Gardening 101: Hackberry leafrollers invade North Texas

NORTH TEXAS (CBSDFW.COM) — I start this story with a startling fact; the hackberry tree – which comes in two varieties – is very common in North Texas. The tree is infamously found along stretches of powerlines, where birds eat the seeds off the tree and “disperse” them later where they rest until the time is right for growing. 

With such an efficient distribution program making use of the birds’ free labor, hackberries are found just about in every picture of trees in North Texas. They make up an amazing 20% of the total canopy; about one in five trees is a hackberry.

When things go bad for hackberries, it is not something that can easily hide from us. There is a specific pest that attacks the trees during the warm season, late spring and on, called the hackberry leafroller.

The hackberry leafroller is a small green worm that looks like a tiny inchworm. It nests in the tree’s branches and eats the leaves. 

When they get fat enough, they spin silk drop lines and drop to the ground. There, they borrow in and wait until the next warm season to emerge as a rather plain looking brown/gray moth.

This year, North Texas suffered a major invasion of leafrollers. The hot and dry weather all summer kept the population at bay, but the sudden eight or nine inches of rain that soaked us within 24 hours back in the third week of August has inspired trees to grow out some new foliage and resulted in a population boom of leafrollers. 

Even worse, many of their natural predators were diminished by the same weather conditions leading up to the big rain, so the entire summer population of leaf rollers arrived all at once with very few enemies around to keep them in check.

There were some areas of the DFW Metroplex absolutely overrun with them. Back in 2015 we suffered a similar invasion, but that one was largely confined to the Grapevine area. This outbreak seemed to span the entire metro. Trees looked like they were dying, their black sand of excrement also covered everything. Yuck.

But here is some good news. Hackberries had all season to build up their winter sugars necessary for dormancy and spring leaf out. 

Infected trees will lose their leaves at the end of the growing season, but they’ll all come back in spring and be just fine. And even though there was a huge population explosion this year, that’s no indication that portends another large population next year. It is always dependent on the weather and what trends hold across the summer months.

The same weather pattern led to an explosion of the aphid population across our area. Their “honeydew” waste from feeding on new leaf growth coated entire trees, cars, sidewalks and outdoor furniture in some places. 

As frightening as this all was to look at, again, it shouldn’t be much a burden on the trees themselves. Since the population explosion happened at the end of the growing season, some rain and cooler temperatures will make all of it go away.

All in all, mostly bark and not much bite. Mostly bark that won’t harm the bark of the tree so to speak.

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