ISHS Acta Horticulturae 617: Workshop on Rootstocks' Performance in Phylloxera Infested Vineyards
ASSESSING THE RISK OF PHYLLOXERA TRANSFER DURING POST-HARVEST HANDLING OF WINE GRAPES |
| Authors: | J. Deretic, K. Powell, S. Hetherington |
| Keywords: | pressing, crushing, destemming, grape juice, Daktulosphaira vitifoliae |
| Abstract:
Phylloxera Daktulosphaira vitifoliae (Fitch) was discovered in Australia in 1875 and has spread to some discrete grape-growing regions within the States of Victoria and New South Wales. Australia is unique amongst grape-growing countries in that quarantine boundaries known as Phylloxera Infested Zones (PIZ) have greatly assisted in restricting the spread of phylloxera to uninfested areas. A recent phylloxera outbreak outside a Victorian PIZ in early 2000 led to changes in the boundaries, highlighting the need for stringent and effective quarantine protocols. The presence of dispersive stages of phylloxera, particularly crawlers, within the vine canopy represents a risk of transfer of the insect on grapes and foliage during vintage operations. Assessing the risk of the post-harvest survival of phylloxera on grapes and grape products allows for the development of scientifically validated quarantine protocols. There are two stages in the development of a robust pest risk analysis of the post-harvest survival of phylloxera. The first stage is to assess phylloxera numbers in the canopy at vintage and the second is to assess phylloxera survival rates during each successive steps of wine-grape processing. Within the first stage, phylloxera populations in the canopies of four vineyard sites in North-East Victoria were measured close to harvest over two growing seasons as reported in Powell et al., 2000. Experiments were designed to estimate phylloxera risk in the following situations: (i) on harvested grapes during transport to the processing centre, (ii) during grape crushing and destemming and (iii) during grape pressing and (iv) in unclarified juice. Phylloxera survived all sampled mechanical processes including transportation, crushing/destemming, pressing and unclarified juice. This is the first published risk evidence of post-harvest phylloxera survival in Australia. | |
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