ROOT GRAFTING

 

KEEP TREES FREE OF DISEASES BY TAKING CARE OF THEM FROM THE START.

Trees give us so much, oxygen, shade, beauty, shelter and value to our

property, it makes good sense to do all we can to protect our trees from harm. 

 

ROOT GRAFTING of plant tissue, either stem or root tissue,        

implies an anatomical fusion between two plants or non-joined parts of the same plant which were not previously connected. Thus, if a root graft has occurred using the above definition, then whatever nutrients, plant growth hormones, plant metabolites, pathogens, assimilates, etc. can move through the plant species through transport in the xylem tissue or translocation in the phloem tissue, should move through the root graft. There are ample published research findings that demonstrate transfer of fungi (oak wilt and Dutch elm disease), herbicides (non-treated trees dies from flashback of chemical through root graft), and metabolites (girdled trees survived for years presumably form root graft transfer) through root grafts.

 

Click of Photos to Enlarge

A Pecan tree that has formed callus tissue over a Live oak limb. The Live oak tree and limb are very much alive,
 producing acorns and not pecans.                                                                                      Photos by Jim Rediker

 

The fungus that causes oak wilt, Ceratocystic fagacearum, is native to the United States. It affects both the group of trees call "red oaks" (The Live oak and Spanish oak or Texas Red oak ) and the "white oak" group (species include Bur oak, Chinquapin, Monterey oak, Lacey oak and the Post oak). Red oaks are the most susceptible to the disease and usually die within the season that they are infected.  White oaks are more tolerant or resistant of the infection due to compartmentalization or water proofing from one cell to the next, in red oaks there is osmosis between the cells.  HOWEVER, THE LACEY OAKS AND SHIN OAKS ARE THE EXCEPTION HERE.  Inspite of being of the white oak family, they are highly suseptable to oak wilt and there is absolutely no chance of saving  these trees no matter what the degree of infection and mortality is very very rapid.   

 

Texas Red oaks (Spanish oaks) and Live oak trees are highly susceptible to a lethal fungal blight, Ceratocystis fagacearum, referred to as oak wilt. Consequently, many Texas residential aresa and ranches have lost and will continue to lose their only shade trees as well as the remaining oak trees in their pastures. For over 25 years oak wilt has wrought ecological and economical havoc on par with that of the Dutch elm disease and the pine bark beetle. Newly infected Red oaks are cut down and destroyed, fungicides are injected into the trees and bull dozers have ripped millions of feet of trenches around the surviving Live oaks to prevent the fungus from spreading from root to root. The damage is estimated in millions of dollars and hundreds of thousands of dollars are being spent for trenches and the instalation of the new bioguard barrier as a means of control that has still not proven to be effective, and yet the real problem, human management of woodlands, and possible capture and sterialization of the nitidulidae beetle, has not been addressed.

 

A Cloned Mott of Live Oak Trees

"Sometimes when you are walking through what you  think is a grove of Live oak trees, you are really simply                                                                 walking through a grove of a single individual tree."

 

William M. Ciesla,  Forest Health Management International

 

                                            

            

            
                                                                                                Photos by Jim Rediker

2. The oak wilt fungus can also be carried from tree to tree by insects. Overland transmission happens in spring and the fall, when a "fungal mat" forms under the bark of an infected tree (The Texas Red oak or Spanish oak), causing the bark to break open. While the beetle is feeding on the fruiting fungal mat, they accidentally pick up fungal spores, much the way a bee or hummingbird may accidentally pick up pollen when it sips nectar from a flower. If a beetle dusted with spores is then attracted to another tree that has a fresh wound oozing sweet sap, the spores enter the tree through the wound and the fungus starts to grow. Live oak trees do not produce spore mats, the Red oak is the only tree that produces the inoculum fungal mats.   

Another recommended step is cutting down dead trees BEFORE spring arrives, The Texas Red oak or Spanish oak. that dies in late summer or early fall should be removed immediately and burned. Otherwise in the early spring the spore mats form under the bark and break open and attract feeding beetles. After a few months of summer heat, any fungus in the tree will be killed if the tree is not destroyed during the winter. Spore mats do not develop during summer months as temperatures above 95 degrees F. will dry out and destroy any potential fungal mats.

Since oak wilt is native to North America, one question that arises is, why has this disease become so common in recent years?. The disease seems to be intensifying mostly in urbanizing areas--in places where people are buying building lots in wooded settings. As the lots are prepared for homesites when the disease is spread by the beetles, trees are inevitably nicked and damaged by bulldozers or other machinery. Homeowners can urge contractors to protect trees with fencing and otherwise work to minimize the damage to live trees. (See Oak Wilt - How It Was First Controlled)

Oak wilt fungus has been a serious problem for homeowners, because the value of your property goes down when your mature shade trees die. But ecologists say the fungus may actually be a GOOD thing for forest ecosystems. In recent years, the national policy to prevent forest fires may have allowed some stands of oak trees to become TOO dense. When trees die of oak wilt, however, GAPS open in the forest canopy--and these sunny clearings are attractive to wildlife.