Abstract
Extreme winter temperatures during the 2018–2019 dormant season contributed to trunk collapse and complete trunk death of numerous genotypes throughout a diverse grapevine planting in eastern North Dakota, USA. Through the early portion of the dormant season, 12 genotypes were screened to identify lethal temperature exotherms of primary buds; from these results, none were anticipated to be fully prepared to survive the −37 °C minimum temperature recorded in the region. Trunk collapse, death, and survival were monitored for 35 replicated genotypes. New trunks were retrained from suckers and monitored for growth following trunk removal. Only five genotypes exceeded 50% trunk survival at the end of the 2019 growing season, ‘Valiant’, ‘King of the North’, ‘John Viola’, ‘Baltica’, and ‘Bluebell’. Following re-establishment, ‘La Crescent’ was the most vigorous genotype with the largest sucker circumference, sucker length, and internode length. Nearly all genotypes evaluated produced suckers with lengths approaching the high-wire trellis height (1.8 m), designating their potential for cordon retraining in 2020. Cumulatively, however, the lethal temperature exotherm results and the trunk survival examination indicate a harrowing need for investigation of new management practices (such as protected training systems) and the generation of new cold-hardy genotypes to enhance productivity under standard unprotected systems.
Highlights
Low winter temperatures are one of the most critical environmental factors limiting productivity of grapevines in the Eastern United States [1,2,3]
Statistical analyses of sucker re-establishment metrics were conducted for replicate plots as a mixed-model analysis of variance (ANOVA) with genotype defined as a fixed effect and replicate defined as a random effect using JMP Pro 14.0.0 (SAS, Cary, NC)
“Valiant” consistently performed as the most cold-injury-resistant according to LTE50 values for primary buds
Summary
Low winter temperatures are one of the most critical environmental factors limiting productivity of grapevines in the Eastern United States [1,2,3]. Even cold-hardy interspecific hybrid grapevines with diverse genomic contributions from V. riparia may be susceptible to injury under the most dire of Eastern US continental winter events [8,9]. Dead trunks of own-rooted vines require renewal with new shoots, typically suckers, arising at or just below the soil level [10,11] This is a gradual process, requiring time for the grapevines and vineyards to re-achieve mature production capacity. Burying of the vines under soil to prevent winter damage is a common application in many locations across the world [5,11,13,14] North Dakota grapevine production consists of cold-hardy interspecific hybrid grapevines, typically with a focus on wine grapes [9]. Goals included the identification of genotypes with potential to perform well for local farmers or for use as parents in regional grapevine breeding efforts
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