Timing of harvest is largely determined by the fruit’s appearance, flavour, texture and sugar-acid ratio. Table grapes are harvested when they are ready to be consumed as they do not ripen after they have been picked (Rosenstock 2007). To determine the appropriate time to harvest, growers monitor the percentage colouration in the clusters and quantify soluble solid levels in a random selection of berries (Rosenstock 2007). In California, a soluble solids concentration of 14 to 17.5 per cent is normally used to identify fruit which are ready for harvest (Crisosto and Smilanick 2004). A minimum colour requirement is also applied to red and black table grape varieties to ensure adequate colour in the cluster prior to harvest (Crisosto and Smilanick 2004).
The majority of Californian table grapes are packed in the field, with few being shed packed (Crisosto and Smilanick 2004). Field packed grapes are commonly picked and placed into a picking container (Crisosto and Smilanick 2004). The cluster is trimmed to remove any defective fruit, including sunburnt, decayed, undersized, cracked or irregular-shaped berries (Rosenstock 2007). Defective clusters are either completely discarded or included in low grade category (Rosenstock 2007). Defective clusters may be too compact to examine the interior, filled with shot berries, too small, have an excess of defective berries, or have inadequate colouring (Rosenstock 2007). The picking container is then moved to a packer working in a portable stand in the avenue between vineyard blocks (Crisosto and Smilanick 2004). Packed containers are subject to quality inspection and weight checking (Crisosto and Smilanick 2004). The packer places the grape bunches into boxes. After packing, grapes are arranged onto pallets and sent to packing sheds and/or treatment facilities.
1.10Post-harvest
After harvest, fruit is pre-cooled to remove field head, reduce respiration, slow growth of decay, and to minimise water loss (Rosenstock 2007). Pre-cooling commences as soon as possible. Once the grapes have been pre-cooled, pallets are placed in a storage room until transportation occurs (Crisosto and Smilanick 2004). Under current export conditions, table grapes destined for the Australian market are fumigated with a combination sulfur dioxide (SO2) and carbon dioxide (CO2) treatment before they are cooled. This is because the fumigation treatment must occur at 15.6°C (60°F) or greater. After fumigation the table grapes are then cooled to undergo at least 6 continuous days of cold treatment at a pulp temperature of –0.50°C ± 0.50°C. After cold treatment they may then be moved into storage until they are transported for export.
Optimum refrigeration conditions for table grapes in storage are between -1 and 0 °C with relative humidity levels of 90 to 95 percent (Crisosto and Smilanick 2004). It is recommended that the pulp temperature of the berries should range from -0.5 to 0 oC during post-harvest storage (Crisosto and Smilanick 2004).
Optimum storage conditions for table grapes in transit range from -1 to -0.5 oC with relative humidity of 90-95% (Welby and McGregor 2004). Under these conditions, grapes may have an approximate storage life of 2-6 months (Welby and McGregor 2004). Figure 7 summarises the post-harvest packing house, storage and distribution steps for Californian table grapes. Table grapes destined for export to Australia are subject to the conditions detailed in Chapter 1.24.2.
Figure 7 – Summary of vineyard and post-harvest packing house, storage and distribution steps for Californian table grapes
Commercial production and export information 1.10.1Production statistics
California is the largest producer of table grapes in the USA. The majority of Californian table grapes are produced in the San Joaquin Valley, with most production occurring in Kern, Tulare and Fresno counties (USDA 2010a). In 2011, Kern had approximately 15,500 ha of bearing and non-bearing vines, Tulare had over 10,000 ha and Fresno had approximately 5,000 ha (CDFA 2012a). Riverside County has the largest table grape plantings outside the San Joaquin Valley, with approximately 2,800 ha of bearing and non-bearing vines (CDFA 2012a).
In 2010, California had over 34,000 bearing hectares of table grape vines. The California Department of Food and Agriculture (CDFA 2012a) reported production of over 900,000 tonnes of grapes with a value of US$385.6 million (Table 3 .8). Whilst production of table grapes in California steadily increased between 2006 and 2010, the prices for fresh grapes declined contributing to a lower value of production compared to previous years (Table 3 .8).
