Which of the following is a sign of phytotoxicity?

• A. Death of rapidly growing tissues
• B. Pests on leaves
• C. Uniform deep green color
• D. Bronzing of leaves

Answer: (A)

Phytotoxicity is plant injury caused by a toxic chemical, such as a herbicide or salt, that disrupts growth and tissue function. When the rapidly growing tissues—the meristematic areas where new leaves and shoots form—are exposed to the chemical, they can die because cell division or metabolism in those zones is particularly vulnerable. This results in dead or necrotic new growth and appears as dieback or loss of fresh shoots, which is a clear mark of chemical injury to the plant.

Pests on leaves indicate biotic damage rather than chemical injury. A uniform deep green color isn’t typically a sign of phytotoxicity and can just reflect healthy growth or nutrient status. Bronzing or bronzed patches can be a sign of injury, but the distinct death of new, rapidly growing tissue most directly signals phytotoxicity from a toxic substance affecting meristematic regions.