Project number
P04000235
Project leader
Halleen, F
Institution
ARC Infruitec-Nietvoorbij, Stellenbosch
Start date
2019
EXECUTIVE SUMMARY
Objectives and Rationale
To manage and plan for the replacement of rootstock mother blocks by determining, in parallel, the incidence of trunk disease pathogens, physiological status, and morphological dimensions of rootstock canes from mother blocks of various ages.
Methods
Conduct a survey in 41 mother blocks to determine morphological dimensions, physiological status and fungal pathogen status of one-year-old canes over three seasons. Conduct a survey of vine heads in 38 mother blocks over two seasons for the incidence of trunk pathogens. Determine the effect of infection on callusing and nursery vine performance.
Key Results
One-year-old canes serve as an inoculum source in newly grafted vines. Botryosphaeriaceae infection in the rootstock mother blocks results in infected 1-year-old canes. The morphological and physiological data from the one-year-old canes were influenced by season, and not by rootstock mother vine age. Significant correlations were recorded between several minerals and between minerals and cane morphology. Younger rootstock mother blocks were shown to produce more usable canes than older mother blocks. The main occurring grapevine trunk disease pathogen in rootstock mother vine heads is Phaeomoniella chlamydospora (Petri disease), followed by Botryosphaeriaceae spp. (Bot canker and dieback), Hymenochaetaceae spp. (Esca), Togniniaceae spp. (Petri disease), Diaporthales spp. (Phomopis dieback) and Diatrypaceae spp. (Tandpyn-like). High incidences of GTD pathogens were recorded in the heads of all rootstock mother vines, mostly irrespective of age. Vine age does not have a direct impact on the total certifiable yield or root mass of nursery vines. However, inoculum in contaminated canes originating from infected rootstock mother blocks has been shown to adversely affect nursery vine performance. The nursery process has been shown as the only source of Pleurostoma richardsiae inoculum in this study, which needs to be addressed.
Key Conclusion of Discussion
This study, for the first time, provided an opportunity to combine physical, physiological and GTD details on the same rootstock mother material and to provide answers that are hitherto unknown. The fungal pathogens identified from the heads and canes of mother vines are important grapevine trunk disease pathogens that can cause problems during the propagation process or in newly established vineyards. It affects the ability of the rootstock mother vines to produce healthy canes and reduces the productive lifespan of mother blocks.
Take Home Message for Industry
Grapevine trunk diseases need to be managed more effectively in rootstock mother blocks, and planning for the replacement of these blocks needs to be done at a younger age. Aerial inoculum from within rootstock mother blocks should be contained by means of sanitation. This entails the removal and destruction of any dead plants or plant material, the removal of fungal fruiting bodies, the control of insect vectors and the regular sanitation of pruning shears during the pruning process. The use of pruning wound protectors is urged to be used by the South African grapevine industry immediately after pruning of rootstock mother blocks. Whether painting or spraying, it is crucial to ensure comprehensive coverage of all wounds, including those on one-year-old wood, regardless of their size. Another strategy to combat the infection of one-year-old canes in rootstock mother blocks is to trellis rootstock mother vines.
Van Jaarsveld et al 2025 Adverse effects of grapevine trunk diseases