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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #367965
Research Project: Development of New Stone Fruit Cultivars and Rootstocks for the Southeastern United States

Location: Fruit and Tree Nut Research

Title: Effect of a late spring application of hydrogen cyanamide on high-chill peaches

Author
item Chen, Chunxian
item Beckman, Thomas

Submitted to: Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2019
Publication Date: 11/8/2019
Citation: Chen, C., Beckman, T.G. 2019. Effect of a late spring application of hydrogen cyanamide on high-chill peaches. Agronomy. 9(11):726-736. https://doi.org/10.3390/agronomy9110726 .
DOI: https://doi.org/10.3390/agronomy9110726

Interpretive Summary: Peach trees require enough chill hours below 7.2' or 45' in the winter to mature buds and lead to normal budbreak in the coming spring. Some high-chill peach cultivars receiving inadequate chill hours (some less than half of the chilling requirement) in Georgia in 2016-2017 displayed almost no budbreak by mid-April 2017. In this study, we used nine of these peach cultivars to study the effect of a late spray application (April 13th) of Dormex (hydrogen cyanamide is the active component) on budbreak, on the year-end vegetative growth, and on the following year yield. The spray was also a deliberate attempt to save these dead-looking trees. The data collected in this study showed a late Dormex spray application stimulated earlier lateral budbreak and also caused some level of phototoxicity to all types of buds and new growth, but had little impact on flower budbreak, fruit set, the overall year-end vegetative growth, or the following year yield.

Technical Abstract: Due to a record low chilling accumulation in the winter of 2016-2017, many high-chill peach cultivars displayed almost no budbreak by mid-April of 2017 in central Georgia, the United States, where budbreak usually occurs around mid-March. In this study, nine of these peach cultivars were used to study the effect of a late Dormex spray application (April 13, 2017) on subsequent budbreak, year-end cumulative vegetative growth, and following-season yield. Dormex was found to have strong stimulating effects on lateral budbreak but little effect on terminal and floral budbreak. It also had obvious phytotoxic effects on lateral, terminal and floral buds and growth. The effects varied among genotypes, tree ages, and shoot types. The peak of the effects occurred two weeks post-application. Most floral buds abscised before they swelled. Between Dormex-sprayed trees and unsprayed controls, there was no significant difference in the number and average length of the new lateral shoots at the end of 2017, and in the number and weight of the fruit harvested in 2018. In conclusion, our data showed a late Dormex spray application stimulated earlier lateral budbreak and caused some level of phototoxicity to all types of buds and new growth, but had little impact on flower budbreak, fruit set, year-end vegetative growth, or following-season yield.