Fall colors on Trees

Here in Montgomery County and everywhere in Southeast Texas, we begin a little bit later than in the north to see fall colors. Sometimes, we see almost nothing at all except for the Chinese Tallow which is considered an invasive species and outlawed from trees nursery sale inventories. That tree is very ornamental in the fall, one trait that brought its popularity in the past century. In reality, this is not a place for a fall showing of trees, but sometimes it really surprises me what the native trees will do. Technically the Fall season has arrived, but it will be a while before the trees think it has arrived due to our southern position.

What causes the differences we see each year? It is the weather, pure and simple. Rain while the leaves become deprived of nutrients is a key component in determining the colors. The sugar content of a leaf is very important to its coloration and brilliance. If we get an early frost, the leaves are more likely to drop as ugly dried brown leaves than colored leaves, although it depends on the species and the moisture as well. Because we have had a near average rainfall this year, I am expecting a better fall show in this area. We have a fairly large population of native hardwoods interlaced among the evergreens, enough to give us a spectacular show when the conditions are right. I have seen a few trees already beginning to have fall colors, even though it is very hot. Too much heat can offset the beauty  given by the water. If we do not receive much rain and the heat stays with us, fall will again just be a blink of the eye. We need long and cool night with some light rain. More details can be found in this link: Explanation of Fall coloring

USDA Forest Service reports the fall colors for all national parks at this link. This may give insight into what is happening as the fall unfolds in the southeast. 

Bald Cypress in The Woodlands

Cypress trees are found here on ponds, creek beds and lowlands. I have planted many on the pond near our home in The Woodlands, Texas. Talk about slow growing! Talk about living to be old! They can be 800+ years old. These trees do their best in wet but fertile soil as one would expect. The soil on the banks of the nearby pond is not very nutrient rich. In fact is is heavy clay. Our 8 year tree has been pruned several times, not by us but by people who do not appreciate what it takes to grow one of these. We have one in our backyard that is doing very well and is turning into a fruit bearing tree this year after about 7 years of growth from a small sapling. It must now be about 12 feet tall.  Notice the low hanging branches. These often provide protection for deer and other creatures during the day in the forest. It also provides shade for fish in the water. The knees grow in water and land. Is is speculated that they enable the plant to get oxygen when the roots are submerged, but I have my doubts that anything of that sort is important to the tree. I suspect it has something else to do with survival in the water. 



Viewing the fruit, one is led to believe that this might be edible. Wrong! The tree is a conifer.  These little balls turn into a plated cone, like a pine tree and sends seeds into the air for sprouting new trees. Right now the fruit is very pretty on the tree. This happens to be our maturing Cypress of about 12 feet.

Another interesting characteristic of this tree is its shedding of leaves. It does this in the late fall and dry summer. That seems to protect it from severe weather. It sprouts new leaves when the rains come and turns green again. It is not hardy when it comes to fire. Several of the ones I planted were exposed to fire and did nto come back. Some did, leafing out from the roots but not the burned trunks.

Woodlands Forest Understory Wins One

The residents in The Woodlands Texas won over the development  company in some conservation of forest last night at the Sterling Ridge Village Association Meeting. Joel Deretchin brought some good news to those who were concerned about losing vegetation which shielded their homes from view. Yaupon is too often thought of as a trash tree. It provides important berries for birds and wildlife, as well as provides the undergrowth to help protect our large trees. A forest is not a tree and a tree is not a forest. To save the forest, we must also retain the understory, not just retain the large diameter trees, but the full forest of canopy and understory.

A green area in the Tarramont Park area shields homes on the golf course from traffic, giving the residents their privacy. The Woodlands Development Company decided to remove it without talking to residents, to provide a view of the golf course from the road.  After a few residents observed the activity, more came to an awareness of this project. Many residents expressed concern and became very outspoken on the issue. The Development Company stopped the project and formulated a plan that hopefully will include the residents on future clearing projects.  They will replace that which they removed and leave the green area in place.

After a certain point in development, the company needs to include residents on anything they do. This type of issue has risen many times. After people invest in properties, they have a large stake in further development and changes about them. The development company has the responsibility to include them in future decisions to change green areas. The Yaupon and other understory species are an important part of our forest. We need more sensitivity of their presence and role.  Green areas are important to residents. There are proven psychological and value advantages for having the full diversity forest in our midst.

As the people in the room clapped, I could see an element of surprise on the face of Mr Deretchin. This was much more important than the development company realized. It is also a lesson on general policy of inclusion of residents. It had the potential of blowing up and being blasted out to the news media with a red flag of resident investment risk.  

