Can diseased apricot tree be salvaged?
Q: My old apricot tree (some 10-12+ years old) has root canker, which, I have been advised, is untreatable. We have removed one large branch which did not put out leaves, but still see some of the tell-tale discoloration of disease where that branch joined the trunk. I am resigned to its demise, probably by next year. I have saved pits from this year’s pitiful (pun intended) crop, and I am planning to try to grow another apricot tree, following instructions obtained on the internet, because the fruit has been exceptionally flavorful. I have three questions regarding this plan:
1. Would the stones also carry the organism that causes the canker?
2. If I plant in a pot (so I can “baby” it through the winter indoors), would it object to being transplanted later?
3. Is the soil where the tree is located likely to be contaminated, and if not, should I transplant it there or far away from where the old tree is now?
Thank you for any advice you can give me!
Maggi, Las Cruces
A: I will first answer the question you did not ask. Will the fruit be as tasty as those from the dying tree? The answer is maybe. Because the trees are cross pollinated and the variety of the dying tree is also from mixed parentage, the fruit from each pit may be different from each other and from the parents (whoever the pollen parent is). The fruit may be equal to fruit from the parent tree, worse, or maybe better. Now that you know that, I suspect you will still want to grow new trees.
Your question about the seed carrying the disease is a good question, but the answer depends on what disease has infected the parent tree. I suspect your tree has crown gall disease which can cause galls — cankers or tumor-like growths on roots, trunk, and stems. This disease results when a bacterium infects the tree, causes a change in genetic expression in the infected portion of the tree that results in the canker. The canker can interfere with movement of water and nutrients from the roots to the top of the tree causing the symptoms you have described. To be sure, contact your local NMSU County Extension Service agent who can confirm the cause of the canker and the possibility of disease crossing into the seed. If it is indeed crown gall, the seed will probably not carry the disease.
The crown gall causing bacterium (Agrobacterium tumefaciens) may persist in the soil where the infected tree grew. The bacterium will be most persistent in the galls that remain in the soil, so planting in a new location may be wise. Once again, check with your local NMSU Extension agent to confirm the disease and likelihood that it will persist in the soil.
It is quite possible to grow new trees from the pits saved from this year’s crop. The apricot tree is a temperate zone tree which means that the seeds are dormant when the fruit matures. It is necessary to provide special conditions to overcome this dormancy. Do this by putting the intact pits in moist potting soil sealed in a resealable plastic bag in the refrigerator (not freezer) for 6 to 8 weeks. Watch for sprouting and remove and plant pits as they begin to sprout. You can put them into pots to protect them through the winter as they begin sprouting or after the pretreatment in the refrigerator has ended. As long as you use a pot large enough to allow good root growth without formation of circling roots in the pot, they should transplant well in the spring.
Send your gardening questions to Yard and Garden, Attn: Dr. Curtis Smith at cwsmith@nmsu.edu or leave a message at www.facebook.com/NMSUExtExpStnPubs. Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist, retired from New Mexico State University’s Cooperative Extension Service. NMSU and the U.S. Department of Agriculture cooperating.