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Complete Forecast for  Jul 24 2008

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. Avocadoes 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: What causes a thick, white substance to form on the surface of plant leaves? It ends up looking like the icing on a donut.

That's honeydew that has congealed and crystallized. It's produced by several types of insects including scales, whiteflies and aphids. It's really not a huge cause for concern, but it's disfiguring. In many cases, black sooty mold will also grow within it, making the plant even less attractive. Wait for new leaves this spring. Prevent future episodes by treating for the insects as needed.

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. Round Up 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.

DEAR NEIL: I planted a new bed of shrubs in October and I'm wondering when I should feed them. They include fringe flower, nandinas and Indian hawthorns.

Apply a high-nitrogen granular fertilizer in March and monthly the balance of the growing season. Water it deeply into the soil each time that you use it. These shrubs were planted out of pots, so all of their roots are intact. They are capable of taking up nutrients right away.

DEAR NEIL: How do I eliminate stinging nettles in a lawn?

Apply the same broadleafed weedkiller mentioned earlier. That one category of products will eliminate all types of non-grassy weeds. Treat while the nettles are growing most actively.

DEAR NEIL: I have a beautiful red oak that is about 3 years old. Early last summer the bark began to peel away on one side. This winter the peeling section has gotten bigger and is going around the tree about 2 feet up the trunk. Will I lose the tree? Photos are attached.

What you show in the photos looks like the characteristic sunscald to which I referred in an earlier question. Your tree may also be infested with borers due to the ongoing injuries from the peeling bark. Spray monthly with a borer preventive, and wrap the trunk to protect against any further sunscald. You may need to thin out the top growth to compensate for the loss of conducting tissues. You may, indeed, lose this tree. Be sure you always wrap the trunks of new oak trees, also Chinese pistachios.

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.