Sunday, October 27, 2013

What big thorns you have.

Have you ever noticed the thorns on a honey locust and thought to yourself 'what's goin' on with those big daggum thorns?'  Honey locust evolved along side the Pleistocene megafauna.  Extinct animals such as woolly mammoths, mastodons, and giant sloths used to roam North America, and likely fed on the seeds of honey locusts and water locusts.  
These trees depend upon large mammals eating their seeds and passing them through their gastrointestinal tract out as a way of dispersal.  But inviting a 5-ton animal to dinner can be dangerous, thus the reason for thorns that can be 8-inches long.  The prehistoric mammal gets a meal, the tree's seeds are spread, and the thorns keep the dinner guest far enough away from the tree so it can survive to make another crop of seeds next season.

Next time you see a honey locust just imagine, one of it's ancestors probably grew because a woolly mammoth pooped it out somewhere.

Honey locust thorns, they'll take your eye out.

Sunday, October 20, 2013

The Band, a spray alternative.

When controlling pests on trees and shrubs we often think of spraying some kind of chemical product, and while this is often our only course of action, for some pests there are alternatives.  Many pests can be physically removed.  Webworms and tent caterpillar nests can be pruned out or destroyed.  White peach/prunicolia scale can be scrubbed off the stems of small cherry laurels and lilacs.
Another non-chemical method for preventing pest injury to trees is creating a physical barrier.  This is most effective against certain species of lepidoptera that climb from the ground in to the canopies of trees to feed or lay eggs.  In the Charlotte, NC metro area there's an unprecedentedly large population of fall cankerworms (Alsophila pometaria).  There are many theories as to why cankerworm numbers are so large, but no doubt part of the problem lies within the overwhelming number of mature willow oaks (Quecus phellos) lining streets and gracing private yards.  
Cankerworm adults emerge from the ground after the 1st series of cold nights (at or below freezing) in the late fall/early winter.  The adult female cankerworm doesn't have wings, and is forced to climb up the trunk into the canopy of a tree to mate and lay eggs.  Each female can lay  between 100-200 eggs.  In spring, just as leaves are approaching full expansion, the little inching cankerworms emerge from their eggs and feed on the tender young foliage.
These cankerworms are present in such damaging numbers that the city of Charlotte, and most of her residents, habitually affix bands covered or lined with sticky stuff to trees throughout the fall.  This way cankerworms are controlled safely and economically.

Heartwood Tree Service Arborist affixing 'Bug Barrier' to the trunk of a willow oak.

Sunday, October 6, 2013

Is it over reacting?

Trees respond to damage or decay by forming reaction wood.  The placement and extent of reaction wood can be telling of where and how long the tree has been affected by decay.  When we think about a tree responding to decay organisms,  most often our first thought is the compartmentalization of decay in trees (CODIT) model.  However, the CODIT model is based upon a tree's reaction to damage to the bark and cambium.  When decay enters from the tree's structural root system, or perhaps an old tap root that has died off, trees react a little differently since the decay organism is growing in duramen (heartwood) tissue, which is effectively dead structural tissue.

The root flare of the willow oak pictured below has been quite disfigured by years of attempting to out grow Inonotus dryadeus and Ganoderma lucidum.  When sampled with an IML-Resistograph, what appears to be a substantial amount of wood reveals areas and pockets of substantial decay.