I have a 2 year old apple tree in a pot, made from a scion taken from a macintosh tree planted by my grandfather at my childhood home in 1961. My mother died 2 years ago and the house was sold. The new owners cut the tree down so there is no chance of trying again. The nursery man made 8 trees with dwarf rootstock. This is the only survivor. He thinks the original tree may have had a virus. I’ve included a picture that show the graft union and the wound at the bottom of the trunk that look to me like symptoms of a virus. The tree actually looks quite healthy otherwise and grew a lot this year. It’s about 30″ high from the soil level
Is there anything I can do to help the tree survive? Should I, or is it probable that it would be transmitted to any other apple trees nearby? I’d like to have another one as well.
It is such a lovely idea to perpetuate a tree from your childhood, and easily understandable that you would like to do whatever you can for this last survivor.
Although it is not possible to say with certainty, from your photo and description, it is possible that you are noticing the appearance of virus symptoms, most of which affecting apples are transmitted through grafting. Tomato Ring Spot virus is an exception, and it causes apple union necrosis and decline. Infected trees can spread viruses slowly to adjacent trees. It should be noted that all viruses of apple are transmitted through vegetative propagation and grafting, with the exception of the Tomato Ring Spot virus which is transmitted by nematodes which can carry this virus from tree to tree.
It is also possible that the original grafting was not done correctly, or that there is an incompatibility between the scion and the root stock (although this is generally not a problem with apples). If this is a wound at the graft site, caused by some other external factor, it may be able to repair it professionally with a process known as “bridge grafting”.
There have been recent reports of young apple trees grafted onto dwarf rootstock contracting a condition known as RAD or Rapid Apple Decline, whose causes are not known. If this is what has happened to your young tree, the advice is to try your best to minimize stress on the tree by good irrigation and protection throughout the winter against southwest injury (also known as sunscorch) which can cause cracks in a tree’s bark, often close to ground level, which can promote disease. White plastic tree guards can help here.
If your tree has great family and sentimental value, it is worth getting in touch with an arborist who should be able to confirm whether your tree has a virus, and what the recommended course of action could be.