The white marks you can see are residues where the product has evaporated from a hard surface. If the product is over-applied to a hard surface it can build up and then crystalise as it dries. Please be assured that there is nothing in this product to leave permanent stains or discolour hard surfaces. The crystals you can see will naturally break down and soon disappear, rainfall and sunlight will speed the action up.
It is important when using any garden product that you apply in full accordance with the instructions, this will include the distance to spray from and advice regarding how to spray for example, spray lightly - avoid surface run-off. When these instructions are followed the product will not be applied heavily enough to build up and cause any visible residues.