What are the conditions necessary for disease occurrence?

The conditions necessary for disease occurrence are best described by the presence of a susceptible plant, a disease-producing organism, and a favorable environment. This understanding is rooted in the disease triangle concept, which indicates that all three factors must be present for a disease to manifest.

A susceptible plant is essential because if a plant has inherent resistance to a pathogen, it is less likely to develop the disease, regardless of the presence of the pathogen or environmental factors. The disease-producing organism refers to the pathogen itself, which could be a fungus, bacterium, virus, or another type of infectious agent capable of causing disease. Finally, the environment plays a crucial role because certain conditions, such as temperature, humidity, and soil moisture, can either promote or inhibit the growth of pathogens and the occurrence of diseases. This combination of elements is vital to understanding turfgrass health and managing pest outbreaks effectively.

Other options lack critical components needed for disease development, such as the absence of a pathogen, an inappropriate environmental context, or an emphasis on resistance without considering susceptibility or external conditions.