Sustainable Vineyard Systems
The Australian wine, dried grape and table grape industries must accelerate the adoption of environmentally sustainable policies and practices in all aspects of the industry.
International pressures for environmental responsibility are increasing, and enhancement of Australia's established 'clean and green' image will be a vital component for future market growth. Environmental sustainability will help provide a secure production future for the viticultural industries, guarantee current investment trends and attract significant consumer support.
This program addresses the combined aspects of economic and environmental sustainability through an improved understanding of the interaction between the grapevine and its soil water environment.
Research projects will address the need to better manage scarce water resources to achieve increased grape quality and provide improved ways to manage vineyards with saline soils and/or watertables.
It will also address threats to grapevine longevity, with an emphasis on trunk diseases, in particular those caused by Botryosphaeria, Phaeoacremonium and Eutypa. Other research will be conducted into finding better ways to manage limited water resources including the investigation of strategic irrigation technologies, controlling major soil-borne pests such as nematodes and phylloxera, protecting the biodiversity of vineyards and minimising the application of chemicals.
Trial sites in key regions will focus on the major sustainability issues of the grapevine - soil - water interaction and its relationship to vine performance, particularly yield and quality, and will provide a means of facilitating technology transfer.
Program Manager
Dr Robert Walker
Dr Robert Walker, PhD, BagrSc (Hons) (Tasmania) is Program Leader (Horticultural Management Systems) with the Horticulture Unit of CSIRO Plant Industry in Merbein, Victoria. He has had extensive experience in senior research leadership and management including appointments as Assistant Chief and Chief (Acting) of the CSIRO Division on Horticulture. In 1996 he was seconded to Woolworths Ltd, National Produce, NSW.
program update (19/12/2005)
Producing quality grapes in a sustainable manner, taking into account commercial and environmental considerations as well as issues such as water limitations and the threat of pests and diseases is an ongoing challenge.
The complex interactions between vines and production inputs is at the core of developing sustainable production systems for our industry.
How much can water application be reduced before there are issues with salinity? What will be the implications for yield and quality? Are these results the same if the canopy management system is changed? Are there differences between each variety?
These are the kinds of questions that are being asked within this research program and in the past year we have continued to provide answers for the industry. With many projects now completed, we have been able to share our results with industry, particularly focusing on the region’s where the projects have been undertaken. Workshops, presentations and papers have also been broadly distributed to share the results, and complete project reports are available on the CRCV website for anyone interested in the technical details of the completed projects.
Limited water resources
The use of our limited water resource continues to be a dominant industry issue and major focus of our research. Our work into monitoring vine water stress through a plant-based sensor has progressed and we have shown there is a correlation between leaf water potential and cavitation events over both diurnal and drying cycles in Chardonnay and Grenache. Results have shown consistent differences in the trend of cavitation in the two varieties. In Chardonnay the onset of cavitation occurs first in the petiole and later in the stem (at more negative water potential) before developing into ‘runaway’ cavitation under severe stress. Grenache evidently has some mechanism to delay onset of ‘runaway’ cavitation, compared with Chardonnay.
In the past year we have taken more than 1400 soil core samples to assess the impact of deficit irrigation technologies on soil health and structure. In vineyards where irrigation systems have been charged e.g. from full ground cover to drip, we have seen that root distribution adjusts to the current irrigation practice and that existing non-irrigated roots (e.g in the mid-row) are maintained. The initial results have also shown that drip irrigation increases root volume and that within a single vine, water can move from roots in wet soils to roots in dry soil.
At Langhorne Creek we are working with Orlando Wyndham to grow Cabernet Sauvignon to pre-defined quality specifications determined by the winery and within total water limitations. We are using a range of irrigation and surface management techniques, in combination with surface mulch. We’ve seen that mulch treatments have given higher yield compared to non-mulch treatments due to an increase in bunch number per vine and berries per bunch. The project has highlighted, that event with close monitoring, it is very challenging to meet grape quality specification from season to season.
Our project looking at grapevine root hydraulics has been taking a closer look at soil drying and wetting cycles and the roles that grapevine aquaporins play. We have found that aquaporins appear to be important to the overall hydraulic conductivity of grapevine roots. Not surprisingly we have seen that water stress causes significant reductions in hydraulic conductivity and that the recovery time might be influenced by changes in anatomy and the size of the root system.
Managing trunk disease
In the past year our work into nursery management strategies to prevent the dispersal of Phaeomoniella chlamydospora (Pch) in infected propagation material has continued. Our work has focused heavily on hot water treatment of dormant vine cuttings and we have developed a series of nursery management strategies to prevent the spread of Pch and ensure the best outcomes for hot water treatment. These strategies have been delivered to industry through ‘Making every stick count’ workshops.
