New Winetech projects for 2017 (Part 2)

by | May 1, 2017 | Winetech Technical, Oenology research, Viticulture research

1. Ecology and management of Lobesia vanillana in vineyards

Researcher: Pia Addison

Lobesia vanillana is a pest species that was recently confirmed to attack wine grapes in the Western Cape. Grapes have not been listed as a host for this pest, therefore its ecology in vineyards is a mystery. Preliminary observations have indicated that this could be a severe, direct pest that appears to be expanding its host and geographic range. Apart from taxonomic literature and one host list, excluding samples from the Western Cape, no information is available for L. vanillana. The aim of this study is therefore to obtain data on the basic ecology and possible management of this pest. The following questions will also be addressed:

  • What are the best trapping systems to use for monitoring this pest?
  • What is its current distribution in vineyards and what are its hosts?
  • What management practice could be applied to control its populations?

Research will focus on biological control to assist in developing an initial management strategy.


2. Pruning wound protection of rootstock mother vines

Researcher: Francois Halleen

Research has indicated that protection of pruning wounds on rootstock mother vines should be a priority, considering the availability of inoculum and high pathogen spore counts within rootstock mother blocks. Although pruning wound protection has been studied in South Africa, no study has investigated pruning wound protection in rootstock mother vines.

The aim of this study will be to determine the duration of pruning wound susceptibility of rootstock mother vines. Furthermore, various chemical and biological control agents will be selected and evaluated to determine their efficacy to protect pruning wounds.

Knowledge gained from this study will be used to formulate a protocol based on scientific evidence. The protocol will provide guidelines for local grapevine nurseries, rootstock mother block owners and the Plant Improvement Scheme on effective pruning wound protection of rootstock mother vines. This will benefit the industry by helping to manage pruning wound infections and to minimise the risks of spreading trunk pathogens in vineyards through infected propagation material.


3. Investigating the effect of sparging on white wine

Researcher: Wessel du Toit

Sparging is used as a tool to reduce dissolved oxygen concentration in wines before bottling. Either nitrogen gas or carbon dioxide gas can be used to sparge a wine. This treatment is thought to protect the wine from oxidation. A loss of aroma due to the volatility of aroma compounds during sparging have been reported, however, this has not been conclusively proven. The question is whether sparging is more beneficial for the wine sensory and chemical properties, compared to a wine that was not sparged and thus bottled with residual dissolved oxygen concentrations. Other than that, the choice of gas used can also potentially influence the profiles and needs to be investigated. There are, however, very little information available regarding the effect of sparging on the wine’s chemical and sensory composition. Literature on the subject is limited and only popular articles can be found on the subject, none of which have done actual tests to investigate the effect of sparging treatments. The aim of this project is to investigate the effect of sparging on the chemical and sensory composition of white wines.


4. Consumers and industry experts’ perspectives on South African Chenin blanc

Researcher: Hélène Nieuwoudt

Despite market research showing a consistent increase in the annual volumes of South African Chenin blanc wine produced and sold (Sawis, 2015), there are several indicators from retail and from preliminary research, which suggest that the awareness, liking and consumption of Chenin blanc table wines by SA consumers are still lagging behind other major white wine cultivars. An important aspect emerging from previous Chenin blanc research is the consumer risk perception amongst prospective Chenin blanc consumers. To address this problem, researchers have consulted industry role players in 2016 to obtain their inputs in the current proposal, which has as main objectives: (i) an investigation into how ordinary wine consumers and industry experts perceive Chenin blanc, and; (ii) what the implications of these perceptions are for the effective marketing of Chenin.

The aim of this project is therefore to obtain cross-cultural consumers perceptions of Chenin blanc wine: ordinary wine consumers (black, white and coloured); and technical experts, i.e. sommeliers, wine judges and retail experts of the different cultural groups in order to aid marketing and communication efforts with regard to Chenin blanc. It is not to get current Sauvignon blanc and Chardonnay wine consumers to switch to Chenin blanc, but rather to support SA Chenin blanc finding its rightful place.


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