Growing fruit trees - Organic vs Un-treated

[FB.]

I don't know whether you have seen it, but there is an interesting account by Stephen Hayes on his fruitwise internet site of his experiences setting up a 5 acre orchard in Hampshire from scratch and deciding to abandon organic production techniques due to increasing pest and disease problems. His section on these also has some nice photos - a bit depressing really if you are an untreated/unsprayed advocate.

see: pestsanddiseases

However, from reading his orchard planting scheme I don't think he tried out your suggestions for combating pests and diseases with alternating rootstocks/disease resistance varieties in his row planting.

Apparently he chose MM106 rootstock and planted them in a fast-draining, poor-moisture-retaining sandy soil which MM106 does not cope well with (I can testify to that!).

If he had chosen MM111 or M25 the trees would have been strong enough.

I made the same mistake; planting on M26 and MM106 - misled by over-optimistic size guides in "the books".

Most of mine are now replaced with MM111's and M25's, which do have the strength to shrug-off the problems. I'll re-post the picture of a young M25 shrugging-off a severe aphid attack which would have severely weakened a MM106 or other dwarf/semi-dwarf.
Not only the picture below, but my MM111 Belle de Boskoop, a few years ago, when it was only a few years old, had its whole side ripped off by a broken branch early in the growing season (after leaf-out). It was stunning how quickly it recovered - and the wound is now almost invisible!
I'll see if I can get a picture of the healed-over wound in the next few days.
MM111's and M25's - especially with triploids grafted to them - are seriously tough.

[boundtothesoil]

As I wrote before, coddling moth is no issue. There is a virus for sale that kills every single one of them. .

This virus product (Granupom) sounds great. I've looked on the internet and it seems to be licensed by the EU for use in the UK, but after a few related googles I can't locate a supplier in the UK. Maybe it's sold under another name or by another company here.

[FB.]

.....a bit depressing really if you are an untreated/unsprayed advocate......

No need to get depressed.
Grow trees on more vigorous rootstocks. The reason "seedling" rootstocks are fairly vigorous is because that's how vigorous mother nature felt they needed to be, in order to survive before mankind came along and started keeping them and nurturing them in his garden.
Seedlings, on average, are about the same vigour as MM111 and seedlings are probably a little less vigorous than M25, although vigour varies a bit because of genetic differences between them and the way each seedling can tolerate different soils or climates.
Almost all random seedlings are more vigorous than M26. Most are less vigorous than M25.
So grow on MM111 or M25 and you'll have a tree with the kind of vigour level that mother nature imparts on the "wild" form which must survive all by itself.

The stronger roots also ensure a better supply of balanced nutrition to the canopy, which improves tree health and fruit quality when the soil and growing conditions aren't perfect.
My incidence of disease (such as mildew) or nutrient imbalance (such as bitter pit) tends to be much lower on MM111 or M25 than on MM106 or M26.
One exception seems to be that M26 seems to slightly improve scab resistance, compared to the same scion on M25, but if the scion is fairly scab resistant, it shouldn't matter if it's on M25.

.

[Marcher]

FB, do you think there are any other Malus species that could be crossed with domestica to impart resistant genes? Resistance to certain pests and diseases I mean.

With grapes the European vinifera vine is pretty disease and pest prone due to these being imported with other varieties from the Americas. It is so bad now that it isn't trusted on its own roots in continental Europe and America due to Phylloxera. But resistance can be bred into them by crossing with other varieties - cold resistance by crossing with labrusca, Phylloxera resistance with any of the American species (although some are better than others) and early ripening and late flowering with amurensis. However the taste is affected, but still some good varieties have been made from crosses.
Ultimately continuing with vinifera requires grafting onto rootstocks and spraying against pests and diseases. Either way vinifera has to be grown on a rootstock, grown on own roots in sand or grown somewhere where the disease has little presence such as Britain. To create pure vinifera resistance would require selective breeding and once achieved, crossing existing varieties with such resulting vines in order to hopefully impart resistant genes without destroying the flavour of the crossed varieties.
I think Malus domestica may go the same way if disease and pest prone varieties keep being cloned. At least, more and more varieties will fail and some in the future will become totally useless through disease and pests. With grapes, in Britain I think hybrid grape vines are slowly going to win out over more temperamental pure vinifera, at the very least in home gardens. Already varieties such as Rondo and Seyval are among the most grown here.

