Guy LeBlanc is honored to have been named the 2012 Texas Arborist of the Year by the International Society of Arboriculture Texas chapter and the Texas A&M Forest Service. It is awarded in part for his 35 years in the tree care business, and his volunteer efforts to increase the public’s awareness of proper tree care.
The last two years have turned out to be some of the toughest of the last half-century on our central Texas trees. Last year’s drought outright killed an unusually high number. Ironically, many that have survived, especially pecans, are now breaking apart due to drought-weakened wood supporting (or more accurately, not supporting) excessively heavy branch tips and nut crops due to recent rains. For every tree service I have spoken to, 2012 has been the year of dead tree and broken branch removal.
But now what’s really making the phone ring are calls about “tree sap” making every thing sticky. These calls are mostly about pecan trees, but people with crepe myrtles and oaks are calling too. But it is not tree sap that is making a sticky mess of everything. It is a variety of insects.
Tree insect pests are very roughly divided into three categories; those that suck, those that chew, and those that bore. The class of insects causing so many problems now (summer) are the suckers, particularly aphids. They generally feed on the underside of the leaf and can be seen with the unaided eye (although accurate ID usually calls for magnification). And the sticky stuff? Well, to put it bluntly, it’s poop.
You see, aphids are kind of like many humans. They love sugar and don’t know when to stop eating. An aphid just inserts it’s sharp little drinking straw of a mouth-part into a nice, juicy leaf and keeps sucking long after the sugary tree sap is flowing out its other end. So in a way, it is tree sap. It’s just “processed”.
The one causing the most problems for pecans now is the black pecan aphid, which is common every year in Austin, but is in record numbers this year, probably in part due to the very mild winter and all the lush foliage caused by heavy spring and summer rains.
Many deciduous oaks I have looked at are having aphid problems also, including wooly aphid on post oaks, but others are having problems with another type of sucker – the lacebug. Not to be confused with the lacewing, a beneficial insect, the lace bug is a common pest of oaks and sycamores.
Other insects in the sucking family that often cause problems in Austin are spider mites, plant bugs and psyllids. Many of these sucking insects have characteristic damage patterns. The lace bugs and spider mites, for example, cause what is called stippling; a mottled fine spotting of the top surface of the leaf. This is caused by the removal of the leaf’s chlorophyll. The pecan aphid causes dark brown dead patches on pecan leaves. Other aphids and pysillids cause a curling of the leaf margin or other distortion of the leaf.
Of course, what everyone wants to know it what to do about these little suckers. The vast majority of the time I recommend doing nothing, especially if the infestation comes late in the growing season as it is this year. These deciduous trees will be losing their leaves in a few more months, and have already done a large part of their work (photosynthesis or sugar production for the plant – but that’s another blog). In fact some experts say that photosynthesis is greatly reduced in most American deciduous trees when temperatures are routinely hitting 100 degrees F.
Just like years in which we have heavy caterpillar damage (when there are no leaves left at all), a healthy tree will recuperate from this. At least with sucking insect infestations, some leaf surface is retained. Sucking insect damage does often cause premature leaf drop, but again, healthy trees will recover from this.
Another problem with aphid “honeydew”, as it is called, is that because it is so high in sugar it is a perfect substrate for mold. This frequently causes a secondary mold infestation which can turn leaves black, especially on crepe myrtles, and this can reduce photosynthesis further.
If your tree was not healthy before the infestation, or you can’t live with the mess, you may wish to treat the insects. There are a variety of things that can work. It is important to use the least toxic substance possible, not just for human safety purposes, but because you don’t want to kill the beneficial insects as well. If you wipe out the bugs that eat the pests, like ladybugs and lacewings, it can lead to a cycle of dependency on pesticides. Another irony of some high toxicity pesticides is that those used to control some sucking insects have been shown to cause an increase in populations of others, especially spider mites, which are a totally different class of bug (arachnid). Low toxicity treatments often include insecticidal soaps.
Finally, I recommend bagging and disposing of fallen leaves from infected trees. It won’t cure the problem, but it can reduce reinfestation, and can suppress certain fungal leaf diseases, which I am also seeing a lot of this year. But if your trees are healthy, fallen leaves are a valuable part of the nutrient cycle and should be mulched and left under the tree.
If your tree has not been seen by an arborist in the last year or two you should see my contact page to arrange a consultation.
Unless you were specifically looking for me, you probably came across this site while searching for tree trimming, pruning, arborist, or some other tag words, and along the way have seen or may see sites for dozens of so-called arborists. My oh my, how ever does one choose?
There are lots of variables that can help you find a competent person to provide tree care for you, but I’ll start with the word “arborist”. It may surprise you to know that unlike “doctor” or “lawyer”, there isn’t any sanctified definition of this title, or the use of it- anyone with a chainsaw and a ladder can call his or herself one. So that can be a clue right there- anyone stating or implying that they are “licensed” by the state to perform tree care is, as politicians love to say, being disingenuous.
