Peach tree in Spain produces lots of sap(?) forms black coating on tiles and attracts loads of wasps. Answer?

Answer 1

Sounds like you may have aphids. Aphids are soft bodied insects that suck a plant's sap. They then secrete a sweet honey dew that drips from the tree. This honeydew can become infected with a black, sooty mold. Control the aphids and you control the black coating and remove the wasps. You can dislodge aphids with a strong steam of water. Insecticidal soaps are a good contact insecticide that is both safe and effective. Some dishwashing soaps mixed with water at a 1-2% solution can also kill aphids on contact, but these soaps may be phytotoxic and can burn the leaves. Always test a homemade soap solution on a few leaves before you apply to the entire plant. For larger trees, there are systemics that can be applied to the roots of trees and translocated to the leaves that will control aphids.

Additional Details: The insects producing the honeydew could also be mealybugs, scale or whiteflies.

Answer 2

A Well Lit is right, but honeydew (bug poop) can be produced by scale insects and whiteflies too. If aphids were causing the problem you would have probably noticed them. But often scale just look like tiny turtle shells stuck to the bark of the smaller branches, and might be missed by the uninitiated gardener. For scale insects, their "turtle" shell provides a measure of protection from most insecticides and home remedies, so you really need a systemic insecticide which the plant roots can take up into the plant sap that the scale insects are drinking. In the US Bayer sells a systemic insecticide containing Imidocloprid. Another brand name for it is Merit. It will kill scale insects (about the only thing that will), and other detrimental chewing and sucking insects, without harming most beneficial insects. It is also among the less dangerous insecticides to mammals like humans. I do not know if it is available in Spain
Whiteflies are identified as tiny white insects that rise up like a cloud when you disturb a branch. I am not sure if Merit works on them. Anyway, they too are very difficult to get rid of. I would say introducing their natural predators into your yard would work the best if whiteflies are the problem.

Answer 3

chop the tree down

Answer 4

wash it off