Aug 30 (Reuters) - Canada's main stock index opened lower on Thursday weighed by worries over Washington's tariff dispute with China, and as GDP data showed the domestic economy grew at a more sluggish pace than expected in June and the second quarter.
* At 9:30 a.m. ET (13:30 GMT), the Toronto Stock Exchange's S&P/TSX composite index .GSPTSE was down 18.61 points, or 0.11 percent, at 16,371.68.