As wireworms spread across Prince Edward Island, costing potato growers millions of dollars by damaging crops, farmers are turning to a new rotation crop for the fight. Wireworms, the larval form of the click beetle, have become a serious agricultural pest on the Island in the last couple of years. Brian Beaton, potato coordinator with P.E.I. Department of Agriculture, said the problem is spreading to other crops as well. Beaton said thousands of hectares of brown mustard have been planted this year as part of the battle against wireworm. Last year just a few hundred hectares were planted.