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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #400510
Research Project: Development of New Stone Fruit Cultivars and Rootstocks for the Southeastern United States

Location: Fruit and Tree Nut Research

Title: Plant growth stimulants and defense activators fail to control phony peach disease in mature peach orchards

Author
item JOHNSON, KENDALL - University Of Georgia
item Chen, Chunxian
item Bock, Clive
item BRANNEN, PHILLIP - University Of Georgia

Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/11/2023
Publication Date: 5/12/2023
Citation: Johnson, K.A., Chen, C., Bock, C.H., Brannen, P.M. 2023. Plant growth stimulants and defense activators fail to control phony peach disease in mature peach orchards. Crop Protection. 171/106282. https://doi.org/10.1016/j.cropro.2023.106282.
DOI: https://doi.org/10.1016/j.cropro.2023.106282

Interpretive Summary: Xylella fastidiosa subspecies multiplex is a plant pathogenic bacterium that causes phony peach disease (PPD), a serious disease of peach in the southeastern United States. The current management strategy for PPD is removal of diseased trees. Novel plant growth stimulants and plant defense activators have not been tested to explore whether they can reverse PPD. Thus, trials were conducted in peach orchards in 2021 and 2022 with treatments applied as foliar or root drench applications. Treatments were Rio, ProGibb 40SG, Maximizer, Actigard 50WG, and K-phite7LP. Only ProGibb 40SG increased shoot growth, but no treatment affected bacterial populations in the trees, meaning all trees remained diseased. None of the treatments showed promise to control PPD in diseases peach trees.

Technical Abstract: The bacterium, Xylella fastidiosa subspecies multiplex, causes phony peach disease (PPD), a serious disease of peach in the southeastern United States. The current management strategy for PPD is removal of symptomatic trees, but other management options should be explored. Field efficacy trials with plant growth stimulants and plant defense activators were conducted in orchards of ‘Julyprince’ in 2021 and 2022, and ‘Springprince’ in 2021. Treatments were applied either as a foliar or root drench application once a month for three consecutive months during the growing season. Treatments included Rio, ProGibb 40SG, Maximizer, Actigard 50WG, and K-phite'7LP. In 2021, ProGibb 40SG provided increased shoot growth in both varieties, but cycle threshold (Ct) values did not suggest that any treatment affected bacterial titer. In 2022, applications were initiated one month later and no significant effects on shoot growth parameters or bacterial titer were observed among treatments.