Cider And Heirloom Apple Vigor: An Hypothesis

Recently, I was on the phone with a mentor and we were discussing hedgerows (my new pet project, aside from brewing all sorts of alcohol). With some of the species I mentioned, I was told that livestock would eat them down to nothing and render the hedgerow useless. After having a few tree species rejected, I frustratingly asked: “What if I planted my hedgerows with invasives like multi-flora rose, then?!”

Without any hesitation, my mentor said: “Invasives like multi-flora rose are very delicious to many animals, like my goats.  You might be suggesting invasive plants for your hedgerow because they are vigorous and seem to outcompete everything else, but try to think about vigor from another perspective. If plants with high vigor are also the most sought after by animals, don’t you think that vigor might be an evolutionary trait to survive browse?”

This is the first time I’ve heard this perspective on invasives and I’ve really enjoyed thinking about it. After some minimal research, I found out that the subject is still debated today by ecologists as the “plant vigor hypothesis.” Generally speaking, vigorous plants have higher nutrient densities than non-vigorous plants, so herbivores are more prone to eat them. However! If the very vigorous cultivars are able to put on a bunch of girth, many herbivores aren’t able to eat the whole thing because of their jaw size.

This, of course, has got me thinking about apples. Here’s why.

In many essays on this blog, I’ve talked about how I consider many cider and heirloom cultivars to be very vigorous as compared to most of the grocery store cultivars. Vigorous cultivars are harder to prune, occupy more space (so less trees per acre), have issues with vegetative vs fruit bud proportions, etc. In general, they are harder to grow.  After reading more about this “plant vigor hypothesis,” I wonder if there is a connection between vigor and nutrient density in apples cultivars?

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From an evolutionary standpoint, a correlation between vigor and nutrient density makes sense to me. Many wild crab apples in the US have much higher tannins (aka polyphenols, which =nutrition density) than cultivated varieties. This is from the many lifetimes spent co-evolving with insects and herbivores who are trying to eat them. From observing crabapples in the “wild” and planted in landscapes, it seems as if many trees have low vigor and perhaps this is because they have evolved to have an unpalatable deterrence for animals and humans alike?

In hard cider, many of the wild crabs are too much for our palates to handle and though very nutritious, they will cause a harsh and likely negative consumer experience. So what have we done? Over time, cider drinkers/makers/apple growers have selected cultivars to grow which are palatable to the consumer, but also contain enough tannins (or polyphenols, or natural defense) to give the cider some substance.  Could it be that in selecting not-so-astringent apple cultivars for eating/drinking, we’re unknowingly selecting for more tree vigor? If the apple cultivar hasn’t evolved enough to deter herbivores through astringent taste, then do genetics dictate that it must rely on vigor to survive? 

These sorts of questions make me excited and I’ll keep learning about these processes in order to try and uncover different management ideas that don’t involve regulating vigor through the use of dwarfing rootstocks, black magic hormonal potions like Apogee (which converts vegetative buds into fruiting buds), and planting in light soils. All of those management aspects, I suspect, are making the vigorous cultivars less vigorous/more fibrous/less nutrient dense.

Thoughts to be continued, but in the meantime here are a few off the top of my head:

Thought 1: Pruning extremely vigorous varieties like an herbivore in order to get faster fruit set?

Thought 2: Continuing to fruit explore to find mixes of wild x cultivated which hit high nutrient densities, palatability, and lower vigor.  (I’m writing a fruit exploring book about how to do this at the moment)

Thought 3: Making crabapples a significant part of my home breeding program.

 

 

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Some basic thoughts on apple tree vigor

I’ve learned a lot from the orchards this year surrounding vigor, and I feel like this course of study will be life-long. We get a lot of water here in southern Appalachia and while some apple varieties manage to sip this water, others gulp it and produce massive amounts of growth. You might be thinking: Growth! That’s wonderful! And it probably is if your tree is growing in a forest and needs to grow tall in order to reach the canopy and get some sun. But for an orchard, we have goals to harvest the crop and not the timber. When you are faced with a tree that has vigorous tendencies, the energy (sap) from the roots often rockets into growing new branches instead of growing new fruits.

