Cheap bananas on supermarket shelves threaten the livelihood and well-being of banana growers across the developing world, campaigners will tell directors and shareholders today...when they meet for the annual general meeting of supermarket giant Sainsbury...In Costa Rica, for example, the persecution of workers trying to join trade unions on plantations that supply Sainsbury continues unabated...The workers are also exposed to powerful pesticides, some of which are used to meet the cosmetic appearance requirements set by the supermarkets. [refers to price war led by supermarkets Asda & Tesco]