Spring has sprung even before winter is over - seeds of the elm

One of the first trees to recognize that Spring is here is the Elm. It blooms and sows its seeds before most trees even show buds for flowers. This happens right at Valentines each year.In the sunlight, the seeds can appear magnificent, and putting a light through them, one can see how they will be blown about by the wind and establish themselves far away. I have dozens of them coming up in the yard every year. A very prolific tree which migrating birds love. The leaves don't begin to appear until the seeds start to fall. Such an amazing tree!

One more summer gone, many tree years gone, Winter's Respite

There remain a number of trees to cut down after the terrible loss we had this past year with beetles in our pines. Based on what I saw, the 1000+ trees that had to be removed from public areas along roads, paths, parks and medians, most of the trees were older than 10 years. Many were 30+ years old. Let's just say conservatively, they were each ten years old on the average. That would present us with a 10000-year tree-year growth loss. I could not say what number of tree years we have in our forest, but it is a very very large number, so the percentage of loss remains fairly low. Yet intuitively, none of us can rest peacefully with the results. The primary reason we must not just write this off is the mere fact that there is a forecast for ensuing years of continuing and even worse drought. Then too, we lost a large number of trees in 2008 to the hurricane. The combined two events raise our alarm to a higher level than the norm.

How are we going to deal with rain shortages, water conservation and preserving our trees at the same time? We must put some financial resources into our future. If this year is only a taste of the future, we should be doing something about it and not just let nature take its own natural course. The one valued commodity that we have, unique from other communities, is our large trees. Without them, we are just another large subdivision on the outskirts of Houston - waterway or not, parks or not, nice homes or not. Nothing really matters except our trees.

Woodlands Pine Trees - we are losing the battle. Now Pine Bark Beetles!

Pine bark Beetles are having a field day, because our pines are weak from the 2009 Texas drought. As you travel about in The Woodlands and Southeast Texas forests, you will see dying or dead trees. A dying tree is turning brown, typically from the bottom limbs towards the top, whereas a completely dead tree has no green leaves at all. The water delivery system has been cut off. Sometimes one, sometimes several trees are dead in a "stand" of trees. One business I visited just today had a problem with this insect. Someone from the Association had already been there to advise the business to remove the infected trees as quickly as possible. That business planned to cut them down this evening. I inspected the trees and discussed the issue with the manager. One tree dead, one adjacent tree dying and two more infected. In that these beetle attacks are classic, by the book, I believe they will lose all four trees. They have already received a guide on what species of trees are recommended to replace those they are losing. These beetles are slowly killing our mature trees and those not so mature. Since it takes decades for a tree to reach 50 feet in height, we are losing what we prize as our trademark - the pine forest trees. It is happening to all species but the Loblolly tends to be more adaptive to the beetle than the Shortleaf or Longleaf. It is not difficult to identify a tree that has been infected. On my street alone, we have lost three large pines this year to the beetle. I have seen three other pines lost in our neighborhood and several others in the park nearby.

This Woodlands tree to the right, infested with these insects, appears to have the pox. A bubbly mass of sap and a bit of the drilled out cambium layer shields ants and other intruders, like woodpeckers from the tunnels built for their eggs and subsequent larvae. The result is a nice tube cavity suitable for eggs to develop and which can be expanded by the young as they mature. This insect deprives a tree from water when many of the insects attack simultaneously. Since the beetle can explore, attack and finish their reproduction cycle in a matter of a few days, they accomplish  complete tree destruction by their numbers and can carry on their attack to a full stand of trees in one summer. Their life cycle is very interesting. One beetle will serve as an "explorer". He finds a tree, bores into it and when he is able to reach the inner layer, he excretes a chemical that attracts other beetles. Hundreds can be drawn to one tree and they can collectively kill the tree to make a nice habitat for their offspring. The eggs hatch under the bark in the incubation tube and the cambium under the bark serves as food for the hatched larvae. The larva then changes into a pupa.

This ugly little thing is a live larva, found under the bark and beneath the inner bark layer of an infected tree here in The Woodlands. If you recall your biology, you know the pupa of a beetle is equivalent to the worm stage of a butterfly. The larva stage of the beetle is equivalent to the worm stage of a butterfly. Instead of eating leaves, this beetle eats the cambium or the live part of the tree trunk, the part that creates the outer ring of wood and the inner bark.

This is the area of the tree from which the pupa was extracted. You can see the bark (outer layer), the cambium (orange second layer which has living cells) and the wood (light brown inner layer). The cambium is the food for the larvae and pupae.

This is the adult, courtesy of  the University of Georgia Bugwood Network.

