CANADA STOCKS-TSX falls as financials and resource stocks slide

(Adds portfolio manager comments, details on Canadian Western Bank; updates prices) * TSX closes down 157.95 points, or 1.14 percent, at 13,707.68 * Index touches its lowest since April 18 at 13,599.93 * Eight of the index's 10 main groups end lower By Fergal Smith TORONTO, May 3 (Reuters) - Canada's main stock index fell to a two-week low on Tuesday as lower commodity prices weighed on energy and materials stocks, while financials dropped after Canadian Western Bank set