Apple Scab

[FB.]

I have been growing quite a few apple varieties in recent years.
Generally, their disease resistance matches with what "the experts" and publications say.

But I have a few anomalies and was wondering if others have seen the same.


The main anomalies centre around scab and are:

Bramley
Supposed to be scab susceptible.
Mine seems to be resistant.

Fiesta/Red Pippin
Supposed to have no particular disease resistance.
Mine seems resistant to scab (and mildew).

Golden Delicious
Supposed to be scab resistant.
Mine is scab susceptible.

James Grieve
Supposed to be scab susceptible.
Mine is scab resistant.

Pinova
Supposed to be scab resistant.
Mine is scab susceptible.

Spartan
Supposed to be scab resistant.
Mine is scab susceptible.

Worcester Pearmain.
Supposed to be scab susceptible.
Mine is scab resistant.


Defining "susceptible" and "resistant" is not as easy as it might sound.

For example.....

Both my Golden Delicious and Spartan had a large number of scab lesions all summer, but the lesions all appear to be small - as if the scab was fought off.

My Pinova has some scab, but it's limited to extensive scabbing of a small number of leaves - as if most leaves resisted attack, but those leaves that were infected were overwhelmed.

So, perhaps Golden Delicious and Spartan do have resistance - but in the form of fighting off an attack on the leaves AFTER the lesions start to form.
Whereas Pinova resisted attack on most leaves, but the small number of leaves and shoots that got infected were extensively damaged.

Perhaps the resistance or susceptibility may be dependent on the particular strains of scab present in the local area?
There are plenty of crab apples in nearby streets or gardens, most of which are severely scabbed, so there's no shortage of scab spores around.

Has anyone else had such anomalies with their apples - or anomalies that don't match my findings?

In fact, listing any scab observations would be useful.....

Thanks
FB.

[littlemark]

I have experience of Spartan and James Grieve this year (a very bad year for scab as I'm sure you know), both of which have been very scab resistant up to now. The JG is located almost under a much bigger cooker which we think is Bramley, but may be Blenheim, and most apples on this tree have moderate scab blotches.

I've just picked up a batch of organically grown apples from the Oxfordshire/Northants border, Fiesta, Gala, Katy, Ribston Pippin, Ashmeads Kernal, Lord Lambourne, Worcester Pearmain, and Elstar; and despite sulphur sprays they are pretty much all affected by scab. This is cull fruit though, so perhaps this gives a false impression of the full crop.

Mark

[daylily]

All apples can get scab as far as I'm aware.

[FB.]

All apples can get scab as far as I'm aware.

Agreed, but some get it much worse than others.
If they only get light scabbing (small spots and not many of them), I tend to consider them to be resistant.
Some varieties seem to get lots of very tiny spots that are so small as to be barely noticeable - it's as if they have defensive activity to limit the spread of the scab. I consider them to be resistant.
Some varieties end up with whole leaves destroyed from just one or two spots of scab that completely overwhelm the leaf. They can get it so bad that they drop most of their leaves, weakening the tree.