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Neil Sperry: Sooty mold ugly but harmless for plants

Neil Sperry: Sooty mold ugly but harmless for plants

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Sooty mold on lemon

Sooty mold covers this lemon and its leaves. The fungus is unsightly, but it doesn’t affect the plant.

DEAR NEIL: Last year our 7-year-old Meyer lemon tree produced an abundance of beautiful lemons and foliage that was bright green. This summer it developed whiteflies.

I applied Neem oil for three weeks and got rid of the whiteflies, but then black, dirty spots started to develop on the leaves. Before long, the spots spread to the fruit. How do I treat this?

Dear Reader: What you are seeing is a fungus called sooty mold. You will also see it on crape myrtle leaves after crape myrtle aphids and scale insects attack them. You will also see the mold on Texas sage, cotoneasters, loropetalums and other shrubs that attract aphids or lace bugs.

It will even develop on other plants and hard surfaces beneath the infested plants. It stains our concrete paver driveway beneath our pecan trees when aphids infest the pecan leaves late each summer.

Sooty mold is basically harmless to the plants. It is just unsightly. You can wash it off the fruit very easily. The bigger issue is in eliminating the substrate in which it grows.

It gets its start in a sticky substance we call honeydew. That is the excretion of sap that passes through the bodies of those sucking insects.

The sum of it all: to get rid of the mold you really must get rid of the insects. Citrus is indeed bothered by whiteflies, but there are also citrus scale insects that can give off honeydew, so check your plants closely and choose the appropriate insecticide.

DEAR NEIL: I saw your notes that digging and transplanting an established tree should wait until the middle of the winter when the tree is completely dormant, but I saw the instructions after we had just dug this 10-foot live oak that had come up in a bed of many other plants where it was very crowded.

It is now in its new home where it will have ample room. What care should we give it now,? Extra water? Root stimulator? It has two trunks, but they are not attached to one another.

Dear Reader: I agree that it is two separate seedlings. To compensate for the roots that were lost in the digging, I would suggest trimming each tree back by half or thinning their tops by that amount.

That’s going to involve removing most of the small branches on the taller tree, but it will soon produce more. You just have to do it to help the trees recover. You can send them out later.

Yes, apply root stimulator monthly from now through next year, and do not allow the soil to become dry to the touch. Watering frequency, however, will depend on temperatures and rainfall.

DEAR NEIL: I don’t know what kind of tree I have. Actually, there are two of them, one of which has developed many of these growths.

This tree is huge and takes up a large part of our yard. What are these growths, and do I need to be concerned?

Dear Reader: These are called “burls.” They are abnormal developments of bark and wood tissues of the trunks of trees.

Some species of trees are highly prone to forming burls, while they’re quite rare with others. Woodworkers will tell you that burl grain is actually quite lovely and highly prized, but landscapers aren’t quite as happy to see them forming.

I can’t tell what type of tree this is, but it appears that it might be a fruitless mulberry. That really doesn’t matter, however, because there isn’t anything you can do to prevent or control burls anyway. You can’t prune to remove them. You just have to look at them.

If the tree becomes unsightly to the degree that you want to have it taken out, you would probably want to replace it with a more durable species. Let a certified arborist advise you.

DEAR NEIL: Do I need to remove the seed pods from my Texas mountain laurel in order to encourage more blooms next spring? They seem to persist beyond just one year.

Dear Reader: No. The plants will bloom each year regardless of whether there are seed pods still hanging on them or not. It’s not uncommon for the pods to remain in place into the second year.

DEAR NEIL: I really need your help quickly. We had a beautiful St. Augustine lawn for many years, but now large patches are developing suddenly.

We can’t afford to buy more grass. What can we do?

Dear Reader: I note that your photograph was taken just a few days ago, already well into November.

This is a fungus called brown patch. Texas A&M turf specialists are now actually calling it “large patch.” It sounds like that matches up with the description that you gave it.

The good news for you is that it will not kill the grass. It does weaken it, but the grass will recover. It attacks only the leaf blades and only where they attach to the runners.

The fungicide Azoxystrobin is your best means of controlling it, but normally you would want to apply it before the patches become as evident as they are now. That could stop it from disfiguring the lawn at all.

This grass in your photo will green back up again if it has time before the first frost in your part of Texas. Otherwise, it should be fine come spring.

Have a question you’d like Neil to consider? Email him at mailbag@sperrygardens.com. Neil regrets that he cannot reply to questions individually.

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