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ARS Home » Northeast Area » Frederick, Maryland » Foreign Disease-Weed Science Research » Research » Publications at this Location » Publication #419403
Research Project: Integrative Genomic and Biological Approaches to Detect and Manage Emerging Foreign Fungal and Oomycete Plant Pathogens

Location: Foreign Disease-Weed Science Research

Title: The effects of sanitizers on Calonectria pseudonaviculata and C. henricotiae conidia and microsclerotia viability

Author
item Shishkoff, Nina
item LAMONDIA, JAMES - Connecticut Agricultural Experiment Station
item COWLES, RICHARD - Connecticut Agricultural Experiment Station

Submitted to: Journal of Environmental Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2025
Publication Date: 7/3/2025
Citation: Shishkoff, N., Lamondia, J.A., Cowles, R.S. 2025. The effects of sanitizers on Calonectria pseudonaviculata and C. henricotiae conidia and microsclerotia viability. Journal of Environmental Horticulture. 43(2):83–90. http://meridian.allenpress.com/jeh/article-pdf/43/2/83/3522793/i2573-5586-43-2-83.pd.
DOI: https://doi.org/10.24266/0738-2898-43.2.83

Interpretive Summary: Boxwood blight is a disease that threatens boxwood, a popular ornamental used in historic and home landscapes as hedges, specimen plants and topiary, while cut greenery is sold as wreaths. Annual sales of boxwood in the U.S. in 2014 were approximately $126 million and were part of the $46 million dollars in sales for cut greenery in 2015. Boxwood blight can be spread on landscaping tools and equipment and there is a need to find inexpensive and effective means of sanitizing such items is essential. Previous research here found ethanol to be a rapid and effective sterilant, and this work builds on that research, and includes isopropanol alcohol in tests, since it is more easily available and less expensive. Based on our results, we conclude that ethanol and isopropanol can be used to quickly and inexpensively disinfest tools and contaminated surfaces.

Technical Abstract: The boxwood blight pathogens Calonectria pseudonaviculata (Cps), and C. henricotiae (Che), produce microsclerotia (ms) on and in leaf tissue and conidia in sticky masses that can be spread by equipment and tools. We evaluated the effects of sanitizers on conidia, excised ms or all Cps life stages in 4-mm-d leaf disks. Leaf disks and excised ms were exposed to sanitizers or water for 3 to 180 min (disks), or 0.5 to 30 min (ms), wicked dry and placed onto half-strength PDA to determine viability. Conidia were loaded onto a filter, exposed to alcohol concentrations for between 2 s to 2 min and rinsed with water. Filters were backwashed with air to transfer conidia onto water agar and the percent germination was counted after 24 h. Cps in leaf disks was killed within 10-12 min for 70% ethanol and between 2-3 h for 0.525% NaOCl. Chlorophenol did not eliminate Cps from tissue. Individual ms were killed by 70% ethanol in 4 min. In contrast, ms exposed to 0.525% NaOCl or 0.05% chlorophenol for 30 min retained viability. Conidia of Cps and Che exposed to 10%, 25%, 40% and 70% ethanol demonstrated no germination after 20 s in 25% ethanol or 5 s for 40% and 70% ethanol. Conidia of Cps and Che exposed to 70% isopropanol were also dead within 5 s. A dose-response study for ethanol and isopropanol estimated 99% mortality from exposure to 63.6% alcohol for 2 s, with no difference between the alcohols. We conclude that ethanol and isopropanol can be used to quickly and inexpensively disinfest tools and contaminated surfaces.