New apple tree - advice please!!

[FB.]

Keeper's advised that the Phytophthora was primarily a threat to this rootstock if the soil was already infected with the disease.

Or the trees pick it up in the soil at the nursery, where trees have been grown for many years - and the trees carry it with them.
My soil had not grown fruit trees in living memory (if ever), yet I have lost a lot of trees to phytophthora despite my soil being sandy-gravelly and not waterlogged.

The tree losses in subsequent years after planting were very much batch-specific and nursery-specific, which strongly points to the trees being colonised but not showing symptoms when shipped from the nursery.
In one case, eight out of a batch of eleven trees (all from the same nursery in the same season) were dead after two growing seasons. Only one remains alive today.

Phytopthora spores can survive dormant for many years.
A combination of infested soil (most nurseries and old orchards), a susceptible rootstock (MM106) and the right conditions (saturated soil), for long enough (two or three days) is required for infection to occur. But once infected, susceptible varieties cannot be cured.

They have an initial phase, lasting a few years, where growth is slow and new shoots are weak. Sometimes leaves are a bit small and a bit sparse, perhaps with a slight extra hint of purple in autumn.
Sometimes the fruits are smaller and more colourful. Trees often have profuse blossoming.
Unseen below ground, the phytophthora "cankers" gradually enlarge and multiply. After a few years the cankers kill the below-ground portion of the trunk and the tree dies.
The problem with phytophthora is that it is much like HIV/AIDS - it often has a virtually symptomless period of a few years, before the disease really shows itself.

[FB.]

FB, if you're trees become infected with canker, why do you let nature take its course, won't that ultimately mean all your stock becoming infected?

Genetic diversity is helpful to avoid diseases. By doubling the number of varieties growing together, the disease resistance is roughly quadrupled due to specially-adapted strains of disease being unable to develop. In such mixed orchards, a disease must be a "jack of all trades" rather than a "master of one".
Many of the varieties I grow are fairly resistant, largely because they are fairly rare and the "master of one" strains which might threaten them simply do not exist, unlike in the case of the common varieties.
Also many of the varieties I grow are vigorous (both scion and roots). In many cases, if they can't resist it, they just outgrow what's attacking them. My Blenheim Orange gets canker, but its high vigour allows it to grow-over the wounds faster than the canker can grow. M25 rootstock can also recover from mild to moderate crown rot for the same reason, even though M25 has no resistance.

The more vigorous the rootstock, the better the supply of nutrients to the scion grafted to it, and the better the scion's health, so the better the scion's ability to resist disease or recover after infection.
Vigour leads to health and long life. Hence the Bramley tree is still growing in a garden in Nottingham after two hundred years.

Are the spores spread on the wind, and if so would it be worth erecting a simple screen around a young tree while it establishes itself?

To protect a young tree from canker would require an airtight screen. Even the slightest gaps would allow air (and airborne spores) to enter.
Many people fail to realise that, like crown rot, trees can carry canker with them from the nursery.
Sometimes spores have been blown/splashed onto the tree at the nursery, from susceptible nearby varieties. It is also possible that - like phytophthora - the tree has become infected but is "incubating" the disease which will break out at a later time - sometimes a young tree can carry canker but not develop it for a few years.

[FB.]

Is the 20 year old tree supposed to look like that? I much prefer the form of the 7 year old tree. I appreciate it not fully grown, but I’d want mine to maintain that more formal shape long term. Do you think that is a realistic expectation, given the nature of Kidd’s OR, and my stated preferences on tree height (4m) and form (half standard)?


Unless the trees need to be of roughly equal size to pollinate each other..?
....I’ve chosen Red Falstaff to fill this role....

A tree can look however you want it to, if you train it properly in the early years and then do a little tidying-up each winter when it's mature.