These vigorous tendencies of many heirloom apple varieties are part of the reason why you don’t see them at the grocery store or in orchards today. Vigorous trees are expensive to prune, often more susceptible to fireblight (a bacterial disease), tend to produce less fruit, and can’t be spaced as closely together due to being bushy. Each of these varieties are totally different apples and requires different management techniques. The difference between a black limbertwig and a roxbury russet is the same as the difference between me and my best friend from high school. In the end, we both need food, water and shelter…but its how we use that food, water and shelter which ultimately dictates our health and quality of life. Like the black limbertwig, I seem to thrive in poorer environments. Natasha, my best friend who represents roxbury russet in this analogy, most certainly thrives in richer environments where there is abundance. (She’s going to kill me if she reads this).

This is the puzzle of heirlooms that I’m excited to spend my life trying to unlock. Where are these varieties happiest grown? What practical measures can I take to bring about more balance between vegetative and fruit growth?

Here are some brief thoughts (I could wax poetic about all of these bullets but I’m keeping it short in favor of readership):

Pruning: I have been a member of the EVERY WATER SPROUT MUST GO club before and now I’ve started to rethink this membership. For the vigorous trees, perhaps it’s not a bad idea to just trim these water sprouts rather than cutting them all out (water sprout= vigorous shoot of growth that is only 1 year old) so they can develop fruit buds and maybe start producing apples in another year. Fruit buds, by the way, are produced on second year growth. See diagram below (Cox is short for Cox’s Orange Pippin, a popular apple from the UK):

Site selection: You could argue the pros and cons for planting North, South, East or West until you are blue in the face. Rather than doing this in a blog, I’ll just tell you what I saw this year: South and Southwestern slopes are your poorest and driest sites due to the sun baking off water. At foggy ridge, we have a fairly steep south facing slope with rows of trees heading North-South. At the top of the hill where it is less sloped, vigor is higher than at the bottom of the orchard where the slope has steepened. This can sort-of be seen by a picture that I recently took of the trees with flushes of growth after a bunch of fall rain. The northeast corner, which is also the “flattest” land in the orchard, has tall shoots of recent growth, whereas the bottom southwest facing corner (that you can’t see) hardly has any flushed growth. Of course, these are different varieties and I’m just speculating here, but it’s a thought. fall flush with drawing

You might want to think through planting  apples on contour if you live in a wet area with heavy soils and don’t know how the varieties will respond. That is, if you are going for fruit production. In Kyrgyzstan, the wild apples were growing on depleted, dry soils. Contour will help you to harvest nutrients instead of them flowing down slope, but could also result in gigantic half-barren trees.

I won’t get into soil type, but that’s also important, if not the most important. Some apples want to be grown on sandy soils, others on clay soils. Some like wet roots while others like dry! The only way we’ll find out is if people start planting the same trees in different soil types.

Rootstock Selection: We have now have a not-so-secret weapon that all those men at the pomological society meetings didn’t have 100 years ago. Dwarfing rootstock! The size of the root ball basically dictates how much water and nutrients the tree will get. Think of it like arteries. If you have clogged arteries (dwarf rootstock), your activities are limited due to a reduced blood flow and oxygen uptake. If you have totally clear arteries (standard rootstock), you aren’t restricted by blood flow and you can go run a marathon if you want. Let it be known, dwarfing varieties die much more quickly than varieties grafted to larger rootstocks (much like blocked arteries cause heart attacks which kill at an earlier age…to stick with the analogy). So, the thought goes like this: If I graft a very vigorous variety (V^3) onto a rootstock with a tiny root system, the growth would have to be moderated because those roots can only take up so much!

Is this true? Well, partially. We’re learning, still. Thanks to the hard cider movement, people are actually grafting these V^3’s to dwarfing rootstock. Soon we shall see how varieties like harrison, a very popular cider apple (and the most vigorous variety I have EVER witnessed) grows for these people on a smattering of different soil types and rootstocks. I bet there will be a particular site somewhere in the US where Harrison can grow easily and without many inputs. It makes me excited to think about finding a true home for these varieties. To me, that’s the definition of terroir.

You see, this sort of thing used to happen all of the time! People (I assume old men) would attend pomological society meetings and discuss what is working for them and what is not. This information rarely was extended to other parts of the country due to the fact that news didn’t travel as efficiently as it does now. Nowadays, we have social media for instant dissemination of information. I just need to work on getting these people to talk, experiment, compare and contribute to documents like this for their area:

That’s where young people are really important. The average age of an orchardist is in the high 50’s, low 60’s but I seem to meet a whole of of them over the age of 70.  Many of these people (men) aren’t necessarily interested in trying new things, nor are they interested in using social media. These people will keep on doing what they’ve always done. It’s the next cohort that needs to be corralled into an arena of experimentation, information dissemination, excitement and camaraderie.

That’s part of why I’m here, I guess.