A stand of infected trees (or perhaps better stated "trees under attack)", is on the Woodlands Parkway. Two trees are dead and two adjacent trees are now under attack. Since it takes about 8 days to kill a tree, this will be completed in only one more week. Then others will get infected unless these are removed now.

Some interesting facts about the beetle: they do not die off in the winter. They tend to attack the same tree several times over, but their lifecycle is slower than it\ is in the summer. The insect is active all year long. Adults will lay eggs and leave their eggs host to attack another tree, but they will also reemerge and lay eggs in a tree previously attacked, even using the same tube. They lay about 30 eggs per mating sequence. They do have enemies - the woodpecker, mites,  and two types of beetles. I am reasonably sure I saw a Checkered Beetle on a tree infested with the Pine Bark Beetle.

When inspecting trees, one will find another visual hint of an infection, the running of sap such as you see on the right. Inside the bark, there are probably pupae causing the flow of sap to flow out of the tree instead of up water moving up the tree.

You might also see this - the powdery cuttings of the inner bark or outer cambium.

How does one treat this problem? Unfortunately, the remedy is very difficult. Generally, in forest management, the trees are cut down and isolated from others in a stand.  They can be allowed to stay or burned.. At a residence or park, there may be insecticide remedies or natural predator remedies but the insect attacks are so quick and  thorough, there may not be enough time to react. Prevention measures against a flying insect is not very promising. At the time of writing this article, I have not ascertained the best approach, although I would prefer to take the natural predator avenue. This is the next step in my study. I believe it is best to get this concise information to readers in order to educate what might be happening in their piece if the forest.

On September 26th, I visited a booth of the Forest Forest Service. We discussed this problem and the following is from my learning there. The forest service is currently inundated with concerns from all over the state. A prolonged drought weakens our pines to the extent that they become not only vulnerable to the beetles but are significantly at risk of death. This year has been a very bad year for the IPS Bark Beetle. This species attacks the weak trees and does it in stands or groups close together, unlike the Souther Pine Beetle and turpentine beetle, which attack healthy trees and takes out one at a time here and there, not typically in stands. A tree infected with the engraver beetles will often have three IPS species in it. The six-spined calligraphus is the largest at 5mm and attacks the large diameter portion of the tree - trunk and limbs. The eastern five-spined grandicollis is the mid sized at 4mm and attacks the smaller branches in the mid part of the tree. The smallest at 3mm is the southern avulsus which attacks the small branches, typically at the top or the furthest from the root system, in recent growth parts of a tree.  One species at the base, one in the center and another in the top. Our trees in The Woodlands are susceptible, because they typically grow in shallow soils with a clay layer beneath it, making the soil not give up the water that the tree needs in a drought.  Typically the IPS Beetle, also called the "engraver", is 3-5 mm in length. The other beetle now active in the forest is the black turpentine beetle, a lover of fresh pine sap and thereby the name. They however are typically found in stumps and injured trees usually associated with logging but in our case, with the injuries from hurricane Ike.²  
It is important to note that a home owner could have a healthy tree and three days later the tree could be dying from these beetles. The engraver beetles act fast and in mass!

Although we are not going into treatment in this article, the advice was - give the tree masses amount of water as soon as it sees the problem. A lot of water will also help your trees through very stressful times in a prolonged drought. Another piece of advice is to keep the areas around a pine tree free from fresh cuttings. Do not cut your trees and place the cuttings under the tree. Remove fallen live branches from pines, thereby removing the attractive material that initially brings the beetle under your tree.

Every year we have this issue with beetles but this one is particularly tough because of the hurricane and the drought. We typically see cycles of infestations. Expect the southern pine bark beetle to emerge in big numbers in a few years. They typically follow a major infestation of the engraver beetles about five years afterward.  The last really bad infestation of that beetle was in 1985 when 15000 infestations were reported (note that this was the number of event reported, not the number of trees - one infestation might cover 100 acres or more).  

What has happened is that hurricane Ike produced a lot of material on the ground that the beetle could feed on and that attracts it. In the Spring, the material was available but as the summer drought unfolded, the beetles needed to get their nutrition from the live trees. Once an explorer finds a vulnerable tree, he chemically calls the others and bingo! There is an infestation attracting all species of the engraver beetle and possibly other species as well. Thanks to the representatives from the forest service for their valued input to this article.

References
1. Bark Beetles of Concern to the Southern U.S. by the University of Georgia Bugwood Network
² Southern Pine Beetle or Pine Engraver or IPS Beetle, a brochure by the Texas Forest Service

How to water trees during a drought in Southeast Texas

This article applies to any drought-stricken area including Southeast Texas, especially The Woodlands Texas. Anyone who knows me, knows I love trees. It is time to be concerned about this year's drought. This year could be a record breaker! That is, this could go down as the worse year in history for a summer dry spell. La Nina is the key. When will it go away? Next hurricane? Regardless of the answer, we need to water our trees now. Two months have passed without significant rainfall.

