Pub group JD Wetherspoon voiced uncertainty about fourth quarter trading after sales slowed in the last few weeks.Wetherspoon said it had a good February and March, but like-for-like sales in April rose less than a year ago and Easter was below last year.Like-for-like sales in the 13 weeks to April 27th rose 6.2% and total sales increased 10.9%. In the 39 weeks to April 27th, like-for-like sales climbed 5.6% and total sales lifted 9.7%. It said in a trading update: "As a result of the slowdown in sales growth in recent weeks and our strong performance in the final quarter of last year, combined with the slightly unpredictable impact of the World Cup, the company retains an element of caution about the exact outcome for the final quarter, but anticipate a reasonable outcome for the year as a whole."Wetherspoon opened 28 new pubs and off-loaded three since the start of the financial year and aims to open around 45 pubs this year, with about 30-40 new pubs planned next year.It expects tax and costs to rise despite the UK government's decision to cut beer duty in the Budget.The group has been campaigning against tax rises on pubs which it said have not been matched by duty increases on supermarkets, causing unfair competition."The biggest dangers to the pub industry are the VAT and business rates disparity between supermarkets and pubs and the continuing imposition of stealth taxes, such as the late-night levy and increased fruit/slot machine taxes," it said.Shares fell 9.5p or 1.1% to 842.5p in early trading in London.PW