I'm not sure if Malus sylvestris has any particular disease or pest resistant qualities, or perhaps Malus sieversii? In any case, I think we need to go plant hunting in Kazakhstan to bring some fresh genetic material to be bred into Malus domestica from its supposed ancestor sieversii. What are your thoughts?
Apples aren't my area, grapes are more my interest but apples are good too.

[FB.]

FB, do you think there are any other Malus species that could be crossed with domestica to impart resistant genes? Resistance to certain pests and diseases I mean.

There's a great deal of resistance genes and mechanisms in the Malus domestica gene pool. It's just that many of the varieties with resistance are old and forgotten - cropping isn't as heavy as modern requirements, or the fruit is less attractive, or the trees are quirky in one way or another such as biennial or tip-bearers.

The big problem is that most people want everything in one tree. They want ultra-heavy cropping the moment it's planted, they want immunity to every pests and disease.
The problem is that such a "perfect" variety would soon become so popular that it's widely grown - and being widely grown encourages gradual evolution of cultivar-specific strains of disease.

Resistance in the wild comes from each plant being a genetic individual. Being individual makes it much more difficult for pests and diseases to specialise; the diseases have to attack lots of different varieties to a minor extent, rather than being able to adapt perfectly to attack vast orchard blocks of the same variety (e.g. a block of Gala).

Genetic diversity is key to durable resistance - it's also the "natural" way for plants to grow, rather than being grafted (a form of cloning developed by humans).
But genetic diversity within an orchard doesn't fit with mass production requirements of modern culture, where the commercial orchard wants to have all trees the same - all harvested at the same time, all fruit of the same size and colour, all stored and packed at the same time.

[sugar]

This virus product (Granupom) sounds great. I've looked on the internet and it seems to be licensed by the EU for use in the UK, but after a few related googles I can't locate a supplier in the UK. Maybe it's sold under another name or by another company here.

There are several names : Carpovirusine, Granupom, Madex, Cyd-X, all based on the same granulose virus
Distributor for Biobest in UK is Agralan Ltd, I would contact them...

FB, do you think there are any other Malus species that could be crossed with domestica to impart resistant genes? Resistance to certain pests and diseases I mean.

With grapes the European vinifera vine is pretty disease and pest prone due to these being imported with other varieties from the Americas. It is so bad now that it isn't trusted on its own roots in continental Europe and America due to Phylloxera. But resistance can be bred into them by crossing with other varieties - cold resistance by crossing with labrusca, Phylloxera resistance with any of the American species (although some are better than others) and early ripening and late flowering with amurensis. However the taste is affected, but still some good varieties have been made from crosses.
Ultimately continuing with vinifera requires grafting onto rootstocks and spraying against pests and diseases. Either way vinifera has to be grown on a rootstock, grown on own roots in sand or grown somewhere where the disease has little presence such as Britain. To create pure vinifera resistance would require selective breeding and once achieved, crossing existing varieties with such resulting vines in order to hopefully impart resistant genes without destroying the flavour of the crossed varieties.
I think Malus domestica may go the same way if disease and pest prone varieties keep being cloned. At least, more and more varieties will fail and some in the future will become totally useless through disease and pests. With grapes, in Britain I think hybrid grape vines are slowly going to win out over more temperamental pure vinifera, at the very least in home gardens. Already varieties such as Rondo and Seyval are among the most grown here.

I'm not sure if Malus sylvestris has any particular disease or pest resistant qualities, or perhaps Malus sieversii? In any case, I think we need to go plant hunting in Kazakhstan to bring some fresh genetic material to be bred into Malus domestica from its supposed ancestor sieversii. What are your thoughts?
Apples aren't my area, grapes are more my interest but apples are good too.

Some new resistant apple varieties, originating from Pillnitz (Dresden) (names starting with Re: Reanda, Rewena, Reno,...) have a scab-resistance by crossing with Malus floribunda. From what I've read, most have a very good resistence.

A lot of the other new scab-resistent apples (Topaz, Ecolette, Rajka, Rubinola, Santana, Pilot) have a resistance based upon the VFgen, and the scabvirus seems capable of tearing down this resistance by mutation, once again no experience, just read.

[sugar]

But genetic diversity within an orchard doesn't fit with mass production requirements of modern culture, where the commercial orchard wants to have all trees the same - all harvested at the same time, all fruit of the same size and colour, all stored and packed at the same time.

And sometimes, mass production of one variety is not enough. Pink Lady apples are selected on colour, size and shape. I've heard that only 1/3 of those apples are sold as Pink Lady. Check them out in the supermarket, it seems they've been produced in a factory, on a turning table and painted afterwards.

