What kind of symptom does browning or dieback across the leaf surface represent?

Browning or dieback across the leaf surface indicates necrosis, which refers to the death of plant tissue. In this context, the browning indicates that the cells in those areas of the leaf are no longer living, leading to tissue death. This can occur due to various factors such as disease, environmental stress, or nutrient deficiencies. Necrosis manifests visibly as dead, brown areas on the leaves, where the normal green coloration has been lost, causing a stark contrast and indicating that the leaf is not functioning as it should.

The other symptoms, while related to plant health, have different meanings. Chlorosis refers to yellowing leaves caused by insufficient chlorophyll, often due to nutrient deficiencies or lack of sunlight. Wilting describes a loss of turgor pressure in the plant, resulting in drooping leaves and stems, which may indicate water stress. Scorching entails browning at the edges of leaves due to excessive heat or water loss but does not indicate the entire leaf area is dead, unlike necrosis. Therefore, the identified symptom of browning or dieback aligns accurately with the definition of necrosis.