Thank you John,is it enough to spray the tree only once or is it needed to make more treatments.

Imidacloprid will most certainly kill beneficials, it will decimate any insect that is a pollinator, or feeds on plant foliage. Do not use this when the plant is flowering or will soon be flowering. In a lot of regions its use is regulated and outright banned. Not to mention the toxicity -- this product seeps into groundwater and contiminates large water bodies like the Great Lakes. I do not recommend its use.

You will gain control with horticultural oils and their toxicity is much lower -- both for the ecosystem and humans.

Ok I will see what my local garden center carries because the horticultural laws in croatia are very strict so I doubt that a substance that toxic for the environment is being sold here.

But which horticultural oil do I need to buy could you please give me the exact name.

Indeed, the European Union is imposing a very strict ban on neonicotinoids, including imidacloprid (see http://eur-lex.europa.eu/eli/reg_impl/2013/485/oj).

I'm unsure what brands of horticultural oil are available in Croatia, but any of them will work, and I'm sure they will be available for purchase.

Ok,thank you very much.

Tomorrow morning I'll be sure to buy a horticultural oil and to spray the tree.

I think I see scale too. Do as JohnM says... a multiple and repeated attack approach should work for you. H.O. (and perhaps a direct diluted Isopropyl alcohol wipe) for the scale, fungicide for the funky dark growth, and Imidacloprid systemic... applied as a root drench if you are concerned about the beneficials. Use it according to the label... but with an adjustment according to how much the roots will actually take up.

The EU is overacting in my not so H.O.

That's definitely a scale issue with sooty mold growing on the leaves as a by-product of the scale excrement. The best treatment would be horticultural oil (or neem oil), which has the benefit of not being toxic to beneficials long after you have applied the treatment. Just don't apply oil in hot weather, and that should start to clear up.

-Tom

I was at my local garden shop yesterday and I brought a leaf with me just so I could show them if they aren't familiar with those pests and they said that it is illegal for me to buy the insecticides that I need.Now I am on a wait list to get the insecticides and oils that I need but in 2 weeks I will be able to buy them.They need to be sure that I won't be contaminating anything with the things that I buy.You guys were very helpful,thank you.If only would my country make things slightly less complicated.