Braeburn Apple Tree looks poorly - Help!

3 more pictures.

The weather may have been wet, but it looks as if your tree is planted up against a wall. The soil at the base of walls can be very dry.

By the way, welcome to the Vine. Whereabouts are you?

Hi rustylady

Yes its planted up against a wall but 6 feet away we also have a Cox apple tree which is doing just fine.

I'm in West Sussex!

Flymo

Picture #1 - possibly fertiliser scorch, possibly scab.
Picture #2 - too far out to see enough detail.
Picture #3 - probably scab
Picture #4 - probably scab
Picture #5 - probably powdery mildew (the white stuff) and scab (the pale brown spots)
Picture #6 - scab
Picture #7 - probably scab
Picture #8 - probably scab

Braeburn - and most of the common supermarket varieties - don't have much disease resistance. Regular chemical sprays are how the commercial growers keep their trees healthy.

Thanks FB!

Whats the best chemical spray to use for these problems?

Flymo

Once infected, the damage can't be reversed by sprays, although further damage will be slowed. The worst-affected fruits may split and rot.
The existing infected leaves and fruits will continue to release spores and risk re-infection (some of the spores will now be scattered in the environment around the tree and may be blown around in the wind to reinfect it).

RHS pages on apple diseases -

Scab
Apple scab / Royal Horticultural Society

Mildew:
Powdery mildews / Royal Horticultural Society

....and probably the next disease you'll face........canker:
Apple canker / Royal Horticultural Society

....and a very destructive and debilitating pest of apple trees, especially young trees; woolly aphid:
http://apps.rhs.org.uk/advicesearch/...e.aspx?PID=724



The best solution - and my solution - is to plant varieties with natural resistance. Many old, rare, near-forgotten varieties have strong natural resistance to pests and diseases; not least because that's how they had to be grown in centuries past.

There are some signs of mildew, and some of the fruitlets have scab, but there are also plenty of healthy green leaves and some evidence of shoot growth. Curled up leaves are possibly the result of the recent cold weather.

Although Braeburn is not a disease-resistant variety, your tree is not doing too badly.

I agree with FB and orangepippin. However, looking at the rather tangled, bushy, many-shoots shape of your tree in the second photo, I wonder if some reformative pruning might help this winter, e.g. a bit of focus in the direction of growth such as encouraging more rapid upward growth of one or two main shoots?

I have got scab on some of my apples. The first to get it, and the worst affected, is 'Egremont Russet', which is odd, because it's the only one of my six varieties which is specifically described as scab-resistant in 'The New Book of Apples'. I suppose "resistant" is not the same as "totally immune", but it's a bit odd that it should be the first and worst affected. However, F.B.'s link to the R.H.S. page, above, doesn't mention Egrement Russet in its list of resistant varieties, so maybe the New Book of Apples is wrong.
Anyway, I'm trying to control it by removing and destroying infected leaves when I see them, and hoping for the best. 'Brownlees' Russet' is the second to show signs, though much more mildly. Are russets generally more prone than other varieties, or is that just a coincidence?

I thought russets were (meant to be) generally more resistant to scab than other varieties, but I'm not speaking with any authority. It would be interesting to see a list of the most common ones scored for scab resistance.

I've been commenting in the last few years that Egremont Russet seemed to be losing its disease resistance - no doubt because it is widely planted because it *was* disease-resistant.

But with organic growers and gardeners embracing the variety, it was only a matter of time before one of the many ER's had a mutant scab spore land on it which started the resistance breakdown.

I lost one of my two ER to canker last year (it was a variety that's supposed to be resistant to canker too). This year my remaining ER is quite scabby on the leaves but the fruit seem OK. ER has always had much more resistance to fruit scab than to leaf scab.

In general, russets are no more or less resistant than the average variety, but the general dislike of russets means they are less common, so there may be less well-adapted diseases around to attack them; my usual comment being "if it's common it will often be, or soon become, sickly but if it's rare it'll often be quite resistant, or take much longer for diseases to break-down the resistance".

