Opal or Victoria Plum?

[FB.]

Makes sense, but I wouldn't downplay the trees own biology in resistance to disease. Slight changes such as a difference in bark or pores could allow in disease more easily than on another variety.

Absolutely.
There are various ways a tree can resist diseases.

1.
Antifungal chemical produced by the tree.

2.
Unusually thick/tough bark, skin or leaf surface.

3.
High vigour to simply outgrow the problem.


However, whatever the mechanism of "resistance" to a pest or disease, the diseases will be producing their own unique genetic combinations each year in the hope that one or two of those fungal spores produced will be better than its parents at attacking a nearby tree.

When I used to work in a microbiology lab, I actually saw hospital-specific strains of bacteria which were incapable of growing without antibiotic treatment; these bugs had, perversely, become "addicted" to antibiotics (the very drugs we would use to try to kill them!). We could only get them to grow by feeding them the very antibiotics that doctors would have tried to use to treat the infection in the first place.

[FB.]

Ultimately though we won't get increased disease resistance unless we allow tree to reproduce sexually instead of cloning old varieties constantly.
Some old varieties will become so poor at disease resistance that they'll have to be abandoned.

Yes, growing the same old varieties encourages build-up of disease, and is why many of the "old favourites" are rather prone to canker, scab or mildew nowadays.
A century ago Bramley was resistant to everything, but it has been so much grown that the diseases have had a long time to gradually evolve cunning ways past its resistance. Nowadays Bramley is only average disease resistance at best, although variable in different parts of the UK.

A real problem is that although in general triploids are very disease resistant, vigorous and don't need such fertile soil, they don't produce much good pollen to pollinate other trees and they don't produce many good seeds.
So most of them are not easy to breed from and we're back to breeding from diploids.

However, a lot of the "heritage" varieties are turning out to be triploid. No doubt they've managed to survive through the centuries because of the extra resilience of such trees.
Some "shockers" about a year ago (not that it surprised me) were that the following apples (and many others) were found to be "unexpectedly" triploid using modern genetic analysis techniques:
Ashmead's Kernel
Adam's Pearmain
Norfolk Beefing
Coeur de Boeuf
Hambledon Deux Ans
Tom Putt
Braddick Nonpareil
Catshead
Orleans Reinette
Tower of Glamis


So many "new" triploids. Yet apparently only about one in a thousand apple pips is triploid.
So of the few thousand apple varieties known today, we should only have a handful of triploids among them. However, we have dozens of triploids - statistically highly significant that mankind either prefers them, or (more likely) that they are tougher trees.

Consider this:
A triploid, with very few (if any) seeds per fruit, doesn't have to spend much effort "feeding" those pips. Therefore less demands put on the roots and more nutrients available to grow. Also the soil around the tree would not become depleted of essential nutrients as quickly (since fruit is mostly water whereas pips are solid matter including fats and proteins).
Then add the extra set of chromosomes from which it has more options to find some mechanism to resist whatever attacks it.
It all adds up to quite an advantage and probably explains the over-representation of triploids.

On the other hand, highly fertile and prolific pollen and seed producers such as Golden Delicious, Spartan and Beauty of Bath are considered to be "potash-demanding" presumably because all that good pollen and all those viable seeds in the fruits take a lot of feeding, with the soil easily becoming depleted - and the cropping or even the health of the tree beginning to decline as a result.

[Marcher]

2.
Unusually thick/tough bark, skin or leaf surface.

I have considered this myself (as mentioned above with regards to pores and bark). Consider citrus - tropical climates, humid, wet conditions - perfect breeding ground for disease. And what do tropical plants such as citrus usually have? Glossy, tough leaves (I'm not good at describing it, but you know what I mean).
Some varieties of Prunus such as the species Prunus laurocerasus are much less prone to disease than other species in the same genus. Prunus laurocerasus isn't bomb proof of course, but I do believe its leaves confer a good degree of protection to it. It can get mildew like many things, but I'am yet to see it on them around here - I see them on oaks everywhere, even next to it.

So ultimately if I saw an apple tree with glossy leaves growing wild anywhere I'd take cuttings and apples from it immediately and attempt a breeding programme.We need that Russian apple tree with the large taproot in breeding programmes too, I forget what it was called.


Citrus leaves


A type of cherry laurel. They vary a lot, some with more glossy leaves than others. I believe it's ultimately an adaptation to hot climates, but it may help in keeping disease out in wet and humid ones.

3.
High vigour to simply outgrow the problem.

Earth's increasing CO2 levels may gradually make a great deal of plants more vigorous anyway. Most use C3 photosynthesis which evolved during periods of higher CO2 than we have now. Of course any climate change will also have consequences though (both good and bad). C3 photosynthesisers are inferior to C4 ones under current conditions but close the gap when CO2 is increased. C4 photosynthesisers don't function well in cool climates though and are usually tropical plants.
Anyway, increased levels of CO2 on C3 plants have been shown to increase vigour and hardiness and decrease water intake. A increase in CO2 since the industrial revolution may have helped crop production increase, not necessarily just breeding and green revolutions alone.

