Trees and Hurricanes

Hurricane Irene was not kind to the trees in Onslow County.  During my post-storm inspection of the county I noticed a lot of trees that were down or damaged to the extent that they needed to be removed.  However, it was interesting to note that the majority of the damage was limited to a very small number of tree species.  Bradford pears and pecan trees definitely bore the brunt of the damage but there were a smattering of water oaks down as well. 

So what do we do now?  Many people are afraid of any tree in a hurricane but it is obvious that some tree species withstand these high wind events much better than others.  The University of Florida (UF) has done extensive research on tree survival in hurricanes.  This study looked at many factors that related to tree survival in hurricanes but today we are going to look at just one factor: species selection.  Some tree species are simply more resistant to wind than others.  It would be wise to take this fact into consideration when choosing trees for your property. 

Good trees for our area that show the highest level wind resistance based on this study include: American holly, yaupon holly, crape myrtle, southern magnolia, live oak, bald cypress, pond cypress, and sabal palm.  Those rated medium-high for wind resistance include: Japanese maple, river birch, ironwood, sweet bay magnolia, shumard oak and hickories.  Consider using these species to reduce future storm damage potential on your property.

Equally important to note is which trees fared most poorly in the UF study.  Common local landscape trees that showed the lowest wind resistance include: pecan, tulip poplar, Bradford pear, southern red, laurel and water oaks, Chinese elm, and Leyland cypress.  These species should be avoided in landscape plantings.  Pecans should be situated well away from structures and power lines.  Likewise, red and silver maples, sycamore, white and willow oaks, weeping willow, and American elm scored medium-low wind resistance so avoid these as well or use them only with caution. 

We will discuss how to assess a storm-damaged tree and other factors relating to hurricane-survival in future posts.  Meanwhile for more information about hurricanes and trees, check out the University of Florida’s site Trees and Hurricanes here http://hort.ifas.ufl.edu/treesandhurricanes/. 

Slime Flux or Wet Wood

Several weeks ago, I had a very interesting home visit.  A woman told me that the sap was bubbling out of the base of her tree.  When I arrived, the sap was indeed bubbling out of the base of a mature oak tree.  It was bubbling along so quickly it made me think of a pot simmering on the stove.  There was a strong wine-grape smell in the air as well.  The sap was attracting a lot of green June beetles and an assortment of wasps and bees.  This is what I saw:

When I pried some of the outer bark off, the inner bark was soft and spongy:

After a little research, I found out that this a bacterial disease called "slime flux" or "wet wood".  Slime flux is a bacterial disease common in large, mature landscape oaks, tulip poplars and elms.  Bacteria carry out fermentation under the bark of the tree and produce carbon dioxide gas in the process.  The gas forces sap out of the bark under pressure - hence the bubbling. 

Slime flux isn't a serious problem if the tree is otherwise healthy.  These is no cure or prevention for slime flux other than maintaining trees in good health and minimizing wounds or injuries.If there is lose or dead bark in the affected area, remove the loose bark and allow the area to air dry.  Do not apply any sort of wound dressing.


You can learn more about slime flux here:
http://www.ces.ncsu.edu/depts/pp/notes/oldnotes/od8.html

Bradford Pears Blooming Out of Season

In my last email, I mentioned that a lot of bradford pears damaged by Hurricane Irene are reblooming now.  Blooming out of season is a normal response of plants that have been stressed.  This storm left behind an interesting phenomena - many of the affected trees are blooming only on the windward side.  This is same side that they lost most of the their leaves on during the hurricane.  The loss of leaves triggers a hormone response that promotes flowering.  The tree shown above is a perfect example - this tree is in front of the public library in Richlands.  

As long as these trees haven't lost large limbs, they will probably recover well over the longterm.  You may see some decrease in bloom next spring if your tree is blooming this fall.  I have also seen some cherry trees and azalea shrubs reblooming.
 

Fairy Ring

Rings of mushrooms may crop up after rain in the fall.  These rings are referred to as “fairy rings”.  The mushrooms are the fruiting bodies of a larger fungus that is growing in the ground.  Generally fairy rings only pose an aesthetic issue in home lawns.  Frequent moving will remove the mushrooms or you can knock them over with your foot as you see them coming up.  Over time, the fungus in the soil may make the soil resistant to water infiltration.  If grass starts to brown around the ring, frequent regular aeration (with a plug aerator or the tines of a pitch fork) will help promote water infiltration, soil rewetting and grass survival. 

Dividing Perennials

Dividing perennials is an enjoyable garden task that promotes plant growth while allowing you to create more plants in an easy, low-maintenance way.  Vigorously growing perennials like chrysanthemums and asters may need to be divided every season or two, while slower growing plants may never need to be divided except to propagate them.

Many perennial plants benefit from regular division but don’t divide on a time schedule, let the plant’s growth habit dictate whether you need to divide it.  Perennials need to be divided when: flowering is reduced or flowers get smaller, the center growth dies out but there is growth around the edges, bottom foliage is sparse, the plant loses vigor, the plant flops over or requires staking or it has simply gotten too large for its space in the garden.  Of course, even if your plant is growing and blooming well, you may choose to divide it to create more plants for your garden or to share with friends.    

Perennials should not be divided while they are in flower; flowering demands a lot of energy from the plant and you do not want to stress a plant by dividing it at the same time.  The general rule of thumb is to divide spring-flowering plants in the fall and fall-flowering plants in the spring.  Fall division should take place early enough that the plant has at least 4 to 6 weeks to establish roots before the ground freezes.  Spring divisions should be carried out early enough that the plant establishes new roots before hot weather sets in.

Prepare ahead of time.  Water your plants thoroughly a day or two before you plan to divide them and prepare the area that you plan to put your new divisions in.  You want to minimize the amount of time that the plants’ roots are out and exposed to the air.  If appropriate, prune the stems and foliage down to about 6 inches from the crown to ease division and cut down on moisture loss. 

Use a sharp pointed shovel or a spading fork to dig down and lift the plant or section of plant.  You will want to dig down all around the plant about 4 to 6 inches away from the base.  Slide your tool underneath the root mass and lift the clump out.  Shake loose soil off the root ball and remove any dead leaves or stems.

Division of the clump will depend on the growth habit of the plant you are dividing.  For any plant, remember that you need to maintain a portion of the growing point (crown) and a portion of the root system intact. 

Some plants can easily by divided by teasing the root system apart and separating the crowns by hand.  If the clump is more substantial, you may need to use two digging forks placed back to back to pull the crowns apart.  In some cases, you may need to divide the clump by cutting with a sharp heavy knife or handsaw.  Work your knife between the crowns and cut down through the clump and root ball making sure that each crown has a healthy portion of root attached.  Likewise, a sharp pointed shovel can be worked between the crowns and used to cut down through the root clump.  Whatever technique or tool you use, make sure each division contains at least 3 to 5 shoots.

Never allow your divisions to dry out.  Keep a bucket of water close by to keep them moistened until planting.  Prune off any broken or damaged roots prior to planting.  Plant your new divisions immediately in the prepared garden bed or in containers with a clean, coarse potting mix.  Plant divisions at the same depth that they were growing originally.  Firm the soil around the roots and water well after planting.  New divisions should be watched carefully and protected from drying out until the root system is well established. 

Not all plants benefit from division.  Butterflyweed, euphorbias, oriental poppies, Japanese anemones, and false indigo are all examples of plants that should not be divided.  Likewise, many woody plants don’t divide well.  Instead, look for a branch that has naturally layered near the base of the plant.  This can be dug up and replanted instead.