Berry crops can include a wide variety of plant species, with the most important temperate North American species in the genera Fragaria, Rubus, and Vaccinium. The preharvest factors affecting the postharvest quality of berry crops can be divided into abiotic and biotic factors. Amongst the abiotic factors, mineral nutrition, especially calcium and nitrogen, water, temperature, and light play important roles in postharvest quality attributes such as size, color, firmness, acidity, and sweetness. Amongst the biotic factors, several postharvest pathogens, which are also present as preharvest pathogens, can cause very significant reductions in postharvest quality. Grey mold (Botrytis cinera) is considered to be the most important pre- and postharvest pathogen in berry crops, but other preharvest pathogens (e.g., Alternaria, Colletotrichum, and Rhizopus) can become major problems, depending on other preharvest factors. In some growing areas, the presence of fruit fly larvae in the fresh fruit reduces the postharvest quality. Other biotic factors can be more subtle in their effects on postharvest quality, such as cultivar, pruning, and pollination.