Question: Does the 'dna' weaken year over year when propagating from the same family of Smarged (Emerald Cedars) eg: year 1 - take cuttings from 1 gallon cedars, to propagate, after rooting, upshift from cuttings to 1 gallons. year 3 - take cuttings from those propagated -upshifted 1 gallons to use for year 3 propagation. So at the end of the day, our company's cedars are all from the same family year after year. After 8 years of getting our cuttings this way, the past 2 years, we ended up with Kabitina on some of the cuttings. Have we weakened the plant because the DNA is split, then split thinner etc? Jill
An intriguing question! One might assume that a vegetative clone of a parent plant would be genetically the same, but the answer isn't so simple. First of all, in most scenarios, it does stay the same. There isn't any sort of dilution or weakening due to cloning/cuttings/etc. multiple times. But, at least a couple things can rarely happen. 1) if there is a mutation in the body tissue of the plant (a "sport") and that is the part that is propagated, then that would find its way into the cuttings in successive plants. Some examples of famous sports are red anjou pears and the Ruby Red grapefruit... but there could very well be a sport that gets propagated that doesn't have positive properties (and not be visually apparent): https://en.wikipedia.org/wiki/Sport_(botany) 2) epigenetic variance -- in this instance, the DNA is exactly the same, but the physical trait that gets expressed (e.g., leaf colour or fewer defensive compounds) becomes inherited in successive propagations: https://en.wikipedia.org/wiki/Epigenetics Of note, Finding stable epigenetic variants is (super-recently) being considered as a way to find new crops if the mutation variant can be stabilized, such as in this 2019 paper: Epigenetic variation for agronomic improvement: an opportunity for vegetatively propagated crops All that said, the likely answer is some bad luck in having the fungus establish in your nursery.
What there is, is change in the behaviour of cuttings depending on where the cutting comes from. Cuttings taken from low down on a side branch on a mature tree will grow very slowly, and won't develop good shape - they have in effect become programmed to behave as branches, indefinitely. The best growth is from cuttings taken near the top of vigorous young trees. So replace your stock plants frequently, every few years.
I experienced that with cuttings taken from Sequoiadendron giganteum : the cuttings taken from side branches would have to be staked to stay upright, while one taken from the leader (on a small nursery tree, I don't do tree extreme climbing!) took the usual upstraight look of the mother plant.
Yes, to a greater or lesser extent; same applies to graft scions too, for species that won't root from cuttings.