When I used to work in a microbiology lab, I actually saw hospital-specific strains of bacteria which were incapable of growing without antibiotic treatment; these bugs had, perversely, become "addicted" to antibiotics (the very drugs we would use to try to kill them!). We could only get them to grow by feeding them the very antibiotics that doctors would have tried to use to treat the infection in the first place.

That's amazing

[FB.]

We need that Russian apple tree with the large taproot in breeding programmes too, I forget what it was called.

Antonovka.

I've tried - and failed - to source one for seedling rootstock production.


But I am working on something even better - I've been investigating what makes a good seed parent for "seedling" rootstock production.

Unfortunately the bad year of 2012 has set me back considerably - years - due to slugs eating the rootstock shoots and due lack of sunlight devigorating and the combination of factors eventually killing my M and MM rootstock stoolbeds.

[Marcher]

Yes, growing the same old varieties encourages build-up of disease, and is why many of the "old favourites" are rather prone to canker, scab or mildew nowadays.
A century ago Bramley was resistant to everything, but it has been so much grown that the diseases have had a long time to gradually evolve cunning ways past its resistance. Nowadays Bramley is only average disease resistance at best, although variable in different parts of the UK.

A real problem is that although in general triploids are very disease resistant, vigorous and don't need such fertile soil, they don't produce much good pollen to pollinate other trees and they don't produce many good seeds.
So most of them are not easy to breed from and we're back to breeding from diploids.

However, a lot of the "heritage" varieties are turning out to be triploid. No doubt they've managed to survive through the centuries because of the extra resilience of such trees.
Some "shockers" about a year ago (not that it surprised me) were that the following apples (and many others) were found to be "unexpectedly" triploid using modern genetic analysis techniques:
Ashmead's Kernel
Adam's Pearmain
Norfolk Beefing
Coeur de Boeuf
Hambledon Deux Ans
Tom Putt
Braddick Nonpareil
Catshead
Orleans Reinette
Tower of Glamis


So many "new" triploids. Yet apparently only about one in a thousand apple pips is triploid.
So of the few thousand apple varieties known today, we should only have a handful of triploids among them. However, we have dozens of triploids - statistically highly significant that mankind either prefers them, or (more likely) that they are tougher trees.

Consider this:
A triploid, with very few (if any) seeds per fruit, doesn't have to spend much effort "feeding" those pips. Therefore less demands put on the roots and more nutrients available to grow. Also the soil around the tree would not become depleted of essential nutrients as quickly (since fruit is mostly water whereas pips are solid matter including fats and proteins).
Then add the extra set of chromosomes from which it has more options to find some mechanism to resist whatever attacks it.
It all adds up to quite an advantage and probably explains the over-representation of triploids.

On the other hand, highly fertile and prolific pollen and seed producers such as Golden Delicious, Spartan and Beauty of Bath are considered to be "potash-demanding" presumably because all that good pollen and all those viable seeds in the fruits take a lot of feeding, with the soil easily becoming depleted - and the cropping or even the health of the tree beginning to decline as a result.

You make a very good argument for triploids. I hadn't actually considered the benefits myself when I planted my apple tree, I just considered them being a pain in the arse to fertilise and though I wouldn't risk it. There are other apple trees around but I don't know what they are, one is a crab apple though.
I bought an Elstar instead after hearing that Cox's was "temperamental" because a good Elstar tastes a bit like Cox's. The first year I planted it (last year) it was attacked by disease and didn't do so well. I found that it had poor disease resistance I wish I'd looked more into it now and got something like Katja instead.
Maybe if I end up replacing it I may consider a triploid. I'll try and find out what these ones around me are first. Two next door (one I saved after the top was ring barked somehow) and two at the other neighbours (appear to be on own roots, one looks like a crab apple of some sort).

[FB.]

,

When I used to work in a microbiology lab, I actually saw hospital-specific strains of bacteria which were incapable of growing without antibiotic treatment; these bugs had, perversely, become "addicted" to antibiotics (the very drugs we would use to try to kill them!). We could only get them to grow by feeding them the very antibiotics that doctors would have tried to use to treat the infection in the first place

That's amazing

Fortunately they were rare and generally only likely to be able to successfully attack patients already weakened from other serious illnesses - particularly people with severely weakened immune systems who had been on long-term antibiotics to support their weak immune system.

[FB.]

hearing that Cox's was "temperamental"

I happened to be reading a very old book about a week ago, and, incredibly, it suggested that Cox's was at its best in shallow, dry, infertile, sandy-gravelly-alkaline-chalky free-draining soil in a warm dry climate. In fertile soils and damp soils it was expected to be very disease-prone.
The author actually considered that Cox was the best "survivor" in such hostile dry/infertile soils.