Trees do not need to be of equal size; they just need to be genetically compatible.
Kidd's OR and Falstaff are only partially compatible due to the Golden Delicious ancestry in both varieties.
It may be that a small Falstaff won't provide enough compatible pollen because the KOR will reject the pollen carrying genes from Golden Delicious which are also present in the KOR (it's a natural mechanism to reduce inbreeding).

I'd suggest that the smaller "pollinator" tree will need to be close to the big one, otherwise the bees may not bother flying to it because the big tree is more attractive.

[yummersetter]

Just to add a bit of reassurance, Phil, I've planted about 25 replacement trees in an existing old orchard and 135 mm106s in what was a grubbed out old orchard and, (touching wood of course), that Tun apple was the only one I've lost to disease so far - the others that are no longer with us either died of extreme old age, were badly dug up before transplanting, leaned till they toppled or exasperated me. And the land is on a slight slope, S/SE facing, about 15ft above sea level with a stream down two sides which floods most winters.

[FB.]

The only time I've had a real disaster with canker was when it took hold in the trunk of a young standard Tun apple, a foot up from the graft. I scrapped that tree.

Trunk cankers usually are brought from the nursery; a result of infection during the autumn of the tree's maiden year. Sometimes the scion wood carried it from an old, cankered "mother" tree.

A canker generally begins when a canker spore lands on a wound. This is usually the scar where a leaf or fruit has fallen off in autumn. The damp but relatively mild weather prevalent in autumn, and the many leaf scars are ideal for canker to make its move.

Occasionally canker will infect a mechanical injury/wound or sites of woolly aphid infection (and may be transmitted throughout and between trees by woolly aphids), but since wounds are less common than leaf or fruit scars, and wounds don't always happen in damp mild weather when canker spores are released, it is the less common route of infection.

[FB.]

Just to add a bit of reassurance.....135 mm106s........ only one I've lost to disease so far

There are probably several things going on here.

1. Your conditions are favourable, which makes the trees healthier and therefore less prone to infection.

2. The trees may be showing "survivorship bias" in that you dug up only the trees which were alive.

3. The trees were several years old when moved - crown rot is most likely to manifest itself between ages 2-5.

4. The nursery producing the trees had been careful to minimise conditions favourable to phytophthora.

5. The nursery producing the trees was perhaps not infected by strains of phytophthora capable of killing MM106. In its original Malling evaluation trials (several decades ago) MM106 was resistant to phytophthora strains of the time; it now being prone is more than likely a result of disease adaptation to common varieties, which I've spoken of many times.

[FB.]

Some nurseries have a problem with phytophthora.

If I was looking for a MM106 tree, I'd buy from Keepers or Blackmoor.

If I was looking for a M25, I'd buy from Keepers.

If I was looking for a MM111, I'd buy from Keepers.

M26, M9 and M27 are fairly resistant to phytophthora crown rots, so can be bought with a good level of confidence from most nurseries.

[FB.]

Regarding vigour and an ability to outgrow problems.....

Here's a picture of a young M25 tree outgrowing a severe aphid attack which ruined much of the early-season growth.
Notice the crinkled and curled, darker, older leaves - and a few brown/dead leaves. Such damage would have crippled a dwarf or semi-dwarf.
Then notice the burst of paler-green new shoots being produced in response to the attack (M25 trees, when attacked by aphids, tend to produce lots of extra shoots which is helpful for creating branching!).

Hence the generally longer and healthier life of more vigorous trees (Bramley being a good example); when the going gets tough, the tough get going.

M25 also seems to improve resistance to bitter pit and other nutritionally-related fruit-breakdown disorders. No doubt because the roots are very capable of finding all that the tree requires, sapflow is plentiful and the tree and its fruit well-nourished.
On the other hand, dwarf rootstocks can exaggerate bitter pit unless soil and growing conditions are good.

.............

[yummersetter]

The damaged trunk had become infected where a side branch had been removed to make the tree a standard so infection could have travelled on dirty secateurs. Sometimes what looks like canker on my trees is the start of mistletoe germinating. I have one of those at present halfway up a Claygate Pearmain trunk, which is annoying.
Just to put perspective on my previous post, I started the orchard replanting in 1990, when we inherited - first thing we did, before unpacking, was plant new trees!

