Diseases in plants are caused by biological agents known as what?

Diseases in plants are primarily caused by biological agents referred to as pathogens. Pathogens include various microorganisms such as fungi, bacteria, and viruses that can infect plants and lead to disease symptoms like wilting, necrosis, and stunted growth. These agents disrupt the normal physiological functions of the plant, often leading to significant agricultural losses.

In contrast, insects, while they can cause damage to plants and sometimes transmit diseases, are not the specific agents that induce disease at the biological level. Similarly, parasites generally refer to organisms that live on or in a host organism and derive nutrients at the host's expense, which can include some pathogenic interactions, but the term is too broad when discussing disease causation in plants. Pests, on the other hand, encompass a broader category including insects, weeds, and other organisms that cause harm to plants, but like parasites, they may not specifically denote those that cause diseases. Thus, pathogen is the most accurate term for the biological agents responsible for plant diseases.