Last Year’s Ornamental Diseases Equal This Year’s Disease Risk

Disease presence last year can indicate a risk for the same disease this year. Many pathogens overwinter on infected plant material or as pathogen survival structures. Poor sanitation practices can lead to an increased risk of these diseases in the upcoming season. A summary of ornamental samples submitted to University of Kentucky Plant Disease Diagnostic Laboratories in 2019 are displayed here. The most common diseases of herbaceous ornamentals were root, stem, and crown rots (Pythium, Phytophthora, Rhizoctonia, Thielaviopsis, anthracnose) and foliar blights (Rhizoctonia, Botrytis, Phytophthora, Phoma, and other misc. fungal diseases) (Figure 1). In woody ornamentals (trees and woody shrubs), the most common diseases were leaf spots (including anthracnose, powdery mildew, and other misc. fungal diseases) and canker diseases (including Volutella canker) (Figure 2).

Figure 1: A summary of herbaceous ornamental disease samples submitted to UK Plant Disease Diagnostic Laboratories in 2019.

Figure 2: A summary of woody ornamental samples submitted to UK Plant Disease Diagnostic Laboratories in 2019. Phytoplasmas, fungal and bacterial gall diseases, and virus diseases were also diagnosed on woody ornamentals in 2019. Each group represents less than 1% each of the total woody ornamental disease samples and are not included in the pie chart.


Assessment of diseases likely to occur during the growing season provides the opportunity to utilize preventative management measures. The University of Kentucky Plant Pathology Department provides numerous publications with additional information and management options for these diseases. County Extension agents also provide information on disease diagnosis and management.



By Kim Leonberger, Extension Associate and Nicole Gauthier, Extension Specialist


Posted in Ornamentals