Hollow holes

Yellow-bellied sapsuckers can sometimes damage landscape trees by creating a row, or multiple rows, of holes in bark. In general, sapsuckers rarely cause long-term damage to trees because the holes are shallow.

WILLIAM M. JOHNSON/Courtesy

Q: The trunk of my pecan tree has several horizontal layers of numerous holes with each layer spaced an inch or two apart with the holes in each layer being rather evenly spaced from each other. What caused the holes?

A: Several phone calls to my office this month were questions on the cause of a horizontal series of holes appearing on the trunk or branches of pecan trees.

The holes are spaced rather uniformly in distinctive rows around the trunk or even major branches, with each hole being about the diameter of a pencil and only about a quarter inch or so deep.

These holes are made by a woodpecker, called the yellow-bellied sapsucker. At least two reasons are provided in literature for why this woodpecker does this. One reason given is that these birds peck out holes to consume the sap and indeed they may show a preference for one tree in the yard and will ignore another tree right next to it that is the same species. In fact, these birds will return again and again to a tree.

The other reason given is that the yellow-bellied sapsucker pecks out the holes for the apparent purpose of providing a place for insects to hide. The bird supposedly returns periodically to eat the insects that seek refuge therein. In general, sapsuckers rarely cause serious damage to trees because the holes are shallow.

Pecans are not the only trees affected, as oaks and other landscape trees are also frequent targets of the birds’ insect-mining efforts. Incidentally, if the holes had been random in occurrence, then the likely culprits would have been insect pests known as tree borers.

Q: How often do day lilies need dividing? What is the best technique to use?

A: Day lilies should be divided every three to five years, depending on how crowded the plants are and if flower production is declining. Division is best done in early spring, as new shoots begin to emerge, or in the fall after the plants are dormant.

While most day lily varieties are quite tough, I think it is beneficial to wait until cooler fall temperatures prevail to dig them. When dividing overcrowded plants it is best to dig up the whole clump.

Separate clumps by using two spading forks inserted back to back into the middle of the clump and then prying a clump apart. This is less damaging to the roots than cutting, which injures many feeder roots. Cut the foliage back to about 4 inches from the ground.

If you are going to replant in the same location, replenish the soil before planting with well-rotted compost and a fertilizer high in phosphorus for root development. Larger size day lily varieties may be planted up to 30 inches apart and smaller size varieties as close as 12 inches.

Q: The upper sides of the leaves on my crape myrtle have a black moldy growth. They also produced fewer blooms this summer compared to last summer. What could be wrong with them?

A: The presence of black mold on the leaves of crape myrtle indicates that an insect known as the crape myrtle aphid is likely to be present. This insect will feed on the leaves of crape myrtles beginning in late spring and continuing through August. Ladybird beetles will eventually bring them under control but it is often too late to prevent the occurrence of black moldy growth.

Crape myrtle aphids excrete honeydew which accumulates on leaves’ surfaces below aphid populations. Honeydew is commonly seen as a shiny coating on the tops of leaves and stems. Molds and other microorganisms can grow on these surfaces utilizing the rich sugary honeydew as a food source. Black sooty mold can turn the entire plant an unsightly black color detracting from the visual aesthetics of crape myrtles.

If applied with proper dosage and proper timing (during late spring when aphid populations start to increase), systemic insecticides (such as imidacloprid) can be effective in controlling aphids. Insecticidal soaps and horticultural oils (such as neem oil) are an environmentally friendly option. The key with using the soap sprays and horticultural oils is that the oil must cover the aphids when you spray so thorough coverage is essential.

Q: What causes okra pods to be crooked and bent rather than straight?

A: This condition is most likely caused by insects feeding on the pods. Certain sucking insects, such as stink bugs and leaf-footed bugs, inject chemicals into the pods causing the pods to stop or slow down growth on that side of a pod. The other side grows normally if not fed upon, resulting in a curved or bent pod. The pods can still be eaten.

William M. Johnson is a horticulturist with the Galveston County Office of Texas A&M AgriLife Extension Service. Visit his website at http://aggie-horticulture.tamu.edu/galveston/index.html.

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