I've actually been tempted by the old grower's advice to try Cox on MM111, since both scion and rootstock appear to be well-adapted to give the perfect Cox fruit in the one soil where Cox can thrive. Unfortunately, most other rootstocks will not tolerate infertile, alkaline and dry soil. The common MM106 is a lost cause in dry alkaline soil.

[Marcher]

Antonovka.

I've tried - and failed - to source one for seedling rootstock production.


But I am working on something even better - I've been investigating what makes a good seed parent for "seedling" rootstock production.

Unfortunately the bad year of 2012 has set me back considerably - years - due to slugs eating the rootstock shoots and due lack of sunlight devigorating and the combination of factors eventually killing my M and MM rootstock stoolbeds.

What? Won't the Russians export it? What are you aiming for in your rootstock breeding programme? Ireland could do with one for wet conditions - preferably something akin to Alder. (common gardening problem there is standing water and poor drainage).
I want to breed late flowering, early ripening peaches for cool climates like the UK and Pacific NW. I think I'm asking the world because they'll have a shorter time to ripen and be in a cooler climate with less sunlight. Smaller fruit in theory may offset these problems - I hope to get some stones from existing hardy varieties, grow many and select from the seedlings, in many years maybe cross some and carry on selecting (for taste as well obviously).
I've a few seedlings from a variety grown in Spain at the moment, sort of a shot in the dark. I figure that there may be a chance of a variety which may at least do fine in a greenhouse, then again they could all be rubbish. All part of the fun.

[Marcher]

I happened to be reading a very old book about a week ago, and, incredibly, it suggested that Cox's was at its best in shallow, dry, infertile, sandy-gravelly-alkaline-chalky free-draining soil in a warm dry climate. In fertile soils and damp soils it was expected to be very disease-prone.
The author actually considered that Cox was the best "survivor" in such hostile dry/infertile soils.

Hmmm. Well it did come from the South East, so maybe that's why. Most commercial ones seem to be grown in Kent anyway, it might just be trees outside of the SE that are a problem.
From that description though it almost sounds like you;re describing figs. I think some fruit species set fruit in such conditions as a survival mechanism - set fruit when tree is stressed to reproduce quickly before the plant dies. Obviously the plant can go on for years, even centuries as in the case of olives. But I do believe it to be an adaptation, I'm not sure if some apples have adapted it. Figs and olives definitely.
It would give such species an advantage in the long term in an otherwise hostile environment.

I've actually been tempted by the old grower's advice to try Cox on MM111, since both scion and rootstock appear to be well-adapted to give the perfect Cox fruit in the one soil where Cox can thrive. Unfortunately, most other rootstocks will not tolerate infertile, alkaline and dry soil. The common MM106 is a lost cause in dry alkaline soil.

I thought everything was. Can't you dig a great big hole and change the soil? It may help for a few years. What's Cambridgeshire soil like anyway, I imagined rich loams and clays from the Fens?

[FB.]

What? Won't the Russians export it? What are you aiming for in your rootstock breeding programme? Ireland could do with one for wet conditions.

My ideal rootstock would have as many of the following as possible:

1.
Raised from seed to ensure genetic individuality and making it mych more difficult for diseases to adapt to an orchard (if you plant an orchard on the same rootstock, once one rootstock gets a disease the others - being clones - may soon succumb to the same problem).
I also believe that the lack of burrknots on seedlings makes them less prone to root diseases which I have witnessed attacking the split bark in the vicinity of burrknots.

2.
Acceptable consistency in size of each tree, and reasonable consistency of quality and quantity of cropping from each batch of seedlings.

3.
Resistance to woolly aphids - even if it has to be derived from the Northern Spy and MM series of rootstocks as the pollen parent.

4.
High-level resistance to mildew in particular, since I lose the majority of seedlings to this disease within a couple of years.

5.
Medium to high vigour, to ensure the roots can meet the nutrional needs of the tree and prevent the malnutrition and sickliness which can be a problem in dwarf rootstocks.

6.
Tolerance of drought.

I have two very promising ones which meet all of the above, except that they would be "clones" taken as grafts, cuttings, root suckers etc.
One of the two appears to have vigour so high that it would vastly exceed anything currently in cultivation - probably 50% more vigorous than MM111, presumed triploid or aneuploid and just as tolerant of drought and poor soil as MM111. It might be so strong that it'd shrug off waterlogging or crown/root rots.
The other is about MM111 vigour, presumed diploid, and capable of being produced from cuttings.

I could adjust their vigour by inserting an interstock. Perhaps Gascoyne's Scarlet for super-large trees and perhaps D'Arcy Spice for super-dwarf trees.

[FB.]

