According to the public radio report, RAD or Rapid Apple Decline is just what it sounds like. Apple trees just up and die for no apparent reason.
The report goes on to say that RAD hasn’t spread to West Virginia, but is currently wreaking havoc in Pennsylvania orchards. I’m not claiming to be as capable as the fruit research people who are working to correct this problem.
I’m just a former orchard hand who happens to host a weekly column. Therefore, like the lunch counter politicians and Monday morning quarterbacks of whom I’m often critical, I’m casting my 2 cents into the ring regarding this plague.
Actually, (not a-a-a-actually) there is one condition that is observed in all cases of RAD — rotting on the tree’s trunk at the site of the graft.
The graft in apple-growing has nothing to do with governmental organized crime corruption. Rather, it is where the tree’s rootstock and scion wood join together.
If the rootstock was simply allowed to grow by itself it would — likely as not — produce a wild, non-commercially viable apple. To keep a desired variety constant over acres and acres of trees, the rootstock is snipped off and a twig of the desired variety is applied. The rootstock and the twig — or scion — then fuse together much like bone when a fracture is mending.
So, let’s look at rootstocks. I’m really not sure how dwarf rootstocks are mass-produced to be so identical that we can assign them model numbers.
Dwarf trees never really piqued my interest. I’m a proponent of the old-fashioned full-size random seedling rootstock for reasons perhaps more nostalgic than practical.
Perhaps our meddling in this field has helped to bring about this problem.
Many current researchers may be too young to remember the MM106 rootstock disaster of the ’70s and ’80s. In a 1984 conversation with grower Baden Larrick, he described his experiance after planting a block of Golden Delicious trees on MM106 rootstock.
The first real crop of big, luscious apples filled the wooden 17-bushel bins so that space in the rows between the trees became inadequate to contain them.
In the subsequent few years, the trees rapidly declined and died — or nearly died before being pushed out and another variety — not on MM106 rootstocks was planted.
“Collar rot” was the culprit common to these rootstocks. I’m uncertain after all of these years whether the term refers to rot at the graft site or below it where the roots enter the ground.
Like stars and snowflakes, everything in nature is based on a principle of infinite diversity. So it goes with apples.
Grower Gordon “Tom” Whitham explained to me that if every seed of every apple ever grown were planted, each would produce a different tree and a unique apple. The difference may only be microscopic, though it is often more dramatic, but no 2 varieties will be exactly alike.
(Every apple core that gets ground up in your trash disposal represents a multiple extinction, that’s why we always toss ours outdoors. If I ever stop mowing, a fruit tree jungle would be the likely result.)
Some of us tend to look to the past for solutions to modern problems and not without good reason. As we’ve often heard of late, diversity of crops is the natural defense against widespread plant disease.
Uniformity is a sitting duck. It’s just a hunch, but I strongly sense that if we were to go back to using seedling rootstock, RAD would largely disappear.
Of course, the trees would grow very large. We would again have to allow 40 feet both ways per tree and stop trying to grow apples like a row crop. We would also have to learn to use 24-foot ladders as well.
To be honest, I have very little practical experience at fruit tree grafting. In the orchard, my job description could change in an instant if a tractor wouldn’t start or the clutch went out of a truck or labor transport bus.
Thus I was often getting pulled from the field before having had a chance to develop some of the more specialized skills of pomology.
I have absolutely no experience with propagating fruit trees through a process called “layering.” In fact, my only knowledge of the process is from the book “A Reverence for Wood” by Eric Sloane (Random House 1974).
Layering is accomplished by directing a live twig of the tree of a desired variety through soil, either underground or through an elevated container and thus encouraging it to root. Once it roots, the twig is cut free from the parent tree and replanted elsewhere.
Sloane depicts the process beautifully in pen and ink on page 85. I’m willing to testify that, in principle, the method does work. In some species such as forsythia it’s almost impossible to prevent.
The book goes on to describe a process that seems too time- and labor-consuming to have any practical commercial application. But, a tree propagated in this manner would have no graft union to rot.
Back in my orchard days, we were sent out amongst the rows of trees to mow the brush and weeds. I don’t recall if this was as an alternative to herbicide or as cleanup where the sickle-bar mower or herbicide boom couldn’t reach.
We were equipped with scythes — today, it’s gas powered string trimmers a.k.a. “weed eaters.” It is possible to girdle a tree with a string trimmer.
To girdle a tree means to sever the cambium layer that lies just below the bark and preventing the flow of sap to the tree. This can be avoided through reasonable care on the part of the worker.
However, the string could be spreading disease and actually be infusing it into the tree through invisible cuts at the trunk, exposed roots or sprouts growing up from the roots.
What kind of disease? Who knows? It’s long been said that everyone’s backyard contains undiscovered species of insect and microbial life.
As an example, I arrived at a farm near Summit Point and there found an old ewe near death, all veterinary efforts having been expended to no avail.
The owner explained that she had caught a disease from the ground that was spread through deer feces. The deer carry this germ, but are immune to its effects as are we and every other animal except sheep.
Give the weed eater to the gardener and sharpen the scythe and see if things don’t improve.
One final thought; Perhaps RAD will be traced to a batch of mis-packaged or mis-labeled herbicide or spray material.
Well, that’s my advice for what it’s worth. The 2-cent figure at the outset may prove accurate after all. But really, we need your suggestions, preferably in the letters-to-the-editor section. Maybe if we put our heads together along with the official research people we can be ready for RAD before it arrives in the Mountain State.