What can cause marginal leaf burn in plants?

Marginal leaf burn in plants can be attributed to extreme drought or bacterial infection because these factors can lead to significant stress in the plant's tissues. During periods of drought, the lack of adequate water supply can impair the plant's ability to transport nutrients and maintain proper cellular function, causing the leaf edges to dry out and turn brown.

In addition, bacterial infections can disrupt the normal physiological processes within the plant. They may cause blockages in the vascular system, leading to nutrient and water transport issues that manifest as marginal leaf burn. This condition reflects the plant's inability to properly manage its resources under stress, resulting in the symptoms observed.

Excessive watering can lead to different issues, such as root rot, rather than leaf burn. High nutrient levels in the soil could potentially lead to other forms of toxicity but are not specifically a direct cause of marginal leaf burn. While too much sunlight can cause leaf scorch, it typically affects more than just the margins of the leaves and usually involves other signs of photoinhibition or heat stress. Thus, extreme drought or bacterial infection is the most accurate cause of marginal leaf burn.