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Trunk troubles of springtime becoming more evident this year

You can always expect tree trunks to show up for the big spring dance with a variety of issues.

This year it’s more evident than ever.

Because it’s easy to overlook problems when they’re hiding in plain sight, I thought I might send out some alerts. Check your trees for any of these.

Bradford pears doing the splits

This happens every spring. Unfortunately, this tree has very narrow branch angles, and moisture and debris get caught between those trunks to a point that the joints are no longer solid. All it takes is a gust of spring wind or a bit of a downpour on new foliage and the tree may split half in two.

Sadly, this happens to almost every ornamental pear. With Bradford pears it’s usually by the time they reach 15 or 20 years old. You may notice that interior trunks are showing yellowed leaves while the outer branches remain green and normal. That’s because nutrients don’t flow normally through the compromised tissues. It’s difficult even to prune to avoid this. The tendency to produce the very narrow V-shaped crotches is just so strong that it’s going to happen no matter what.

Some people try to salvage whatever is left of their trees after part of it splits away. That’s not a good plan, though, because the internal wood has already been damaged. It’s only a matter of time until the rest comes tumbling down. It’s best to have the tree removed and the stump and major roots ground out so that you can replant with some other species.

Bark splitting due to extreme cold

Some of our major shade trees are showing cracks in their bark that look like dried leather. You might compare this to a windshield crackling when it heats up too quickly in winter. Bark is a dead tissue, so as a tree’s trunk expands in size, it’s normal for the bark to slough off. However, that’s usually in sheets, not in these oddly shaped little chunks.

Arborists and foresters tell me that the hope is that trees will quickly form new bark where these pieces have come loose. Just inside the bark is a cylindrical tissue called the “phloem” through which manufactured sugars are transported from the leaves down to the roots. When the bark is damaged or lost, the phloem can be damaged as well. That’s why it’s important that new bark form as quickly as possible. Do not cut or peel the loose bark away.

Sunscald of unprotected trunks of new trees

Bark serves to protect the internal tissues of our trees’ trunks, but as we just discussed, bark can be damaged by the elements.

Our Texas sun does a great deal of that damage, and it’s usually to species that have very thin bark while they’re young. Some of the prime candidates include oaks, pistachios and maples. When the sun is allowed to beat onto their trunks in their first couple of years in our landscapes, it’s not uncommon for the bark on the south or southwest sides of their trunks to develop extreme cracks, sometimes extending clear into the wood of the trunk.

The bark may peel off in huge chunks exposing all the tree’s internal wood to borers and decay. This is a prime reason for the loss of new Shumard red oaks, live oaks, red maples and Chinese pistachios.

So, what’s a gardener to do?

Hopefully you’ll work to prevent this rather than trying to correct it. It ought to be a rule that every new tree of those and other susceptible species have its trunk protected with paper tree wrap or some comparable covering for its first 18 to 24 months in the landscape. That way sunscald would never develop. The paper tree wrap clings to itself and can also expand as the tree’s trunk grows larger. It’s available from better nurseries and hardware stores or online.

If you have a tree that is already showing signs of sunscald it’s best just to leave it alone and keep an eye on it. Wrapping it won’t be of any help at this point and could actually offer safe harbor to insects and decay.

Time to set the binds free

We often stake and secure new trees when we plant them. That’s a method of allowing them time to grow roots out into adjacent soil so the tree can remain bolt-upright forever. That’s all a good plan, but when we forget to remove the cables a year or two later that’s when the wheels come off and our good intentions turn into a life-threatening concern for the young tree.

Here’s how the problem unfolds. We use cable or nylon rope to anchor the tree securely. As the tree grows, the trunk gets larger and expands into the cable. Since the cable doesn’t enlarge, the tree’s trunk grows around it.

As that is happening, the cable cuts into the bark, then the phloem and eventually the cambium. In doing so, it interrupts the supply of plant sugars that are manufactured in the leaves and then sent down to the roots to keep them alive. The roots die gradually, and the plant dies as well.

The takeaway from all that is that it’s fine to stake and guy a new tree, but don’t leave it in place for more than one or two years. And keep a close eye on it for any sign of girdling. Remove the cable or loosen and reposition it at first signs of a problem.

You can hear Neil Sperry on KLIF 570AM on Saturday afternoons 1-3 pm and on WBAP 820AM Sunday mornings 8-10 am. Join him at www.neilsperry.com and follow him on Facebook.