Which outcome is most associated with stressed plants?

• A. Plants are more susceptible to insects and disease
• B. Pest pressure decreases
• C. Pest avoidance increases
• D. Stress improves pest resistance

Answer: (C)

Stressed plants commonly bolster their defenses to minimize damage, so they tend to become better at avoiding pests. When a plant experiences stress or grazing, it activates defensive signaling—especially jasmonic acid and ethylene pathways—that switch on both chemical and physical barriers. This can mean tougher tissues, production of deterrent chemicals like phenolics, alkaloids, or tannins, and the emission of volatile compounds that repel insects or attract natural enemies of the pests. All of these responses push the plant toward avoiding pest attack rather than simply tolerating it.

While stress can sometimes coincide with increased susceptibility or yield mixed results, the typical and most consistent outcome described in greenhouse practice is an increase in pest avoidance due to these induced defenses.