Yellow spots on leaves

This week I noticed some yellow spots appearing on a few leaves on some of my deciduous trees...







Anybody with similar problems, or knows what could be the reason? Could this be from fertilizing too much?

Kind regards from Belgium,

Hans

Hans, have you been treating for fungus?

I was hoping for someone more knowledgeable would reply.
The damage from the leaf looks like two different problems.
First the round wounds/lesions in the field of the leaf and second the areas around the veins.
They could both be fungus, but the round spots in the field of the leaf would make me think of an airborne problem.
The other along the veins might be systemic, that is, an infection of the vascular system of the tree.
The airborne problem might defoliate your tree in the long run but will probably not kill it.
The vascular issue could be fatal.
I am not sure what to recommend. I would use a product called Subdue in granular form.

Orion wrote:Hans, have you been treating for fungus?

Yes,

I live at the edge of a small forest, so I do a lot of preventive spraying against fungus and needle cast. This year I have already used these products:

- 15/03 Dithane Neotec 4 gr/liter
- 11/04 Cupravit Forte 4 gr/liter
- 29/04 Dequiman 3 gr/liter

I also sprayed against insects and spidermites with products like Baythroid, Masai and Confidor. So normally there should not be a problem with insects. We also had warmer than normal temperatures over here, and almost no rain at all, so a fungus attack seems also almost impossible to me. There are a lot of types of insects flying around over here, probably by the warm weather over here. But I can not find them on the trees. That's why I am thinking about over-fertilizing...

Regards,
Hans

That's a lot of different chemicals you're using Hans. I would swear from the first photo it's a fungus. The spores overwinter and it starts up in the spring. You mentioned the possibility of over-fertilizing, what are you using?

The spots do not look anything like fertilizer burn. They are probably from a bacterial or fungus infection. Is there a university near you with a botany department, an agricultural school, a professional arborist, or a large, well-staffed garden center? One of them could help you. If you are spraying with a fungicide & the problem becomes worse, it is probably a bacterial infection, which is generally untreatable. Give your trees more sun and more air circulation, and get rid of the infected leaves, preferably by burning.
Iris

As fertilizer I use Abrakas & Tamahi as organic fertilizers, and I also use Fish emulsion, Bio Green, Bachumus, and some products from the Sumo range...

@ Iris: I have a department of research in plant diseases in the neighbourhood, but I heard it is pretty expensive letting them examine your plants.

Could this be a form of chlorosis?

For the browning that seems to follow the veins, consider Anthracnose -- especially if the weather has been wet.

Remove and destroy the leaves. Lime sulfur applies early in the spring can help prevent it.

The round circles with dots in the middle is a rust of some sort; they are nearly identical to the spots caused by cedar apple rust on apple leaves, but maples are not susceptible. But treat it as a rust fungus.

Hello Hans. I think I would bite the bullet and get those leaves checked over by a specialist. Especially if they are expensive or sentimental trees. There seems little point in throwing chemicals over them if you don't know what your treating. An airborn fungus sounds dubious to me, especially as you say you've had no significant rain. Same here by the way.

Hans, hope by this time you have already solved the problem.
I have some off-topic question about Tamahi fertilizer: how has it been working for you? does it smell? does it attract critters and worms? any fungus activity after application?
Any experience and information regarding this fertilizer would be much appreciated.

It could also be a sucking insect sitting underneath the leave, like white fly or scale. It could also causes discolouration of the leave.

I have a problem with wild olives in the nursery looking like that, it was both whitefly and scale.

a systematic insecticide will take care of it.

Love and light

I just noticed it was 2 years ago....  

What was it? now that this is revived?