In this section:
Vine health
Improving vineyard productivity through assessment of bud fruitfulness and bud necrosis
2002-2005 Contact: Dr Belinda Rawnsley.
GWRDC final report August 2005 (LARGE PDF 7 MB)
The grapevine compound bud contains three or more buds with the primary bud producing the fruiting shoots for the following season. Primary bud necrosis (PBN) is a physiological disorder resulting in the death of the primary bud. Bud dissection used to assess bud fruitfulness and predict yield potential in vineyards has highlighted the incidence of PBN. Without bud dissection, PBN can go undetected as shoots derived from secondary buds produce fewer bunches and these are typically smaller. Consequently, yield potential is not achieved in vineyards affected by PBN. The project aims were to: assess the distribution and extent of PBN, determine timing and development of PBN and recommend appropriate management options for control. This study showed that PBN is a problem in most viticultural regions in Australia. Shiraz is the most susceptible cultivar and PBN occurred around flowering, coinciding with bud differentiation, and increased to the onset of winter. Excessive vigour contributes to high levels of PBN, and is related to the naturally produced growth hormone, gibberellic acid (GA3). Bud position, pruning levels and irrigation influence the incidence of PBN, whereby severe pruning and water stress leads to high PBN. Balanced pruning is required to (1) reduce the incidence of PBN, (2) reduce excessive vigour and (3) reach a desired yield target with satisfactory quality.
Implications of strategic irrigation management practices for vine root health
GWRDC funded, July 2003-July 2006. Contact: Dr Belinda Rawnsley
There is currently a lack of information on the effects of irrigation on long term vine root health. Management-imposed changes in soil water availability and the health of the soil ultimately affects the availability of water and nutrients through the root system, the ability of a plant to control pests and disease, and ultimately, has an impact on both yield and quality of produce.
Root growth and distribution are affected by vines under irrigation, but it is unknown if these changes increase vine susceptibility to root pathogens. Plant-pathogenic fungi in the genera Phytophthora, Rhizoctonia and Pythium, constitute a high proportion of the fungal community found in vineyards and vines under stress may have greater susceptibility to the soil-borne pathogen, Cylindrocarpon sp. and vine pathogen Phaeoacremonium sp.
The aim of this project is to determine the effect of irrigation on vine root health and if rapid changes in soil water content alter the microbial community and increase the susceptibility of vines to infection by soil and plant pathogens. Also, identification of the micro-organisms present in soil of irrigated and non-irrigated systems may give an indication of soil response to irrigation and thus may influence recommendations on best management irrigation practices. This knowledge will enable grapegrowers to make informative decisions on modifying their management strategies to improve water use efficiency and assist in the understanding of the implications of irrigation on long term vine health.
