Modern senses (method, art, technique) all read shù. The character has a second reading zhú used only in a small set of traditional-medicine plant names - 白术 and 苍术, rhizomes used in Chinese medicine. If you are not in a TCM context, default to shù.
The tree radical forms the body. 术 originally referred to a kind of plant (atractylodes); the wood-radical is the lingering trace of that botanical sense. The full simplified form merges 術 (technique) into 术, giving the modern 'art/method' meanings.
A small dot in the upper-right corner - an abstract differentiating marker that distinguishes 术 from 木 and 本. It carries no real-world depiction; it is purely a position-marker pinning this glyph apart from its tree-family neighbours.
