Shortages of iceberg lettuce and other vegetables may continue into March as poor weather in the south of Spain persists, Spanish farmers have said.The southern region of Murcia, where most Spanish lettuce grown for export is cultivated, suffered the worst floods in two decades followed by its first snow storm in over 30 years in December and January.Supermarkets across the UK are rationing customers to three iceberg lettuces per visit.Farmer and manager of the local producers' group, Fernando Gomez, said: "We have notified our customers that there may be production delays in March because the planting of seedlings has been delayed and in the rush to supply the market some crops were picked ahead of time."Bad weatherVegetable production in the European Union has fallen to 60 percent of normal levels in recent weeks due to bad weather affecting producers across the Mediterranean, from Greece to Spain. Spain accounts for around half of EU vegetable exports.Many farmers in the area do not insure their crops. In a sector with very slim profit margins of between 1.5 and 4 percent, profit relies on big volumes. Higher prices have not made up for the losses farmers have suffered.Fernando Gomez, manager of fruit and veg export group Proexport said: "Some other supermarkets in the UK have the products, because we are delivering them, like we do with the rest of our clients in the rest of the world, and they have them available to be sold to the consumers."There are no problems in Germany, there are no problems in Spain, neither in France, and in the English supermarkets that bought their lettuce with the proper market rate, there are no problems either."