How are infectious plant diseases different from noninfectious plant diseases?

In the field of plant pathology, plant diseases are primarily classified by their causal agent as either infectious or noninfectious. The fundamental difference lies in the nature of the agent and its ability to spread.12

Infectious Plant Diseases

Infectious diseases are caused by pathogenic organisms, such as bacteria, fungi, viruses, viroids, mycoplasmas, nematodes, or parasitic flowering plants. These agents are capable of reproducing within or on a host and are transmissible from one susceptible plant to another. They often require specific environmental conditions, such as moisture or temperature, to successfully invade and infect plant tissues.123

Noninfectious Plant Diseases

Noninfectious diseases are not caused by living organisms and are therefore not transmissible. They result from unfavorable environmental or physiological conditions, including:2
* Environmental factors: Extremes in temperature, improper light, poor air circulation, or unfavorable soil moisture-oxygen relations.42
* Nutritional imbalances: An excess, deficiency, or unavailability of essential soil minerals.42
* Chemical injury: Exposure to pesticides, air pollutants (such as ozone or sulfur dioxide), or other toxic substances in the soil or atmosphere.452

While noninfectious agents are not transmissible, they can weaken a plant, making it more susceptible to secondary infections by pathogens.42