UVC (254 nm) and Far UVC (222 nm) Irradiation Affects In Vitro Growth of Colletotrichum sp. Isolates and Their Infection of Detached Strawberry Leaves

Authors

• Barbara J. Smith, USDA Agricultural Research Service
• Blair J. Sampson, USDA Agricultural Research Service
• Warren E. Copes, USDA Agricultural Research Service
• Fumiomi Takeda, USDA Agricultural Research Service
• Wojciech J. Janisiewicz, USDA Agricultural Research Service
• Eric T. Stafne, Mississippi State UniversityFollow
• Hamidou F. Sakhanokho, USDA Agricultural Research Service
• Jennifer B. Carroll, USDA Agricultural Research Service

ORCID

Smith: https://orcid.org/0000-0001-7276-0525; Copes: https://orcid.org/0000-0001-7360-7506

MSU Affiliation

Extension Service (MSUES); Coastal Research and Extension Center; Mississippi Agricultural and Forestry Experiment Station (MAFES); South Mississippi Branch Experiment Station

Creation Date

2026-06-30

Abstract

Conventional ultraviolet C at 254 nm (UVC) and Far UVC at 222 nm (Far UVC) were evaluated as alternatives to fungicides for disease control. Conidia of 13 isolates of strawberry anthracnose pathogens (five Colletotrichum species in two complexes: C. acutatum and C. gloeosporioides) were uniformly dispersed onto agar and irradiated with UVC and Far UVC doses ranging from 52 to 1,248 J·m−2. After 48 h of incubation, a UVC dose of 1,248 J·m−2 and Far UVC doses from 234 to 935 J·m−2 reduced Colletotrichum colony counts to < 10 colonies/Petri dish. Cultures exposed to UVC light followed by 4 h of darkness had lower colony counts than cultures incubated under continuous light. This dark incubation period was not required for Far UVC to obtain optimal lethality, indicating Far UVC irradiation can be applied during the day or night and achieve similar fungal lethality. Inoculation of detached leaves of three anthracnose-susceptible strawberry cultivars with conidial suspensions of Colletotrichum spp. revealed that UV irradiation can affect development of anthracnose symptoms. Leaves receiving UVC doses of 312 and 624 J·m−2 or a Far UVC dose of 467 J·m−2 reduced anthracnose infection with little or no plant injury. A UVC dose of 1,248 J·m−2 and Far UVC doses ≥ 467 J·m−2 inflicted varying degrees of plant injury. Disease control intended to reduce the number of fungicidal applications could be developed with moderate doses of UVC and Far UVC irradiation while slowing the evolution of pesticide-resistant strains.

Publication Date

7-15-2024

Publication Title

PhytoFrontiers

Publisher

American Phytopathological Society

First Page

634

Last Page

642

Creative Commons License

This work is licensed under a Creative Commons Public Domain Dedication 1.0 License.

Recommended Citation

Smith, B. J., Sampson, B. J., Copes, W. E., Takeda, F., Janisiewicz, W. J., Stafne, E. T., Sakhanokho, H. F., & Carroll, J. B. (2024). UVC (254 nm) and Far UVC (222 nm) Irradiation Affects In Vitro Growth of Colletotrichum sp. Isolates and Their Infection of Detached Strawberry Leaves. PhytoFrontiers™, 4(4), 634–642. https://doi.org/10.1094/PHYTOFR-03-24-0016-R