Apple Disease Pictures (Canker/Mildew/Scab/WAA)

[FB.]

For anyone who is interested, here are some pictures taken in recent weeks, from my own apples. The disease should be near the centre of each picture, to make it easy to see.

More and better pictures are avilable further down the topic.......




Canker (note sunken, red-ish bark):




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Powdery Mildew (some apple seedlings - note the white powdery coating, curling/deformation of leaves and gradual death of the leaf - the brown edges)






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Scab (small-medium brown-black spots on leaves/fruit that merge in wet weather):




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WAA <woolly apple aphid> (clumps of cotton-wool-like material on branches/stems/pruning cuts resemble moulds but actually contain aphids):

[BFG]

Thanks. Very useful.

[pdblake]

Intersting, thanks. I notice you have some seedlings there. Just how do you go about growing them?

[FB.]

Intersting, thanks. I notice you have some seedlings there. Just how do you go about growing them?

The pips need to be separated from the core of the apple and then chilled below 7'C (a 4'C household fridge will do) for about a month. Separating form the core before chilling tends to improve germination.
Then plant into pots and wait for the seeds to sprout.

The seedlings will be very variable in their features - size, shape, disease resistance etc. They will usually take years to reach cropping age and may grow considerably larger than grafted apple trees.

Many supermarket apples can grow their pips with no chilling needed, since they will have been stored for months in a cold store. But extra chilling would still be helpful for better germination.

Seedlings will have an unknown father, which could easily be a crab apple pollinator - as used in many commercial orchards. Such parentage could seriously spoil your chances of a good sized and nice tasting apple from a pip.

I grow my pips for grafting experiments and rootstocks - not in the hope of finding a great new variety. I am working on a couple of projects (I'll spare you the boring details), due to the very difficult fruit-growing conditions in my area (difficult if you don't spray and don't irrigate).

At some point in the future, I plan to start making careful crosses of my old-fashioned, tasty and disease-resistant apples.
I will know both parents and I will have an idea of what features many of the offspring will have; "offspring tend to resemble their parents" - said one great genetics scientist.

[StephenH]

So now I know what my tree's got: wooly aphid. Thanks.
Next question - how do zap them organically?

[pdblake]

I think I might have a go at that. I don't mind if I get a crab apple to be honest, they can always go in the chutney

[FB.]

So now I know what my tree's got: wooly aphid. Thanks.
Next question - how do zap them organically?

WAA are troublesome for two reasons:
1: they make wounds which cause knobbly branches and allow canker to enter.
2: the woolly coating is non-living and therefore gives them good protection from sprays.

The rootstocks prefixed with "MM" are fairly resistant to WAA, but they are fairly vigorous.
MM106 is very easy to find. MM111 is harder to find. The other MM's are very rare.

WAA also attack the roots and can cause stunting of the tree (apparently WAA can travel as deep as 4ft below ground) and there is no ability to get those deep aphids, since chemicals won't penetrate far enough down and will be absorbed into the soil.
Aphids on branches are best squashed (it gets messy because they have red "blood") or scrubbed off with a toothbrush. Normally, when WAA populations get noticeably large, small (3mm long) gnat-like wasps will come along and use their sting to inject an egg into the aphids and a tiny wasp develops inside and eventually the aphid bursts and the wasp emerges - like in the film "Alien".
Other predators such as earwigs, hoverfly larva, ladybird larva and lacewing larva may also take their share of the WAA, but it seems as if once one predator type has arrived, other predators steer clear - perhaps to avoid competition, since there are always plenty of aphids to go around.

[FB.]

I think I might have a go at that. I don't mind if I get a crab apple to be honest, they can always go in the chutney

Best that I can suggest is to shop-buy your favourite apple, since half of the genes in each pip will be from your favourite apple. You'll just have to take a chance on the genes provided by the "father" - and hope that the pip got lucky.
Alternatively, find a couple of apple trees near to you and collect some pips (they will probably have pollinated each other, so by tasting the fruit from the trees, you can get an idea what the offspring fruit might be like))

[FB.]

Some more pictures of apple-related problems....

Bitter pit on Ashmead's Kernel (dark sunken spots on -and possibly inside- the apple):



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Apple seedlings severely stunted by powdery mildew:



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A two-year-old apple seedling with a severe area of mildew attack:

[FB.]

Split bark just near to where a leaf joins the stem after (WAA) woolly aphid attack. This wound may well become infected with canker at some point in the future. The leaf has been attacked by a "leaf miner" - as indicated by the swirly brownish trackmark that wanders around the leaf. Leaf miners may be unsightly, but they don't usually cause enough damage to weaken the tree.




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Another picture of damaged bark after WAA attack. Notice the very knobbly appearance along the stem. Many of the lumps will split, literally unzipping the bark along the branch - and exposing the tree to canker attack:

[FB.]

A nasty apple canker in a very inconvenient location. This tree (Ellison's Orange) will need some major surgery during the winter.

[FB.]

...and finally, some nice pictures of scab on fruits and leaves.
The scab usually shows as brownish spots that often split.

Severe fruit scab:





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Moderate fruit scab:



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Moderate leaf scab:


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Mild leaf scab:

[peanut]

Great picks FB.....Now I know for sure my Golden Delicious has Scab, really badly and my Cox but to a lesser extent.

Do you know if GD's are prone to it, if so i may get rid and plant with one that isn't so easily affected?

[FB.]

I think that many of the popular (shop) apple varieties are more prone to disease because everyone want to grow them and therefore the specific strains of scab that attack GD (or Cox, or other varieties) are quite numerous across the UK. Growing more unusual varieties with a reputation for disease resistance can be beneficial.
I grow several russets and although they get moderate leaf scab, the fruits are rarely affected. They also resist mildew and canker quite well, too. Although GD has good resistance to mildew and adequate resistance to canker.
My own GD usually has much worse scab on the leaves than the fruit. It doesn't have many fruits this year, but the fruits have almost no scab, whereas the leaves are quite tatty. But leaf scab doesn't bother me too much.

Have you considered re-grafting your GD? If it has a good root system established, why not make good use of it.
Bear in mind that GD is a very good pollinator for many apples, since it has a very different set of incompatibility genes to most British varieties. Getting rid of the GD may affect pollination of your Cox. I believe that Cox has incompatibility genes 5 & 9 and GD has 2 & 3 - meaning that their is absolutely no genetic factors to block pollination.
If, for example, you grew Kidd's Orange Red instead of your GD, it has the same 5 & 9 incompatibility genes as Cox, so is completely unable to pollinate Cox due to the Cox thinking that the 5 & 9 pollen of Kidd's is from the Cox (apples don't like their own pollen, or pollen that resembles their own).

How about keeping your GD as a severely restricted form such as a cordon, fan or espalier?
The better sunlight penetration and the easier air circulation in and around a cordon allows the fruit to dry faster after rainfall. It also allows better size, colour and taste of the fruit.

edit:
I see that you're in Cambridgshire. If you plan to have a go at re-grafting your GD, I may have some suitable piecies of scion wood during the winter. My apple trees don't grow much, so I don't need to prune all of them every year, but I'll definitely have to prune some of them and you would be welcome to some scion wood - although for about £13, you could buy a new tree from Simpsons Fruit Tree Nursery at Fordham and choose from their good selection.

[tamsin]

I was just going to post about our apple tree. It's produced no apples this year and the leaves are all curly/part brown. There aren't any obvious bugs that I can see.

Any ideas? I doesn't look quite like any of the photos.

Thanks
Tamsin