Why have my apple tree leaves got holes?

[Joydeep]

I planted a bare rooted apple tree from bunnings in August. After winter we got lovely green leaves appearing and even flowers which did not fruit thiugh. The tree was happy and healthy, however in the last two months all the leaves have developed holes. I am not sure if this is any fungal infection, rust, frog eye spot or simply caterpillar attack. The tree is still growing new leaf buds. I have attached picture. We are in Southeast of Melbourne in Cheltenham. Kindly help. I absolutely love this tree as my baby and I feel sad not able to do anything. To note, Off late there has been a great infestation of caterpillar in this region and they have also attacked other plants in my garden, so wondering if that is what it is.

 

[MitchellMc]

Welcome to the Bunnings Workshop community @Joydeep. It's wonderful to have you join us, and many thanks for your question about Apple care.

I really can't put my finger on what exactly the issue is there. I don't believe it's frog eye spot as that has a very specific "frog eye" look to the blemishes. Although the holes do look a bit like chew marks I suspect they're not. The only disease I've encountered that incurs similar leaf damage is Apple scab. 

Let me mention a couple of our knowledgeable gardening experts @Noelle and @mich1972 to get their thoughts.

Please let me know if you have any questions.

Mitchell
 

[Noelle]

Hi @Joydeep 

I have to agree with @MitchellMc that the damage on your leaves is certainly not typical of caterpillar incursions!  The brown spots don't show signs of chewing at all.

I'm not sure it is apple scab as that usually causes distortion of leaves and starts with a spot that then spreads and merges with surrounding spots so eventually there's a large brown/black area that, on the underside of leaves, looks velvety. I do think, however, it is a disease, most likely fungal and quite possibly alternaria.

Alternaria is most often associated with brassicas (cabbages, caulis, sprouts, kale) so if you are growing any of them, or your neighbours have them growing, then that's a possible source of infection.

Treatment of the apple tree begins with a copper-based fungicide applied over the entire tree as soon as the leaves fall in autumn, followed by a second application just as the buds start to swell (but before leaves or flowers open) in late winter / early spring.

[MitchellMc]

It's great to see that @Noelle has provided some excellent information, @Joydeep. Here's a suitable copper-based fungicide.

Please keep us updated.

Mitchell 

[Joydeep]

@Noelle  thanks so much. Will it be ok if I apply the copper fungicide now? Or do I need to wait till Autumn as you have said. I am just a bit worried that since Autumn is still quite far off (at least 2 more months) will the tree be able to tolerate the damage till then

[Noelle]

Hi again @Joydeep 

The damage has been done for this year - the disease is not going to affect the tree any more than it is at present.  The tree itself has done its main job for the year - it grew leaves and flowers (although you didn't get any fruit, possibly due to lack of pollinators or maybe the tree is still quite young) and it has grown. Its next task is to shed its leaves in autumn.

The timing of the application of the fungicide, in autumn, is to protect the over-wintering buds and to kill any fungal spores that may be sheltering in the bud scales.  You need to wait until the leaves have fallen - possibly around mid April - because those buds have not yet developed sufficiently.  There is no benefit to be gained from spraying now.  The aim of the autumnal spray is to kill mature spores and so prevent infection next spring, when the buds start to swell.