[Philthy]

Decision made

Okay so I've made my choices, which are as follow:

Kidd's Orange Red, Half-Standard on MM106, 2 year old specimen.
- Ordered from Keeper's Nursery, for delivery mid March (hopefully the ground will
have dried out a bit by then).

Blackmoor Nurseries supply the superior MM111, but I think my soil PH is wrong for this rootstock. I tested the PH the other day, and it was roughly 6.2, ideal otherwise.

I'll prepare the planting site when the tree arrives. I'm planting into a lawn, which is on flinty clay, and has had roughly 35 years of steady compaction, so I'll lift the turf and double-dig a bigger area than I was going to. I reckon a 3.5m dia circle should be about right. I'll also add plenty of well rotted manure and gravel, around the tree, as opposed to under it, so it doesn't later on sink in the planting hole. This'll no doubt be a lot of work but well worth it in the long term. I'll also plant the tree on a mound.

From whats been said already the canker risk seems to vary with location and conditions, and its reassuring to know KOR can be grown in arguably wetter Somerset without too much of a problem. So considering KOR ticks all the boxes for what I am looking for in an ornamental tree, with great eating potential, I think its well worth go!

Katy (chosen over Red Falstaff), will be the pollination partner. M27, 1 year Maiden.
- To be ordered from Blackmoor (only because Keeper's are sold out).

I've chosen this variety as I'm less bothered about its fruiting attributes (which appear distinctly average), and more interested in its qualities as a tree. The overview states it is one of the easiest varieties to grow, will perform regardless of the summer weather, has long lasting blossom (so good pollinator), is resistant to canker, and does well on a dwarf rootstock. This specimen will be containerised.

If for some reason KOR doesn't work out, in the short term at least, my backup tree to try will be the Court Pendu Plat, from FB's recommendation. Ashmead's Kernel would also be a possibility, but on a small scale, which perhaps wouldn't work, but no matter as they're only possibilities for now. I like the heritage aspect of these trees.

A few additional questions:

I've noticed lime is often recommended to aid drainage in heavy soil - how does this work? I guess it would only help in soils which are too acid to start with, as the PH would be altered in the process, correct?

Will a newly planted tree be likely to develop fruits (of any size) during its first couple of seasons, and if so should they be removed?

Is it a good idea to dig the actual planting hole a bit deeper than would normally be required, and put some course gravel or rubble in the bottom, again to create better drainage?

When it comes to pruning, what is the current opinion on the use of wound paints like Arbrex?

Apologies for another long post. But thanks a lot for all the great feedback!

[orangepippin]

Arbrex - I don't use it on young trees, it doesn't seem necessary.

Katy M27 - depending on whether it was budded or grafted in the nursery, could start fruiting this summer. It would be best to wait until summer 2014. Katy is a lovely variety.

[FB.]

.



my backup tree to try will be the Court Pendu Plat, from FB's recommendation. Ashmead's Kernel would also be a possibility, but on a small scale, which perhaps wouldn't work, but no matter as they're only possibilities for now. I like the heritage aspect of these trees.

If you decide to grow Court Pendu Plat, choose a rootstock one size larger than you'd use for most varieties, since Court Pendu Plat is a slow-growing tree. So a Court Pendu Plat on MM106 would be equivalent in size to an average variety on M26, or a Bramley on M9. These are only guidelines since certain rootstocks will be larger or smaller than expected in certain soils.

Ashmead's Kernel (and other bitter-pit-prone varieties) perform best in neutral to slightly alkaline soils. Even better when grown on strong rootstocks such as MM111 or M25 as the rootstocks are strong enough to find all the nutrients the fruit needs to prevent bitter pit (which is calcium-deficiency disorder). Obviously neutral and slightly alkaline soil have adequate calcium. Acid soil may have inadequate calcium and may benefit from lime/potash/wood ash.