I believe that Brownlees Russet originates from Hertfordshire, so there may be quite a lot of trees local-ish to you and the concentration of many of the same variety in one area might mean there are some locally-adapted BR-specific fungal strains around.

I've recently taken to giving the example of my Gravenstein; a variety considered to be disease-prone and widely grown in North America and continental Europe.
But it's very rare in England, and my Gravenstein is therefore proving "highly resistant" (actually it's 100% immune to everything so far) to my local strains of disease, and, being a triploid (with more genetic material to draw on for resistance) and being unlikely to be widely grown in my area, I expect it to remain a remarkably healthy tree.

It's often said - and I think with some justification - that simply having a tough skin, which acts as physical barrier to disease organisms, is an effective way to achieve disease-resistance. Most russets fall into this category ... but russeting can be variable from year to year, and it does not arise as soon as the fruitlet forms so its resistant effect is not apparent until later in the summer.

I'm not entirely convinced by FB's argument that the extent of planting has a big influence of disease-resistance. I do think it is a factor, but one of many. It would require pests to be highly cultivar-specific, which is unlikely - scab spores might find life easier on Galas and Braeburns, but if all that is available is Egremont Russet, they will surely settle for that.

Conversely, if you try planting fundamentally disease-prone varieties like Gravenstein, once the local disease and pest population has got over their initial surprise, I would expect it to succumb quickly.

Egremont Russet has a well-proven track record of good general disease-resistance, and I would expect that to continue. But disease-resistance is not the same as disease-proof. Egremont Russet with scab is not impossible, it is just uncommon.

Various research stations have proven that with today's "monoculture" orchards (vast blocks of thousands of trees of the same variety, on the same rootstock), scab and other diseases have evolved to be cultivar-specific; a "one-trick-pony" which is highly specialised and very efficient at attacking just one variety.

Proof of this has been by taking scabby leaves, or isolating fungi from an orchard of one variety and using them to try to infect an orchard of a different variety; very little scab results from the transfer.

However, a small amount of mutant scab spores are always present among the billions of spores produced each year, and a few of the mutant spores may manage to weakly infect a few of the thousands of trees in an orchard. Through further mutation the scab population gradually mutates and cross-breeds and shifts towards being able to attack the variety which was previously resistant.

Loss of resistance usually takes a few years to several years, and it happens so quickly because as soon as one tree in a monoculture block gets a single scab lesion of a new scab strain, it can rapidly spread to all the other identical trees with identical susceptibility.

The following links (there are many others) give plenty of scientific data to back-up the existence of cultivar-specific, specially-adapted strains or races of scab (and it will also apply to other diseases).


http://www.apsnet.org/publications/p...84n10_1005.PDF

http://www.apsnet.org/publications/P...80n10_1179.pdf

.

So, from the data in table 2 of the first link:

Scab isolated from Golden Delicious was also able to infect Spartan (grade 4 severity), but was unable to infect Belle de Boskoop or Idared (both grade 0 severity).

Scab from Spartan was able to infect Idared (grade 4 severity), but was unable to infect Belle de Boskoop (grade 0 severity).

Scab from Belle de Boskoop was able to infect Idared (grade 4 severity), but was only weakly able to infect Glockenapfel (grade 1 severity) and slightly infect Spartan (grade 2 severity).

So clearly scab from one variety is not necessarily capable of infecting another variety - at least, not until it has mutated.
And the more a variety is grown, the greater the chance that one tree might have a mutant spore land on it which manages to establish a new strain. Once one tree is infected, it will gradually spread to other trees nearby or even some miles away by wind-dispersal.

The less common varieties will provide less opportunities for scab mutants to find them, and will be much further apart across the country, making it more difficult for a tree with broken resistance to scatter the spores to another tree of the same variety.