What is "plant disease"?

"Plant disease" refers specifically to a condition in plants that is caused by pathogens. These pathogens can include various biological agents such as bacteria, fungi, viruses, and nematodes. The definition emphasizes that these diseases result from the invasion of these harmful organisms, which disrupt normal physiological processes in the plant, leading to symptoms such as wilting, discoloration, or reduced growth.

Identifying plant disease in this context is crucial for effective diagnosis and management. Understanding the role of pathogens is foundational for developing treatments, implementing proper care, and conducting pest management strategies to protect plant health. The other options do not capture the specific nature of plant diseases in relation to pathogens—environmental conditions or beneficial traits do not constitute diseases, and phenomena affecting reproduction are not classified under the standard definitions of plant disease.