Yet there is such a thing as a Certified Arborist. The certifying organization is the International Society of Arboriculture. They have had a national certification program in place since around 1991. In Texas, the first I.S.A. Certified Arborist exam was given in 1992. I was among the small number who took and passed that test, and I have maintained my certification ever since. Renewal requires acquiring only 30 CEU’s over a three year period; I have totalled over 700. I also teach many CEU classes.
It is important to remember that passing the Certified Arborist exam does not make one the be-all-end-all of tree knowledge. It is a test of the most basic knowledge one needs for tree care, and the prerequisites for being able to take the exam could include having planted flowers for a living (not that anything is wrong with that). So there are some very smart people with pretty much no tree care experience who have passed the exam, and a lot of not-so-smart ones with lots of experience doing tree care really poorly. So don’t let this be your only qualifier.
It is also important to know that most tree services in Austin do not have Certified Arborists actually performing the work they sell. Often a company has a Certified Arborist as its owner, salesperson or foreman, and the people actually doing the work were digging ditches the month before (not that anything is wrong with that). You’re better off hiring a company in which Certified Arborists actually do the work, like mine. And don’t be confused by the Certified Tree Worker designation (which I also have). This certification focuses more on basic climbing skills, not arboricultural knowledge. While it is admirable for a company to certify its employees, it is by no means an assurance that the consumer will receive quality work.
It’s important to make sure that persons working on your property have an adequate amount of quality experience to back up their certification. I recommend a minimum of 20 years for the owner or manager of your account and 7 years for those actually doing the work. Yes, there are many with less experience that are quite competent, but the chances of getting an incompetent one (or worse) are higher with less experience.
Insurance is another factor to consider. All competent tree services in Austin carry appropriate insurance. This means general liability insurance, personal injury insurance for owners and workers compensation for employees. It may surprise you to know that none of these are required by law in the state of Texas. Just to be clear, remember that having these insurances is not a guarantee of quality work.
But any company that does carry insurance will be happy to show you proof. Just remember, you should verify that the policy is in force. We had a case in Austin some years ago where the city hired a tree company that actually provided a completely bogus insurance certificate to the city. Your tax dollars at work…
Be especially wary of memberships. My personal experience is that the more prominently a company advertises memberships, in the Better Business Bureau for example, the less likely they are to be a quality operation. The BBB has absolutely no enforcement power, and has little incentive to punish a paying member. Likewise, memberships in tree associations like I.S.A. or T.C.I.A., without accompanying certifications or accreditation, mean nothing more than that someone paid an annual fee to use the group’s logo. I have seen several tree companies in Austin over the years advertise membership in organizations that don’t even exist!
Finally, check the arborist’s work. You can become familiar with what proper tree care is by reading about pruning on my website, and ask for and verify references. Obviously, a company isn’t going to tell you about people who have been dissatisfied with their work, and internet referral sites are laden with misinformation (both pro and con), but if you take the time to become familiar with what a properly pruned tree should look like (it’s not rocket science), you can look at a few dozen trees and tell whether they have been pruned well or not.
Or just make it easy on yourself. Hire Guy LeBlanc!
Last year’s record heat and drought compounded the severe impact that the 2009 drought had on trees in Austin, Texas. In 2009 we saw record levels of dead and declining trees due to drought. The heavy rains that occurred that fall and into 2010 were not enough to save many of the trees that initially survived.
The same thing is happening now. The heavy rains of this winter were not enough to save many of the trees that survived through 2011′s drought. Now that the late-blooming species are in leaf, what is dead is apparent, and the phones at tree care services around town are really ringing.
My business is about tree care, not about being a “tree mortician”. I have focused my 30-plus year career on maintaining trees and advising property owners on what they can do to preserve their trees. This means pruning, cabling, fertilizing, and other tree care techniques. I can certainly perform difficult removals, but they are not a satisfying thing for a highly experienced Certified Arborist.
So, what can one do for a drought stressed tree? Well, the short answer is, unfortunately not much. If there is substantial dieback, nothing is going to bring those dead limbs back to life. Now that almost every live tree in Austin is in leaf, if it doesn’t have leaves, it’s very likely dead. Once you know for certain that a large limb is dead, it should be removed quickly. This is for safety purposes. Some species shed their dead branches much more quickly than others. Pecan for instance can shed large dead limbs within a year, whereas live oak will often hang on to them for many years. Dead limbs really aren’t a health issue for trees in the short term (less than a year).
Some tree services recommend fertilization for trees affected by drought. Although fertilizing has its place, I do not automatically recommend this. In fact, fertilizing can be harmful to a tree in a severely stressed condition. Fertilization should only be used when there is a known nutrient deficiency. This is something I always assess before considering the addition of nutrients.
