Nursery and Flower Grower

The disease triangle is a fundamental principle illustrating the factors involved in the occurrence and severity of plant disease. Disease caused by a living agent requires the interaction of a susceptible host, a virulent pathogen, all in the context of a favorable environment.

Plant diseases their occurrence and severity result from the impact of three factors: the host plant, the pathogen, and the environmental conditions. This is represented with the disease triangle. If any one of the three factors is missing, the triangle is not complete, no disease will occur.

As you walk quickly down the nursery walkway on the way to the sales team meeting, you glance over at the 1- gallon stock that's almost ready to sell. Then you stop; something is wrong with the Chamaecyparis lawsoniana. Yikes, the older portions of the branches are browning on many plants.

The majority of fungi, aerial nematodes and bacteria that cause plant diseases require liquid free water on the plant surfaces before they can infect the plant. Free water, sufficient for disease infection, commonly occurs in the form of rain, fog, and dew.

Good air circulation in a crop canopy has many important positive impacts. As described in previous blogs, carbon dioxide utilization and consequently photosynthesis is improved.