How to improve the success of dead vine replacement: insights into the impacts of young plant‘s environment 

Abstract

Context and purpose of the study – Grapevine faces multiple biotic and/or abiotic stresses, which are interrelated. Depending on their incidence, they can have a negative impact on the development and production of the plant, but also on its longevity, leading to vine dieback. One of the consequences of vine dieback on production is the increased replacement rate of dead or missing vines within a parcel. Replacements can be very costly and time consuming for the vinegrower, especially because success (i.e. defined by the survival and growth of the young vine planted in place of the dead plant) is not guaranteed every year. Factors influencing the success of this replacement can be grouped into two main categories: the plant environment and the vinegrower practices. The aim of this study was to quantify plant mortality after such a replacement in different vineyards over several years, and the influence of the plant’s environment on this mortality

Material and methods – For four years, plants replacements were carried out in production vineyards. A set of 83 batches distributed in 44 parcels corresponding to more than 7500 replacement plants were monitored. The year and density of planting, rootstock, and  variety as well as soil type and maintenance were recorded for each parcel. Plant survival was monitored twice a year.

Results – As the plants were coming into production, the average survival rate was 83% of the initial batches of plantings. However, survival rates varied greatly depending on plot characteristics. Multi-year monitoring of plant survival showed that 60% of mortality occurred within the year following plant replacement. Over the study period, the average first-year mortality rate of replaced plants ranged from 7.4 to 17.1%, highlighting a vintage effect. In the second and third years after replacement, mortality was found to be higher in late winter than during the growing season. Thus, one hypotheses proposed is that the reserve status of the plant material may be more critical to the survival of these plants than the impacts of tillage or lack of water during the growing season. Nevertheless, mortality during growing season accounted for one-third of total mortality in a given year, which could potentially be reduced through better care of the young plants. Statistical analyses revealed no variety effect of and no date of the first plantation effect of the initial parcel while a significant soil effect was detected. This experimental monitoring should make it possible to provide answers on the impact of the environment of the replacement plant on its survival over time, its development and its production. These results highlight perspectives to improve the survival of replacement plants in vineyards.