Any tree planted within the last two years must be watered now. My suggestion is to water a small tree thoroughly every two weeks. Trees that have been planted more than two years ago may need attention now also. They can be watered every three weeks. Very large trees can generally get away without water for four weeks but be careful. One formula for application volume is 10 gallons per inch diameter of tree trunk. The temperature is so high now (100+ degrees) that all plants need more frequent watering than they normally require. To water trees, it is advantageous to understand where the roots are located, the physical nature of the roots and water delivery process to the leaves.

How do leaves get water?
A tree's primary source of water is an area from the surface to about a foot and a half deep, located around the tree. To understand what the root system looks like, simply look at the tree and picture the tree limbs as roots which are usually a mirror image of the tree limbs. The length of the roots will be longer than it corresponding limb and will extend beyond the drip line of the leaves. Now think of the leaves as fine roots needing to find water. The tap root will penetrate much further, but the shallower roots are its source of life and are the key to the tree's health. 90%+ of the roots of a tree are within the first foot of soil! In broadleafed trees, water is delivered to the leaves of the tree from the roots by a physical process called transpiration which leverages a basic physics process called capillary pressure. A pressure that counteracts gravity pull is produced by the capillary walls consisting of cells especially made to move water and nutrients from the soil to the leaves. In the leaves, during the day, the stomata under the leaves constrict to preserve water. But as inevitable evaporation occurs in the heat, water must be replaced by the capillary pressure pushing the water into the tree leaves, keeping a pressure in the capillaries. Without water in the root system, the capillary pressure can fail, causing the tree to die. The first sign of lack of pressure in the capillary system is the wilting of the leaves, next a browning, and then a total failure of the capillary system. A pine tree is different. It moves water from live cell to live cell, using a pass-the-baton type process. It is much slower than the capillary process, so pine trees die easier when the water dries up. By the time the leaves turn color on a pine tree, it is too late to recover. Pine and Cypress trees react to a shortage of water in the heat by shedding many of its leaves, thereby reducing its consumption and thirst.

How to water your trees

So as the soil dries, the process of moving water up the trunk of the tree to the limbs is diminished, stressing a tree in its ability to cope with drought. The tree needs your help. A small tree can get by with watering every 2-4 weeks. I use a two gallon bucket. One bucketful for a seedling, two bucketfuls for a 3 foot tree and three bucketfuls for a 10 foot tree. One recommendation is to provide a tree with 10 gallons per caliper (diameter) inch. To do this effectively, you must have the base of the tree mulched as an shallow upside down bowl structure so that the water is held within the irrigation area intended. Get the water to the area on the ground that mirrors the ends of the branches. This is where the ends of the roots occur below the ground. The base of the tree needs to be mulched to conserve evaporation from the ground. The larger the tree and the older age of a tree makes the process more difficult. A large tree needs considerably more water and it must be delivered slowly. A drip hose wrapped in concentric circles around the tree will soak the ground. That is the best way to make sure water reaches one full foot below the surface. It may be more advantageous to use a needle approach however for the large trees, where the water is delivered directly to the roots a foot underground. A water measurement device to one foot deep is handy for you to know if you have reached the depth intended. One can also purchase watering devices for trees at any tree nursery, but they are not required.

Conserving water and being a good neighbor

When the time comes to water trees, we almost always are under a water alert from our water utility for watering lawns. We are either asked to voluntarily conserve water or required to water the lawn only on prescribed days in order to maintain water pressure to homes and have emergency water in case of fire. Drip watering devices do not utilize a lot of water and therefore are not a threat to the water pressure if used with low pressure. However, it is wise to monitor the consumption of your watering process by taking a water meter reading before and after you have watered a tree, so that you understand how much water you are using and what the delivery rate is. If the usage is more than about 10 gallons per hour, you should not be drip watering on days that your home is not allowed to water the lawn.

Watering your lawn is not the way to deliver water to your trees, unless they are seedlings and even that is insufficient for seedlings. If you water your lawn and do not water your trees, the root system will die at normal feeder root depths and only live on the very surface. High wind can then blow your tree down much easier! One inch of water on a lawn is a significant watering but will not reach very deep for a tree's use. Remember Hurricane Ike!

Take care of your trees. They take decades to grow back. The loss of deep roots has proven to be a significant risk to homes and fences in high winds. I recommend reading the references below for additional information.

Additional Resources

¹ Architecture of a tree
² Caring for Trees During Drought