[Marcher]

There's a great deal of resistance genes and mechanisms in the Malus domestica gene pool. It's just that many of the varieties with resistance are old and forgotten - cropping isn't as heavy as modern requirements, or the fruit is less attractive, or the trees are quirky in one way or another such as biennial or tip-bearers.

The big problem is that most people want everything in one tree. They want ultra-heavy cropping the moment it's planted, they want immunity to every pests and disease.
The problem is that such a "perfect" variety would soon become so popular that it's widely grown - and being widely grown encourages gradual evolution of cultivar-specific strains of disease.

Resistance in the wild comes from each plant being a genetic individual. Being individual makes it much more difficult for pests and diseases to specialise; the diseases have to attack lots of different varieties to a minor extent, rather than being able to adapt perfectly to attack vast orchard blocks of the same variety (e.g. a block of Gala).

Genetic diversity is key to durable resistance - it's also the "natural" way for plants to grow, rather than being grafted (a form of cloning developed by humans).
But genetic diversity within an orchard doesn't fit with mass production requirements of modern culture, where the commercial orchard wants to have all trees the same - all harvested at the same time, all fruit of the same size and colour, all stored and packed at the same time.

Yes, no one wants to grow from seeds though for obvious reasons. I think the best thing to be done is to just encourage disease resistant varieties to be grown and try to break the dominance of certain varieties in supermarkets and garden centres by eating a wide range of types. I guess it's common sense, but most people will sadly still stick to their one variety - Cox's, Golden Delicious, whatever else...

[FB.]

And sometimes, mass production of one variety is not enough. Pink Lady apples are selected on colour, size and shape. I've heard that only 1/3 of those apples are sold as Pink Lady. Check them out in the supermarket, it seems they've been produced in a factory, on a turning table and painted afterwards.

Yes, Pink Lady are the most ideal apples from the orchard. The lesser grade Pink Lady are sold as Cripp's Pink.

[FB.]

A lot of the other new scab-resistent apples.........have a resistance based upon the VFgen, and the scabvirus seems capable of tearing down this resistance by mutation.......

The best resistance is where several genes work together. Polygenic resistance is the term usually used to describe it. Monogenic refers to a single gene, such as Vf.
Using a single gene only takes a single spore mutation to defeat it. Multiple genes require multiple mutations to defeat it.

Let's suppose we have a strain of scab which has been fortunate enough to defeat the Vf resistance.
Let's suppose the scab has a single gene mutation. This gene has a 50% chance of being inherited by its spore offspring. Therefore half its offspring will be capable of attacking Vf - and some of those offspring may have mix-and-matched other genes which make them even better than their parent.

Let's suppose we have a strain of scab which has managed to overcome polygenic resistance - defeating five minor resistance genes after many years of mutation.
Let's suppose those five minor genes are on different chromosomes.
What's the chance of each spore offspring managing to inherit all five? It's 3%.

So where a single-major-gene resistance is defeated, the next generation of scab spores are 50% infectious to the tree from which they came.
With five-gene polygenic minor resistance, only 3% of the next generation of scab spores are infectious to the tree from which their parent came.

Which explains why, once Vf resistance fails, it spreads very quickly. Failure of polygenic resistance is more gradual, although will vary depending on whether the polygenic resistance is based on as few as two genes, or as many as seven or even ten.
Also depending on the climate being favourable to the disease.

"In the wild" each individual tree has a unique combination of minor genes which mean that it is difficult for diseases to adapt to it (it's a genetically different tree to its companions) and if it has several minor resistance genes (which may not be the same as its companions), even fungal spores produced on its own leaves are mostly non-infectious as the spores mostly don't "get lucky" and contain all of the mutations necessary due to random distribution of those pathogenic mutations between the offspring (spores) produced by the fungus.

But resistance to pests or diseases isn't just due to resistance genes; it can be due to structural changes in leaf, bark or fruit-skin tissues.
Thick-skinned fruits or tough-fleshed fruits tend to be more resistant to pest damage. That's hardly surprising, given that a codling moth larva will have to expend more energy getting in, through and out of the fruit if the skin and flesh are tough. While the newly-hatched and very small codling maggot is expending energy trying to get in, it may run out of energy (especially if it has already crawled quite a long way), or be found and eaten by a predator.

