Author ORCID Identifier

https://orcid.org/0000-0002-0086-5368

Year of Publication

2020

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Agriculture, Food and Environment

Department

Plant Pathology

First Advisor

Dr. Lisa J. Vaillancourt

Second Advisor

Dr. Nicole Gauthier

Abstract

Fungi in the genus Colletotrichum cause apple, blueberry, and strawberry fruit rots, which result in significant losses for Kentucky growers. Most orchards in Kentucky are agritourism-focused and grow multiple fruits in close proximity. These mixed-fruit orchards may facilitate Colletotrichum cross-infection, which has serious management implications. Small fruit and apple Colletotrichum isolates from Kentucky orchards were characterized by morphotype, phylogenetic species identification, cross-inoculation, genome sequencing, and telomere fingerprinting. The small fruit isolates grouped into seven morphotypes, representing two species complexes: C. acutatum and C. gloeosporioides. All blueberry isolates belonged to the species C. fioriniae, and the majority of strawberry isolates were C. nymphaeae. Two other species found less frequently on strawberry were identified as C. siamense and C. fructicola. The same four species identified on small fruits were also present on apple in Kentucky. Cross-inoculation assays on detached apple, blueberry, and strawberry fruits revealed that all species tested were pathogenic on all three fruits. The genome tree was compared to nine single gene sequence trees, and CHS for the C. acutatum complex and ApMat for C. gloeosporioides were identified as superior sequences for species identification. Telomere fingerprinting revealed C. fioriniae clonal lineages within three orchards on apple, blueberry, and strawberry, but did not show evidence of cross-infection. Understanding more about Colletotrichum in Kentucky orchards will help improve fruit anthracnose management practices.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2020.265

Funding Information

This work was supported by Kentucky Department of Agriculture Specialty Crops Block Grant PON2 035 1700001212 (2017-2020), and by the National Institute of Food and Agriculture Hatch Program under 1014371 (2017-2022).

Available for download on Thursday, June 03, 2021

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