Activating Disease Resistance in Turfgrasses Against Fungal Pathogens: Civitas and Harmonizer

Abstract

When Civitas, a mixture of isoparaffins with an emulsifier, was sprayed onto turfgrass in the field, it significantly reduced several turfgrass diseases. However, Civitas showed little direct antimicrobial activity. In the laboratory, Civitas made leaves more resistant to fungal pathogens even when applied to soil without contacting the leaves, thus indicating that a type of systemic induced resistance had occurred. Expression patterns of several marker genes for ISR in Agrostis stolonifera showed that all were primed by Civitas for stronger expression following inoculation. These genes were also primed following treatment with (2R, 3R)-butanediol, a known ISR activator. Thus, Civitas appears to activate ISR. Harmonizer is a polychlorinated copper (Cu) II phthalocyanine that provided control of dollar spot when sprayed in the field. Although Harmonizer showed some direct effects on fungal growth, it also reduced foliar infection in the laboratory when directly applied to soil avoiding direct contact with the pathogen. This indicated a type of systemic induced resistance. Expression patterns of several marker genes showed that Harmonizer was not activating ISR or SAR. Next-generation sequencing was then employed to examine large-scale gene expression revealing that Harmonizer induced expression of defense-related genes in plant parts not treated with Harmonizer. Although the mode of action of Harmonizer has some overlap with SAR, it does not exactly follow that of either ISR or SAR activators.