[boundtothesoil]

Canker and scab can be kept under control by planting adjusted varieties (a local university tested hundreds of varieties over several years and selected 20 fruit varieties being almost resistent to scab and canker).

Do you have a list of these 20 resistant varieties? They might be of interest to people in the UK.
And picking up on FB's post, are they all based on possession of the single Vf gene?

[orangepippin]

It's also worth remembering the rootstock can impart disease-resistance. The "MM" series rootstocks such as MM106 and MM111 were derived from the original Malling "M" series, but developed specifically for resistance to woolly aphid.

The Geneva "G" series rootstocks were developed in the USA to confer resistance to fireblight, a significant disease of apples in parts of North America and southern Europe.

The M9 and M27 Malling-series rootstocks have some resistance to fungal infections of the root and graft union.

[boundtothesoil]

In any case, I think we need to go plant hunting in Kazakhstan to bring some fresh genetic material to be bred into Malus domestica from its supposed ancestor sieversii. .

.

I came across some information on apple collection from Kazakstan in the 2007 edition of the Midwest Apple Improvement Association Newsletter. Because this seems hard to find on the internet these days, I'll summarise one or two points.
Apparently the US Department of Agriculture made a collection of genetic material from Kazakstan in 1992. The seeds were grown up at Cornell University and screened for resistance to fire blight, scab and powdery mildew (plus other things, I imagine). Budget cuts intervened and a subset of these ended up at the Dawes Arboretum in Newark ,Ohio. After 10 years in the ground the author drew the following conclusions:-
1. The Kazak trees bloomed on average one week earlier than most commercial varieties.
2. They matured their fruit on average in late July
3. They had an average fruit size of less than 2 inches -nice crab apples!
4. They avoid spring freezing damage (of major concern to the mid-west breeders), by dropping their fruit very early, thereby minimizing the amount of photosynthates (sugars) lost in the crop, and enabling more photosynthate to build up in the tree over the next 3 months before winter, thereby lowering the freezing point of their reproductive tissues during the following winter and spring (i.e. maximizing their antifreeze levels). This strategy always ensures short season, poor quality apples (like Beauty of bath?).

The author concludes that 6000 years of selection by humans has emphasised later than average bloom dates and maturity dates, and larger than average fruit size. He doesn't mention anything about disease resistance, although other articles mention screening collections of Malus sieversii from Kazakstan, and the promise shown by Malus tschonoskii (Japanes Pillar Crabapple) which is resistant to feeding attack by Codling moth throughout the season, but unfortunately from the standpoint of eating quality is full of phenolic compounds and the plant defence-related enzyme polyphenol oxidase.

Incidently, this breeders association has used the newish variety Honeycrisp as the parent in a lot of their experimental crosses.

[orangepippin]

.
Incidently, this breeders association has used the newish variety Honeycrisp as the parent in a lot of their experimental crosses.

Honeycrisp is probably the most popular orchard apple variety in the US at the moment. It has a nicely balanced flavour that will certainly appeal to UK tastes, and early indications are that it is well-suited to the UK climate. I really like it.

We have found it slightly prone to mildew but resistant to scab, and it always produces nice clean apples. It was one of the few apples in our collection (along with Rajka, another disease-resistant one) that produced well in the dreadful 2012 season, so I think the disease-resistance that was part of its development really works.

Also, being new to the UK, and with a somewhat obscure parentage, it is unlikely that the UK bugs and diseases will be able to adapt to it soon.

[orangepippin]

I came across some information on apple collection from Kazakstan in the 2007 edition of the Midwest Apple Improvement Association Newsletter. Because this seems hard to find on the internet these days, I'll summarise one or two points.
Apparently the US Department of Agriculture made a collection of genetic material from Kazakstan in 1992. The seeds were grown up Cornell University and screened for resistance to fire blight, scab and powdery mildew (plus other things, I imagine). Budget cuts intervened and a subset of these ended up at the Dawes Arboretum in Newark ,Ohio.

I visited the USDA Malus sierversii collection at Cornell Geneva in October. The trees are extremely diverse, in size, growth habit, fruit color etc. Most of them grow as bushes, ranging in height from 3m to 6m. They do not look anything like the "traditional" orchard trees you see in old photos. I would agree that they seem to be early/mid fruiting rather than late fruiting, although there were plenty still palatable on our visit.

Although planted in regular blocks, they seem to have been left to their own devices and after walking a few yards into them you are completely cut-off from the rest of the site and just surrounded by these unusual and ancient trees. It is a strange experience.