Get those fall leaves off your lawn ASAP

By Neil Sperry | Published Wednesday, January 15, 2014

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Dear Neil: I purchased a house with four mature crape myrtles along the fence in my backyard. They are about 15 feet tall, and their trunks are about 18 inches from the fence. My neighbor has a pool, and the petals are constantly falling into it. Can crape myrtles that tall be moved from clay soil to sandy loam? When is the best time, and how large should the root ball be?

If the crape myrtles are otherwise healthy and well-shaped, you bet they can be moved. They’re among our most forgiving landscaping plants. I moved a 20-foot-tall crape myrtle that had been in the same spot for 30 years just last February. It survived the move and bloomed all summer.

The size of the soil ball is related to the diameters of their trunks, not to the plants’ height. Hopefully you can remove a panel of the fence long enough to do the digging. As a rough guess without seeing the plants, I would figure that the soil balls should be 30 to 34 inches in diameter and 24 to 30 inches deep. That may be more than you want to tackle yourself, but a landscape contracting crew could make quick work of it.

Winter is the time for such a move, and you’ll want to thin out the plants’ top growth to compensate for the loss of roots that they’ll encounter. Do not, of course, top them. The clay soil will be great for forming soil balls. Stake the trees securely after the move, until they can anchor themselves into the sandy loam. That will probably take a year or two.

Dear Neil: We have several large pecan and oak trees and mostly St. Augustine. Is it helpful to the grass to leave the leaves on the ground in fall and winter, then mulch them in the spring? I don’t worry so much about how neat my yard looks. I’m more concerned with what is best for the grass.

Good for you for worrying about the grass. However, you really need to get them off the lawn as quickly as you can.

It’s true that they can keep the grass a little greener if it turns really cold, but leaves trap moisture and warmth, and those two factors can combine with St. Augustine to lead to serious disease problems. I’m surprised you haven’t encountered brown patch in previous falls.

I have the very same situation in my own lawn (pecans, oaks and St. Augustine), and I try not to leave the fallen leaves on the grass more than a few days. Run the leaves through your mower, and use them as mulch beneath shrubs and in perennial gardens. Or you can put them directly into the compost pile.

Dear Neil: My three-year-old mondograss leaves are turning brown. It started at the tips of the leaves, and now half of the plants are brown. What is causing this?

You really hit me on this one. As the pecans and oaks I just referred to have grown larger and larger, I have converted to more and more mondograss in my own landscape. I dig and divide my own, and I’d guess we have probably 7,500 square feet of it in our rural landscape.

In answer to your question, the plants probably got too dry at some point late in the summer or early fall. I have seen that happen when sprinkler heads in my own landscape haven’t functioned properly. I have never seen an insect or disease bother regular mondograss. I have seen leaf diseases attack dwarf mondo and the plants’ cousin, liriope, in overly wet soils, but I’ve never seen that problem show up on regular mondo.

If you think a disease might be involved, dig several tennis ball-sized clumps showing the damage. Pack them carefully (without adding water), and ship them one- or two-day delivery to the Plant Disease Diagnostic Laboratory at Texas A&M. Include an explanation of what you’ve been seeing. They will culture the samples and tell you if they find any pathogens. You can find mailing information and payment instructions by searching for the lab online.

Dear Neil: I have a cottonwood tree that seems to be declining. It’s quite large, and it shades our entire backyard, but it didn’t have as many leaves this past year as usual. How long do they live, and how can I tell if it’s having some kind of problem?

Average life expectancies with fast-growing trees like cottonwoods are hard to estimate because many of them die young, in the case of cottonwoods and willows, from cottonwood borers. However, cottonwoods that survive those first 15 or 20 years can often keep on growing for another 30 years. However, when a large cottonwood begins to thin out, and especially if it has dead branches in its canopy, it’s time to call in a certified arborist – sooner rather than later. It may have a large hollow area within its trunk, and it may be ready to split or fall. I don’t mean to alarm you, but this sort of decline keeps progressing, even in winter, so you really need to get help soon.

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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