A Better Swedish Aspen
This idea could make you millions.
This is a long term, moderately high risk (it could well not work), fairly cheap project that potentially can make millions. It will also make your name.
When we were just starting, Swedish aspen was about a quarter to half of our total sales. It's narrow form, fast growth, and easy care made it very popular on small lots for privacy screening. But Swedish Aspen suffers from bronze leaf disease. This is a fungal disease that usually kills the tree in about 4 years. All columnar swedish aspen are clones of a single mutation discovered in (surprise!) Sweden decades ago. They are genetically identical so all are susceptible. Breeding a resistant tree is not possible directly.
In some trees columnar forms are a single mutation. The resulting gene is usually recessive. In some cases (columnar apples) it's incompletely dominant. Columnar trees can result from one of several mutations:
- In most trees the leader produces an auxin that tells all the other branches, "You aren't the tip, grow out not up." In swedish aspen I think that the gene that codes for the receptor for this gene isn't working, so all branches try to go up.
- Most trees have a characteristic branch angle that a branch makes with the trunk. If the gene that controls this angle mutates, then the branch angle changes. A good example of this is columnar colorado spruce, and parkland pillar birch.
- In columnar apple, the change is more radical. The trunk is stockier, internode distance shorter, and instead of branches the tree produces fruit spurs. This is one of the most extreme columnar forms I've seen.
In Prairie Skyrise Trembling aspen side branches remain short -- only about 18 inches.
This project would take somewhere between 15 and 25 years, but requires fairly small amounts of work: Mowing, weed control, watering during establishment phases -- roughly the same amount of work as a similar area devoted to small pot production, the rest of the interval would be similar to field maintenance.
What is needed:
- Set up several groves preferably in open areas where there is no swedish aspen at present. Each one is about ΒΌ of an acre and has about 100 european aspen.
- As the trees mature and identify as male or female, destroy the males.
- Bring in a mature swedish aspen.
- Disturb the soil between and around the grove to make good conditions for seed sprouting. This has to be done without damaging existing roots, as they will sucker like crazy. Or place trays of prepared media. This is the F1 generation. If the columnar gene is dominant, you will see columnar trees. However this is unlikely, else there would be lots of them around the site where the first one was found. (It may be easier to harvest the seed, and sow in a new bed, or place filled styroblocks under the trees as the fluff comes down.)
- Once you have a well established F1 generation, remove the parents. Bring in a tree with bronze leaf disease into half the groves. After leaf drop spread its leaves around all the F1 trees. Some, possibly most, of the trees will succumb to BLD. These groves are going to be the source of BLD resistance.
- In the other half of the groves attempt to keep them BLD free. Here you are looking for columnar trees.
- In another 5 years or so, the F1 generation will mature. Again, create seed beds ready for the fluff.
- This is the F2 generation. If the columnar gene is a simple recessive, one-fourth of the trees will be columnar. If it is not simple, you may get only a very small number of columnar trees.
- Expose the grove again to BLD.
- From the columnar survivors, you now have a breeding population that you can use to breed increasingly resistant trees.
Risks:
If the columnar gene is on the same chromosome that the caries susceptibility to BLD all the columnar trees may die from BLD -- you won't get ones that are immune.
If the columnar habit is the result of a bunch of gene interactions this won't work.
Tower poplar is the result of of a columnar swedish aspen cross. It has both the columnar growth habit, and about half the susceptibility to BLD.
Don't be tempted to use the F0 males as breeding stock. Yes they carry the columnar trait, but they also are known to get BLD.
Lodgepole Pine in our front yard.
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