Sunday, August 23, 2020

Designing a 200 year apple tree

The Endicott Pear tree. I hope I look this good when I am 400 years old.
 

In recent news, a 194 year-old apple tree in western Washington State recently died.

It was widely regarded as the oldest, single apple tree in the United States.

The oldest documented fruit tree in the United States is usually considered to be the Endicott Pear.

Identifying the oldest fruit tree is a task fraught with peril. Fruit trees are edge species and like many species that live on the edge of the forest, they often have the ability to throw root-suckers and form thickets. Another trait is that some apple trees have weak roots, the stems lay over and the branches strike roots where they touch the ground. That is, they "walk". Both of these traits are useful for edge species as taller forest species over-top them and shade them. The edge can "walk" into the earlier successional stages.

Is the "oldest" tree the oldest single stem or is it measured from when the seed first germinated?

The oldest fruit "tree" might be a low-bush blueberry clone growing on a mountain in New Hampshire.

Designing a 200 year apple tree

One factor that mitigates against a two-century apple tree is that edge species' niche involves rapid reproduction. Since taller tree species over-top and shade edge species, there are negative incentives for any traits that compete with the ability to produce vast numbers of seeds wrapped in just enough fruit to temp birds and other animals.

Consider rabbits and 'possums. Their niche is to reproduce with fabled abandoned and neither species is noted for longevity.

Long-lived tree species have a few common traits.

One trait is rot-resistant wood and bark.

Another trait is general disease resistance.

A third trait is that they are vigorous enough to put on sufficient yearly growth that internal rot cannot catch up with the outside growth of the trunk. In terms of fruit trees, that means that selections that produce large amounts of fruit will not direct enough resources to growing trunk to stay ahead of the hollowing effect of rot (which ultimately cannot be avoided).

Summing it up:

A 200 year apple tree would have good, general disease resistance especially to those diseases, like fireblight, that tend to be fatal.

They would not be excessively productive.

They would be vigorous.

Some root-suckers are desirable.

Some ability to throw adventitious roots is desirable.

Producing some fruit that is edible is desirable because the tree must survive ten generations of humans and some of them might see the tree as more valuable in the firewood pile than as a food producer if it doesn't produce some human-quality fruit.

They would probably have some ancestors from hot, sub-tropical regions where wood and bark rots are endemic. 

Some potential crosses with two-century potential:

On the female or pistillate side:

Golden (Yellow) Delicious. Most domesticated apple trees show little resistance to canker and wood roots. These four show more than most other, tested cultivars.

Greasy Pippin. Very susceptible to Fireblight. Link

Maypole (more of a large crabapple than a true, edible apple) Link

Liberty

On the male or pollen side (grafted into seed trees):

Geneva rootstocks 890, 210. These are the two most vigorous, Geneva apple rootstocks that have been highly selected for resistance to collar rot and replant complex.

Malus baccata, M. sieboldii or M. hallania from sub-tropical areas (Example)

Crabapple Barbara Ann or Dorothea

The smart money would be to produce several thousand seeds and then try to kill them by submerging them for two weeks shortly after the seeds germinated. Newly germinated seeds are very vulnerable to assorted bacterial and fungal rots and there appears to be some non-specific resistances to rot. Seedlings that resist death-by-drowning as babies show higher resistance to a multitude of wood-and-bark rots later in life. Pro-tip: don't use sterile potting media, use dirt scraped from beneath wild apple trees growing in areas prone to flooding.

Plant the trees on 6' by 6' centers and cull mercilessly based on leaf health, vigor and fruit quality.

2 comments:

  1. This is definitely going into a folder for further study. Wish I was young enough to follow through on a local study .--ken

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  2. Stuff like this is fascinating to me and it’s one of the many reasons I enjoy this blog

    ReplyDelete