Table 3.8 – Production statistics for table grapes in California from 2000 to 2010
Year
|
Production (tonnes)
|
Value of production (US$M)
|
2000
|
702,161
|
437.4
|
2001
|
646,823
|
435.2
|
2002
|
674,038
|
457.6
|
2003
|
664,059
|
407.6
|
2004
|
698,532
|
535.0
|
2005
|
791,065
|
385.1
|
2006
|
650,452
|
643.8
|
2007
|
717,583
|
622.9
|
2008
|
882,691
|
394.5
|
2009
|
792,880
|
406.0
|
2010
|
914,442
|
385.6
|
Source: California Department of Food and Agriculture (CDFA 2012a)
Export statistics
The USA is the second largest exporter of table grapes in the world after Chile (USDA 2010a). California is the top export state, followed by New Jersey, New York and Pennsylvania (USDA 2010a). Approximately 35 per cent of the USA’s table grape crop is exported (USDA 2011). In 2009, the United States Department of Agriculture reported that the USA exported 303,000 tonnes of table grapes valued at US$586 million to 86 countries (USDA 2010a). Canada was the largest importer, taking 33 per cent of the crop, followed by Hong Kong (11 per cent) and Australia (8 per cent) (Table 3 .9;(USDA 2010a). Other major export markets include the Philippines, Indonesia, Taiwan, Mexico, the United Kingdom, Malaysia, New Zealand, Thailand and Vietnam (USDA 2010a). Table 3 .9 summarises table grape exports from the USA to its main markets for selected years over the period 2005 to 2009 as reported by the United States Department of Agriculture (2010a).
Table 3.9 – Fresh table grape exports from the USA to major markets 2005 to 2009 (US$ millions)
|
(US$ millions)
|
% share
|
Country
|
2005
|
2006
|
2007
|
2008
|
2009
|
2009
|
Canada
|
158
|
150
|
185
|
169
|
194
|
33%
|
Hong Kong
|
44
|
43
|
45
|
59
|
63
|
11%
|
Australia
|
16
|
16
|
34
|
47
|
48
|
8%
|
Philippines
|
11
|
12
|
15
|
18
|
24
|
4%
|
Indonesia
|
15
|
11
|
17
|
26
|
24
|
4%
|
Taiwan
|
26
|
17
|
20
|
24
|
21
|
4%
|
Mexico
|
51
|
49
|
51
|
60
|
19
|
3%
|
United Kingdom
|
13
|
12
|
17
|
23
|
19
|
3%
|
Malaysia
|
63
|
40
|
20
|
16
|
15
|
3%
|
New Zealand
|
8
|
8
|
13
|
13
|
14
|
2%
|
Thailand
|
10
|
10
|
12
|
15
|
13
|
2%
|
Vietnam
|
5
|
5
|
7
|
9
|
12
|
2%
|
Other
|
120
|
124
|
116
|
130
|
120
|
20%
|
Total
|
540
|
497
|
552
|
609
|
586
|
100%
|
Source: United States Department of Agriculture (2010a)
Volume of trade to Australia and Western Australia
Californian table grapes have been imported into Australia, excluding Western Australia, since 2002. Export volumes have increased since that time; however they have somewhat stabilised after 2007, although there are still year-to-year fluctuations (Table 3 .10). This data has been used to estimate possible trade volumes to Western Australia for consideration in the pest risk assessment in Chapter 4.
In 2012, based on the resident population at the June quarter, the population of Western Australia was around 12 per cent of the combined population of the other states and territories of Australia (2,430,300 and 20,253,300 respectively) (ABS 2012). If trade volumes to the other states and territories could be expected to fluctuate around 11,500 tonnes per year, based on trade volumes since 2007, then it is assumed that the volume exported to Western Australia could be about 1,400 tonnes per year (12% of 11,500 tonnes).
Table 3.10 – Imports of Californian table grapes to Australia (excluding Western Australia)
Year
|
Volume (tonnes)
|
2002
|
921
|
2003
|
1043
|
2004
|
3909
|
2005
|
4198
|
2006
|
4314
|
2007
|
10889
|
2008
|
14787
|
2009
|
15898
|
2010
|
5762
|
2011
|
10571
|
Source: (TradeMap Australia 2011)
Export and harvest season
In California, the table grape season begins around May with the earliest varieties being Perlette, Flame Seedless and Sugraone. Flame Seedless has a very long season in California usually lasting until around December, whereas Perlette and Flame Seedless varieties last only until August (Pollack and Perez 2007). Thomson Seedless also has a long season in California starting in June and ending in January (Pollack and Perez 2007). Red Globe is available from July through January, and Ruby Seedless and Crimson Seedless from August through January. Calmeria is available only from September, but lasts through to January of the following year (Pollack and Perez 2007).
Since exports of fresh table grapes from California to Australia began in 2002, the export season to Australia has been from June to November (with one exceptional year where consignments were also shipped in December).
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