Marginal necrosis
The name marginal necrosis or tipburn refers to two types of abiotic problems (physiological and non-parasitic), affecting lettuces cultivated in soil as well as off soil. They are manifested by necroses starting at the edge of the leaves of the heart or crown of lettuces, and seem to be caused by a combination of genetic and environmental factors, more or less related to calcium and in particular its transport in plants.