There are many reasons that plants die and some of the reasons are not related to disease. A lot of environmental stressors cause disorders that look like, but are not diseases. An example of an environmental stressor is drought. Drought stress can kill a plant. When a pathogen infects a plant and disrupts growth that causes the disease. The disease can ultimately kill the plant. The most common plant pathogens include fungi, bacteria, and viruses.
The following environmental factors can affect disease development:
- Temperature – Fungal diseases occur over a wide range of temperatures.
- Moisture – High relative humidity favors fungal pathogen growth.
- Wind – Wind increases the spread of plant pathogens and the number of wounds on host plants.
- Wounds – Pruning and hedge trimming can create wounds that allow pathogens to enter a plant.
- Host – All plants are not susceptible to all pathogens; each pathogen has a host range.
- Soil Type – Sandy soil can stress plants because of its low moisture-holding capacity, while a high clay level can cause stress because of its excessive water-holding capacity.
- Fertility – Low fertility causes stress, while excessive fertilizers can provide a flush of growth that is more susceptible to disease.
- Light – Insufficient light can favor certain diseases.
- Herbicides – Herbicides can increase the severity of certain diseases.
- Air Pollutants – Air pollutants can cause direct symptoms on the host and affect the pathogen.
Because of the wide range of problems that occur on the many plants in a landscape, determining which disease is affecting the plant or turfgrass is often difficult. Correctly diagnosing disease problems is critical because treatment recommendations are vastly different for different disease problems. To properly diagnose a plant disease problem, homeowners can
- consult a lawn and landscape professional,
- consult a Master Gardener or other knowledgeable plant person,
- contact their county Extension agent for help, or
- submit a sample to the UF IFAS Extension Plant Disease Clinic (http://edis.ifas.ufl.edu/SR007).
Once the cause of the problem is known, homeowners can work with a lawn and landscape specialist to determine how to manage it and prevent the problem from recurring in the future.
Lawn disease control