Annie Elizabeth is a variety which does particularly well on clay. As does Grenadier - there is some evidence that Grenadier gives the rootstock an extra bit of resistance against soil-borne canker-like diseases such as canker and crown rot. Very-late-flowering varieties also seem to give a slight boost to the crown rot resistance, probably because the tree remains "hardened-off" and dormant for longer, which gives the saturated soil longer to dry before the tree comes to life in spring.

[FB.]

A few additional questions:

I've noticed lime is often recommended to aid drainage in heavy soil - how does this work? I guess it would only help in soils which are too acid to start with, as the PH would be altered in the process, correct?

Will a newly planted tree be likely to develop fruits (of any size) during its first couple of seasons, and if so should they be removed?

Is it a good idea to dig the actual planting hole a bit deeper than would normally be required, and put some course gravel or rubble in the bottom, again to create better drainage?

When it comes to pruning, what is the current opinion on the use of wound paints like Arbrex?

Lime will increase the pH. It will not help with drainage. Sand and gravel aid drainage but be careful filling the planting hole with sand/gravel as it may allow the nearby clay to form a virtual pond in the sand/gravel and drown the tree.
Any use of sand/gravel in a clay soil needs to be dug-in over a wide area.
Personally I would go with the soil you have.
Loosen the soil over a few feet area, but stand the tree on top of the ground after digging. Then mound soil over the roots until the roots are all covered. Have the mound at least six inches high and extend at least two feet in each direction (since it will be a big tree it needs room for roots to sit above the water).
The tree is then sitting in a mound and is above the natural soil level, but the soil is loose enough for the tree to grow roots down and outwards.

Crown rot of the smaller roots is not a problem - crown rot is a serious problem if it attacks near the base of the trunk (usually worst when it attacks burrknots up to six inches above or below soil). So a six-inch mound will keep the "weak point" burrknots out of the danger zone.
After several years the base of the trunk will have thick enough bark to prevent burrknots breakout out through the thick bark, so it should become fairly resistant.

For pruning, I would not seal the wounds - I prefer to let them heal naturally. Just keep an eye on the tree. Canker usually starts in a few minor places on twigs, fruit spurs or woolly aphid damaged areas. If you prune the tree annually you should be able to remove any cankers before they spread. The biggest threat to a canker-prone tree is being neglected.
It would seem that certain parts of the UK have KOR-capable canker strains while others don't. Maybe the KOR-canker will never find the tree.

[yummersetter]

Yeah! KOR wins! You won't regret it.

[Philthy]

Quick update:

Friday was supposed to be tree planting day. My KOR was booked for delivery Friday, timed to coincide with the dry and settled weather predicted for the week. I booked the afternoon off work specially, to get the tree in before the weather turned again.

Beginning of the week, with the mild spell developing nicely, I managed to get in a quick mow of the grass on the planting site. Checked the weather forecast; still fine and dry up to the weekend. Wednesday morning, early, I marked out the spot and lifted turf on a 2m sq area. Then I covered the site with a tarp, ready for Friday. Checked the forecast again, still good.

Yesterday, mist and damp for much of the day. And then Friday, the heavens open and constant, at times torrential rain, all day long. My tree arrived no problems, but is right now leaning up against the shed, still wrapped up. So the ground is saturated again, and apparently on Sunday winter is set to return with sub-zero temperatures.

So I guess I ought to 'heel in' the tree now, as I can't see another planting opportunity any time soon. The golden rule for planting any tree, is not to do so if the ground is wet or frozen, correct? I'll put it in a tub with some compost. Is it best to leave the tree outside in the tub, or bring it into a shed during the coming cold spell?

I recall reading on some website that bareroot trees shouldn't be planted once the buds have burst. Is that correct? If so why would that be a problem? I guess I'm running out of time for this season.

Bit frustrated. Thanks