Prevalence and distribution of phony peach disease (caused by Xylella fastidiosa) in the United States

Authors: JOHNSON, KENDALL - University Of Georgia; Bock, Clive; VINSON, EDGAR - Auburn University; BRANNEN, PHILLIP - University Of Georgia

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2022
Publication Date: 2/1/2023
Citation: Johnson, K.A., Bock, C.H., Vinson, E.L., Brannen, P.M. 2023. Prevalence and distribution of phony peach disease (caused by Xylella fastidiosa) in the United States. Plant Disease. 107:326-334. https://doi.org/10.1094/PDIS-03-22-0653-RE.
DOI: https://doi.org/10.1094/PDIS-03-22-0653-RE

Interpretive Summary: Peach is an important fruit crop in the United States (U.S.). Phony peach disease (PPD), caused by a plant pathogenic bacteria (Xylella fastidiosa) has been a major cause of yield loss since it was first observed in 1885. Historically, a federal eradication program for removal of PPD trees between 1929 to 1972 maintained the disease at a manageable level. No surveys have been conducted since the program was terminated in 1972, so the current prevalence of PPD in the U.S. was unknown. We surveyed orchards in Alabama, Florida, Georgia, and South Carolina from June to August of 2020, and except for South Carolina and northern Georgia, PPD was prevalent. PPD incidence ranged from 0% to 30.5%. Additional written surveys confirmed PPD to be of significant concern in the southeastern region of the U.S., but in other states where previously reported, it is either not present or has very low prevalence when compared to historical accounts of the disease.

Technical Abstract: Peach is an important specialty fruit crop in the United States (U.S.), and phony peach disease (PPD), caused by Xylella fastidiosa (Xf) subspecies multiplex, has been a major cause of yield loss since it was first observed in 1885. Under a federal eradication program, surveys of PPD were conducted from 1929 to 1972, when the program was terminated. No surveys have been conducted in ~50 years, so the current prevalence of PPD in the U.S. was unknown, especially in the Southeast where damage was previously most severe. To ascertain the status of PPD, we surveyed orchards in Alabama, Florida, Georgia, and South Carolina from June to August of 2020, and except for South Carolina and northern Georgia, PPD was prevalent. Trees in 17 orchards were subjected to confirmation of Xf using the AmplifyRP® XRT+ for Xf to corroborate our visual assessments; based on these tests, PPD incidence in the orchards ranged from 0% to 30.5%. Ancillary written surveys relative PPD presence and prevalence were sent to fruit pathologists from universities in twenty states where PPD was historically reported. Only 36.8% of respondents reported that PPD either currently or recently occurred in their state and of these, three reported PPD to be of significant concern. The results of the physical and written surveys indicate PPD remains prevalent mainly in the southeastern region of the U.S., but in other states where previously reported, it is either not present or has very low prevalence when compared to historical accounts of the disease.