What's Cambridgeshire soil like anyway, I imagined rich loams and clays from the Fens?

Soil is very variable around East Anglia. The only common link is a relatively low-rainfall climate with mild temperatures and one of the sunniest parts of the UK in the autumn, so excellent for ripening the likes of Sturmer Pippin, D'Arcy Spice and Norfolk Beefing which all usually ripen early-mid November.

Cambridge and Norwich sit on chalk hills, with sandy-gravelly soils surrounding them on the lower parts of the chalk.
The fens have quite a lot of silt and clay soil overlying the sand-gravel which itself overlies the chalk subsoil.

My soil is basically the transition from chalk hill to fen - on the gravelly "coastline" of the former fens. I have about 1ft sandy-gravelly-chalky loam, sitting on about six inches of sand, which sits on several feet or so of gravel with occasional lumps of chalk and clay.
Deep down is pure chalk.

I've added a sketch below.

[Marcher]

I have two very promising ones which meet all of the above, except that they would be "clones" taken as grafts, cuttings, root suckers etc.
One of the two appears to have vigour so high that it would vastly exceed anything currently in cultivation - probably 50% more vigorous than MM111, presumed triploid or aneuploid and just as tolerant of drought and poor soil as MM111. It might be so strong that it'd shrug off waterlogging or crown/root rots.
The other is about MM111 vigour, presumed diploid, and capable of being produced from cuttings.

I could adjust their vigour by inserting an interstock. Perhaps Gascoyne's Scarlet for super-large trees and perhaps D'Arcy Spice for super-dwarf trees.

Sounds very promising. I'm not fond of interstocks myself though - one weak point at the graft is necessary, but two make me nervous. My Elstar seems to have one though if I remember right.

Soil is very variable around East Anglia. The only common link is a relatively low-rainfall climate with mild temperatures and one of the sunniest parts of the UK in the autumn, so excellent for ripening the likes of Sturmer Pippin, D'Arcy Spice and Norfolk Beefing which all usually ripen early-mid November.

Cambridge and Norwich sit on chalk hills, with sandy-gravelly soils surrounding them on the lower parts of the chalk.
The fens have quite a lot of silt and clay soil overlying the sand-gravel which itself overlies the chalk subsoil.

My soil is basically the transition from chalk hill to fen - on the gravelly "coastline" of the former fens. I have about 1ft sandy-gravelly-chalky loam, sitting on about six inches of sand, which sits on several feet or so of gravel with occasional lumps of chalk and clay.
Deep down is pure chalk.

I've added a sketch below.

I see. My soil is variable. We're on a old sand hill (like much of Cheshire). Loam throughout most of the garden, but at the bottom it gets more like clay and at the top more like sand. I've hit rock at the bottom about 5ft below the surface, the clay makes it a rich soil though and drainage in most of it is good enough. The garden is sloping and the sand at the top is a pain as it creates dry shade under some trees.

[FB.]

We're on a old sand hill (like much of Cheshire). Loam throughout most of the garden, but at the bottom it gets more like clay and at the top more like sand. I've hit rock at the bottom about 5ft below the surface, the clay makes it a rich soil though and drainage in most of it is good enough. The garden is sloping and the sand at the top is a pain as it creates dry shade under some trees.

I'll re-post the link to the excellent Met Office UK climate maps.

Met Office: UK mapped climate averages

.

[yummersetter]

I think we should meet somewhere around Milton Keynes with a trailer load of soil and do a swap. I'd happily exchange a few tonnes of clayey gloop for something sandy, free draining with a bit of lime.

[FB.]

I think we should meet somewhere around Milton Keynes with a trailer load of soil and do a swap. I'd happily exchange a few tonnes of clayey gloop for something sandy, free draining with a bit of lime.

After the amount of rain we've had this year, I'm glad that I have a free-draining soil. I think I'd be looking at a lot of drowned trees and crown rot infection. Actually I think between now and 2015 the effects of all this rain will be seen in a lot of old fruit trees dying from crown rot.

Once I ignored "advice" from the armchair growers who write the books (using my own observations and experiments), my fruit growing experience improved considerably.
My soil is difficult, but with generous use of composts and manures in the past it has improved somewhat. Also the switch to very vigorous rootstocks has made all the difference.
So I'm actually quite happy about my soil and climate, now that I have varieties and rootstocks which are up to the task.
The best fruit is grown on relatively infertile and relatively dry soil as the tree doesn't have the energy for vegetative growth which steals nutrients from the fruits.
The problem is that modern ideas are that we should use fertile soil, irrigation and dwarf rootstocks. But that is just the opposite of what's needed for good cropping - and is why commercial growers need so many sprays, ranging from fungicides, insecticides but also to nutritional supplements because even in good soil the dwarf roots don't always manage to absorb enough essential nutrients to allow the fruit to develop properly.