The best approach to trees stressed by drought is to maintain proper irrigation levels and improve soil quality. Soil improvement is largely done through the addition of organic materials to existing soils, but more aggressive mechanical means (such as an air spade) are sometimes employed for extremely poor soils. As with fertilizing, there are right ways and wrong ways to improve soils.
Proper irrigation can be achieved for trees even under most stages of city water restrictions. I generally recommend a thorough soaking about once a week during the hottest months. How much time and water that will take will depend on your specific irrigation system, water pressure and soil type. A heavy soak once a week is far preferable to multiple short waterings per week. If you have a thick turf like St. Augustine grass, you may not even get much water through it and to the tree roots if you are doing short waterings, so in this situation your tree could still suffer drought stress even if you were watering every other day. I can discuss the specifics of how to best achieve these things on your property during a consultation.
Another big problem that trees stressed by drought often experience is borer insect infestation. Although some aggressive species of borers can attack (and kill) healthy trees, most are opportunistic, and are more likely to attack stressed trees, and some species are more susceptible than others. While chemical treatment of these insects is possible and sometimes necessary, often the infestation is only noticed after the insect has already damaged the tree and is no longer present. Correcting the stress factor is usually the best approach.
If you have trees that are in need of tree care, you will get the best results from a tree service in which the treatment is personally provided by an owner/operator who is an I.S.A. Certified Arborist with at least 15 years of local experience such as mine. I have owned and operated Arbor Vitae Tree Care for 29 years.
Warm weather will soon be returning to central Texas, which means folks here will soon be thinking about pruning their trees and other aspects of tree care. A common question that comes up now is, “What about oak wilt?” For years, it has been recommended by government agencies to avoid pruning oaks in the spring because of a perceived increase in the risk of getting oak wilt. What is the reality of pruning oaks while minimizing the risk of this deadly fungus?
About a year ago, I chaired a group of arborists from the Texas chapter of the International Society of Arboriculture, the Texas Forest Service, and Texas AgriLife Extension Service which clarified the existing guidelines. This was to explain to the public that certain kinds of pruning can be done year-round on oaks. This would include removing dead branches, and branches at risk of being hit by vehicles over streets, and those rubbing against buildings or other branches within the canopy. For details on this, see my oak wilt page. You can also see a Central Texas Gardener video of me explaining oak pruning and oak wilt on YouTube. To read the statement in its entirety, do a web search for “pruning guidelines for prevention of oak wilt in Texas” and “Guy LeBlanc”.
Oak wilt has been in the news locally for so long (in Austin it almost created hysteria in the early 80′s) that I sometimes forget that most homeowners don’t really know much about it. In brief, it is caused by a fungus very closely related to the Dutch Elm disease fungus which many folks from northern U.S. are all too familiar with. It only affects oaks (and tanoaks). The disease spreads in two primary ways. The majority of the spread of the disease (95% of it according to one researcher) occurs underground due to the propensity of live oaks to form grafts (actual vascular connections) between the roots of different trees. Live oaks also occur in groups called motts, which means that all of the trees in the group have formed from root sprouts. Motts are also therefore interconnected and the disease spreads quite readily through them.
The disease can also spread above ground, creating new infection centers. This occurs when vectors (in this case a beetle called the nitidulid is most likely the culprit) visit the fungal spore patches (called mats) on infected trees and then carry those spores to fresh open wounds on healthy trees. In Texas these mats only form on red oaks, never on live oaks, so it is important to remove dead red oaks immediately- in fact in Austin, there is an ordinance requiring any property owner to do so.
It is believed that the nitidulid is attracted to both the odor of the mats, which have a fruity-licious smell, and the odor of fresh sap from new wounds. The highest levels of this insect population and the creation of fungal mats coincide only when weather conditions are just right, which is usually in the spring. This is why government agencies have recommended avoiding pruning in the spring.
However, we also know that very often in spring the weather conditions are not conducive to the development of the fungal spores (too hot and/or dry). No spores = no above ground spread. Or it can be too cold for the insects to be active (last year it was in the 20′s for 3 days at the end of Feb). We also know that painting wounds provides a nearly total barrier against spore invasion. There is no published scientific study in which painted wounds contracted oak wilt (one study in 2007 seemed to contradict this, but it was found that the trees were becoming infected underground). We also know that dead tissue cannot be an invasion point for the spores, so removing completely dead branches never exposes a tree to oak wilt; technically, dead tissue doesn’t even have to be painted, however, I usually paint it just in case some live tissue is present on part of the wound face.
The bottom line is that while oak wilt is often fatal, the actual risk of contracting it through open wounds, even in the spring, is minimal. If it wasn’t we probably wouldn’t have any oaks left, as wind, hail and animals such as squirrels and birds cause extensive wounding, often in the spring. And this risk can be actually be reduced if the pruning is done by a competent professional - which is of course the only type of person you would ever let touch your trees!