Want to produce pecans in Texas? Be sure to address these common issues
If you’re going to produce pecans here in Texas there are several issues you’ll need to address. I’ve made a list of the most common. Let’s check them off one at a time.
▪ Large fibrous webs being built on limbs. On closer examination you notice that there are larvae within the webs. Leaves are being devoured voraciously as the webs become larger rapidly.
Webworms begin building their webs at the ends of the branches. At the outset the small number of caterpillars will cover a few leaves in a cluster the size of a football. That is the time to react. Use a long-handled pole pruner to clip off that growing tip of the branch and let the web drop to the ground. Gather all the clipped webs up and put them into trash bags, then send them off to the landfill. Mission accomplished.
If you wait a week or two, however, the webworms will have built webs as big as a pig. You won’t want to trim off limbs of that size, so all you can do is pull the webs open with the pole pruner. Expose the larvae to the elements (including hungry birds) and your problems should be solved.
Option 3 is to leave them alone entirely and let nature take her course. That’s what we all have to do when the webs are so high that we can’t reach them from the ground. They won’t kill the tree. Eventually, they’ll come tumbling down as the leaves fall in November. But most of us choose to clip them out if we can. And, just to have said it, spraying is not much of an option. It’s difficult to reach the webs with the spray and to get the spray into the webs.
▪ Leaves falling prematurely — brown and crisp. This is usually just a pecan’s reaction to hot, dry weather. Look up and down your street, and odds are that you’ll see many other tree species dropping their leaves as well. It’s hard for them to meet the demands now that temperatures have reached into the 90s on a daily basis. Soaking the soil deeply every couple of weeks will help, but it won’t stop the issue.
▪ Leaves marked with yellowed segments between veins. This is the work of the black pecan aphid. I’ve been seeing a great deal of it on my Metroplex pecans the past several weeks. It will cause many of those leaves to drop prematurely, so it does do some amount of damage to the plants. However, like many of the other problems, it would be difficult for a consumer to correct this problem through spraying. It’s probably best just to keep an eye on things and hope for a better year next year.
▪ Leaves taking on sticky, shiny coating. Small drips of “honeydew” coating other leaves, stems, and surfaces below. Your plants have been visited by the yellow pecan aphid. This honeydew is their calling card, and it’s really annoying. Worse yet, sooty mold, a nasty black fungus, will grow in it. Hopefully the aphids won’t be as bad as they were several years ago. That was when you could hear your shoes sticking to the sidewalk or driveway. In the meantime, keep the honeydew pressure-washing off hard surfaces below.
▪ Pecans falling prematurely — still in shucks and green, perhaps with black blotches. Pecan scab fungus is probably responsible. You’ll know for sure if the shucks turn black almost immediately. This disease infects the pecans in late spring and early summer. There is no spraying that will be effective this late. In the future, plant a scab-resistant variety and start your spray problem by the end of May if you hope to produce pecans. Oklahoma State and Texas A&M have details of products and timing.
▪ Small twigs and branches falling to ground, appearing to have been cut with a sharp knife. Twig girdlers do this. They’re large beetles with very sharp mouthparts. The females score the twigs, then they lay their eggs on the portion that will eventually fall to the ground. The larvae develop in the decaying wood, then fly next spring, mate and start the process over again. It’s all fascinating once you understand how it’s all happening. There isn’t much you can do about it other than gather up the twigs and tell the kids and grandkids about nature’s miracles.
▪ Rows of holes around trunk or major limbs. Woodpeckers and sapsuckers have spent some time loving your tree. It looks like someone has fired rounds from a machine gun across the limbs. The holes will all be at one level, fairly neatly spaced. Borers, by comparison, will be completely randomly arranged. The birds seldom do damage to pecans and it’s against the law to harm them. I just let my trees heal naturally. No net problem.
▪ Lower or internal branches dead or declining. If your pecan trees are growing among other trees, pecans included, and if their branches intertwine, it’s only a matter of time until you’ll start seeing lower limbs start to decline and die. State pecan authority George Ray McEachern of Texas A&M once said in a meeting I attended, “When two pecan branches touch, one of them will die.”
I live in a pecan forest and I’ve never forgotten that message. I’ve seen it repeated scores of times. The first year the less dominant branch stops putting out new leaves. The second year the leaves at the end of the branch thin and drop. The third year the branch is dried and dead. Somewhere along that line I alert my certified arborist that it’s probably time to remove that weaker limb before it comes crashing down.
