Disease is present most of the time, but the right conditions have to be met for it to become an epidemic in the lawn or garden. This article will look at the four factors that are required for an epidemic to occur. The four factors are host plant, pathogen, favorable environment, and means for pathogen to spread.
Host plant: The host plant is the plant that is susceptible to the disease. For an epidemic, it needs to be present in large numbers. It can be a monostand such as a lawn, farm, or tree plantation, or it can be a common plant such as maple in a forest comprised of maples, oaks, and ash.
Pathogen: The pathogen is the disease itself. There cannot be an epidemic without a disease nor can there be an epidemic without the host plant. But a disease can’t just become an epidemic by itself, fortunately. It needs the right conditions and the ability to spread.
Favorable conditions: A disease can often survive in a broad range of conditions, but needs a perfect mix of conditions to become rampant. Natural conditions include temperature, level of moisture, lack of ventilation, and lack of sun. Some diseases will not do well if it is too cold or too warm. Others explode if conditions are excessively moist, such as on wet cloudy days. Watering practices can help or hamper diseases. Fertilizing can affect growth and make it more susceptible or less susceptible to disease.
Means to spread pathogen: The spores of the disease need to be able to spread from one plant to another plant. Common means include water, wind, and human or animal activity. If conditions are not right, the disease can flourish on one plant but not be able to spread well. Human activity that spreads disease can include poor waste management practices and common practices such as mowing the lawn.
The key to prevent an epidemic is to know what diseases affect the plant, know the conditions ideal for the disease, and know how the disease spreads. Then try to prevent these conditions from happening and when conditions are present, prevent activities if possible that can spread the disease. That way, the epidemic can be less likely to occur.