John Bishop Sharks head coach John Plumtree says he will suspend his players if they are yellow-carded in future Super 14 games.Plumtree was reflecting on his team’s 25-21 loss to the Waratahs in Sydney when two Sharks players, prop Jannie du Plessis and flyhalf Andy Goode, were sin-binned in the first half. The Sharks have now had five players yellow-carded in four games and Plumtree said this was unacceptable.“I was very annoyed with our discipline and have been for a while,” Plumtree told the Sharks website. “I read the riot act to the guys in our post-match analysis on Monday night.” Plumtree said he would take action against players who are sin-binned in the future.“I told the guys that the next player to get a yellow card gets a red card from me. When you are down on your luck, and trying really hard to get out of a hole, you can’t then make it tougher for the team by getting yourself binned. It is just silly and stresses the team unnecessarily. “This has been creeping into our game now for a while and it has to stop right now. We were always a side that prided itself on discipline both on and off the field.” The Sharks met the Brumbies in Canberra on Saturday and then head back across the Tasman ea to New Zealand to play the Hurricanes and Highlanders in their last two tour games.Plumtree admitted “the big decisions” that had gone against the Sharks in the final three minutes – the knock-down of Stefan Terblanche’s pass and the penalty for lineout obstruction - had “seriously cost us”“Everybody has been talking about the slap-down of Stefan’s pass to Ryan which would have been a try but for that act of cynical play from Kurtley Beale. There was also a pass to Bismarck du Plessis that was called forward which on analysis was shown to be legitimate and again we would have scored.”He added that there are decisions in rugby that can be controlled, like discipline, and others that are beyond the players” control.“We have to move on from decisions that don’t go their way and which crop up every now and again and are a part of the game. “It happens and we are not focusing on it in our post-match analysis.” From the playing point of view he said there were signs that the Sharks were starting to improve but they were still not accurate enough. “If you can keep hold of the ball and remain accurate with it, enough to take advantage of the quicker ruck ball, you can really put the opposition under immense pressure and eventually tire them out.” He was also encouraged by the character in the team which had seen the Sharks fight back from 25-14 down against the Waratahs to almost win the game. “We will just carry on fighting until we get that first win and hopefully then get on a roll.” The Sharks have been boosted by the arrival of tall lock Alistair Hargreaves as back-up to Johann Muller and Steve Sykes but flank Keegan Daniel could be ruled out of Saturday’s game with concussion.Daniel took a knock to the head against the Waratahs and will undergo a concussion test later in the week.Wing Odwa Ndungane is also being troubled by a slight hamstring strain.Saturday’s match against the Brumbies is at 10.40 am and will be handled by rookie New Zealand referee Garrat Williamson, who is from SANZAR’s reserve panel.