consider? Mail it to him in care of this newspaper or e-mail him at mailbag@sperrygardens.com. Neil regrets that he cannot reply to questions individually.

Neil Sperry
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