2 weeks ago I bought a Ulmus Parvifolia. I live in The Netherlands and the ulmus is outside. Now it has small white flies on it, I sprayed it with Pokon Bio-Insect 2 days ago, but with no results yet. The leaves are turning yellow and start dropping off. I also noticed that when I water the ulmus, the soil is getting dry fast, the soil isn't retaining water. What should I do?

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