Eutypa dieback is another disease we are focusing our efforts on and the team has made excellent progress with greenhouse experiments. Inoculation of the disease in this environment has previously been problematic, with symptoms often not expressed for a couple of years. We have now managed to observe symptoms within eight months of inoculation. Our findings show that Grenache is the most susceptible variety to this disease and that different Eutypa isolates (strains of the disease) differ in their ability to induce foliar symptoms. We believe one particular compound called Eutypinol, which is found in 29 of 30 isolates, could be a promising marker for the development of a test to detect Eutypa and we have two novel compounds under evaluation.
Our phylloxera project is assessing the use of specto-optical and chemical fingerprinting for the early detection of this vineyard pest. Vines infected with phylloxera exhibit spectral characteristics associated with general plant stress. During the growing season we compared the spectra of uninfested and infested Cabernet Sauvignon and found significant differences, with the clearest differences exhibited in January.
Integrated Viticulture
One of the major aims of this program is to look closely at the complex relationships between vineyard management practices and their effects on vine performance. Although we can learn a lot from a research perspective by looking at irrigation, for example, in isolation, this is not the commercial reality and we also need to assess integrated viticultural management strategies.
We have been investigating the relationship between irrigation and nitrogen management on grapevine vigour and the role of root derived cytokinins. A field trial in Griffith has found no differences in vine performance with timing of different nitrogen application treatments but significant differences in vine performance with irrigation treatments. What we have seen so far is that there are no interactive effects between irrigation and nitrogen.
Cover crops can confer many benefits in the vineyard and we have been looking at how they influence soil structure and vine nutrition. A range of cover crops have been planted including triticale, fodder raddish, sabo medic and annual ryegrass. We are interested in each species’ ability to penetrate strong soils, the soil moisture content, root distribution, water infiltration and microbial activity. This trial will be expanded in 2005/06 with nine species to be examined.
Related to our irrigation work, we have a project focused on the impact of irrigation on soil water availability and root growth. Marked differences exist between irrigated and non-irrigated sites in terms of surface soil physical properties, but few differences at sub-soil level. At our McLaren Vale field site we have found a trend of improved soil physical properties along the vine row away from the drippers, suggesting drip irrigation is adversely altering soil structure despite gypsum application.
The issue of soil salinity is of huge importance, particularly in relation to reduced irrigation schedules. One of the areas we are interested in is the ability of rootstocks to exclude salt. Our field work has indicated that the deterioration in chloride exclusion ability of Ramsey, 1103 Paulsen and 110-14 is site specific and apparently related to poor drainage. However, the rootstock 140 Ruggeri exhibits more sustainable chloride exclusion and a superior physiological response to combined waterlogging and salinity.
One of our newer and most ambitious projects is assessing water, nitrogen and phosphate losses from vineyard systems under different irrigation and nutrition strategies in the major wine grape growing regions of southern Australia. We have been collecting hourly soil water content data from two sites and will have a third site ready for the 05/06 season. During the next season we will also have drainage meters installed to provide additional information.
Shiraz berry shrivel has been a problem for some growers and in response we have a project to find out why this can occur. Measurements of hydraulic conductance have shown a ten-fold reduction in whole berries from veraison to ripeness. Backflow may be an important component of berry weight loss in Shiraz, particularly if the phloem ceases functioning at high osmotic potentials near maximum weight.
Managing seasonal variation in winegrape maturation has been the focus of another of our projects. We have applied three irrigation treatments to Cabernet Sauvignon and have seen water stress effects on the canopy resulting in smaller berries which had reduced skin and flesh fresh weight but similar skin and flesh dry weight, suggesting a lower berry water content. Seasonal variation has greater effects on physiology and berry ripening processes compared with deficit irrigation treatments.
A great success of this program has been the enormous amount of information we have about vineyard management. We have used this information in a wide range of software applications that are now being used extensively by industry. The PAM-AusVit management program is being used by a wide range of companies in Australia and is being trialled in New Zealand. This year we have released a spray diary product called QA Link and Australian Viticultural Investigator, a pest management and disease program. We have also updated the AusVit chemical database, released VERA version 2 for environmental assessment and are in the process of finalising VineLOGIC version 2 for use in education and training environments.
Biodiversity
Biodiversity is important to the health of the vineyard and the surrounding environment, but measuring it is not something we have previously attempted. Our research is finding out which species are beneficial in the vineyard for practical considerations such as pest control and improving soil health.
We have found that higher numbers of spiders, beetles, lacewings, and flies are likely to have a positive influence on pest control and earthworms improve soil condition. Straw as a ground cover encouraged relatively larger populations of generalist predators (spiders, beetles, lacewings and flies) and parasitoids (wasps and flies) as well as earthworms. The reduction in water associated with PRD irrigation however reduced the number of spiders, beetles and earthworms.
Another element of our work into biodiversity is looking at the effects of agrichemicals on the environment. We are especially looking at spray drift, drainage water and leeching and copper accumulation in vineyard soils.
