Figure 1: “Parrot beak” can occur on WA 2 fruit grown on one-year-old wood.
Washington State University’s new apple variety WA 2 is in its fifth season of intensive industry evaluation (Phase 3). On four climatically different sites, 50 to 150 trees are planted 3 by 10 feet apart, usually on Malling 9 337. Horticultural and storage performance are evaluated, while the remaining fruit is used for packing-line tests, industry sampling, and market testing.
We expect enough fruit in 2011 to provide gift boxes of fruit to packers and nurseries.
The following traits have been observed during Phase 3 evaluation:
- WA 2 has a compact growth habit similar to that of Ambrosia or semispur Red Delicious. It is sensitive to replant disorder, and requires fumigation and aggressive strategies to grow the tree, fill the space, and then produce fruit. In virgin ground, WA 2 fills the 3- by 10-foot spacing in the third growing season. On weaker, replant ground, WA 2 has not adequately filled its space. In these conditions, a 24- to 30-inch in-row spacing might be the best way to fill the canopy volume. Malling 9 rootstocks will grow more fruit more consistently and have better fruit size than semidwarf rootstocks.
- Fruit sets evenly and in singles, which facilitates annual cropping. Fruit size is a little larger than Gala, peaking on size 80 to 100. WA 2 likes to set on one-year wood, but this fruit is small and often russeted. In addition, the stem is often misaligned and grows across the fruit core at a 90-degree angle—a phenomenon known as “parrot beak”(Figure 1). Because of these problems, all fruit on one-year wood should be removed on second-, third-, and fourth-leaf trees. Parrot beak and russet diminish as the trees age. The original tree produced several seasons of high-packout fruit until it was removed at over ten years of age.
- WA 2 does not show high susceptibility to mildew, sunburn, or bitter pit. Mildew will show on a few terminals in a wet spring with no chemical controls applied. Stem bowl russet is common, and frost-induced russet in and over the stem bowl can occur.
- Harvest corresponds to Red Delicious timing. The fruit changes maturity slowly. Dark-colored fruit is sensitive to stem and calyx cracking. Harvest at pink-red color is the best mitigation for cracking. In 2009, an early October freeze induced a significant amount of stem-end splitting. In seasons with a mild fall, up to four harvests could maximize packouts for size and color.
WA 2 is a Red Delicious harvest season variety that has a very long storage and shelf life. It benefits from several picks at harvest and should remain in storage to mature prior to marketing. It stores well and handles a standard packing line well.
In 2010, the fruit was color picked at each of four picking dates and drenched to reduce decay. Thereafter, half of each batch was treated with 1-MCP within one week of harvest. The fruit was divided further into two and four months of regular atmosphere storage (at 33°F) and four and eight months of controlled atmosphere storage (1% carbon dioxide and 2% oxygen at 33°F). Following each storage time, fruit was removed from cold storage and held at room temperature for one week prior to evaluation.
We evaluated fruit that was subjected to a standard waxing and packing scenario, with and without presizing. After each run, fruit was placed back into cold storage for two to three weeks, and final evaluations were performed after one week at room temperature to mimic shipping and store display. Performance criteria include the appearance of the wax, number of punctures, and incidence of lenticel breakdown.
The postharvest highlights for WA 2 are:
- Fruit color is an attractive bright red-pink with distinct lenticels. The appearance of the variety improves from attractive at harvest to alluring by April.
- Fruit has excellent firmness, even after eight months in CA storage (Table 1). Low ethylene emission rates impart slow maturity changes at harvest and a long postharvest shelf life. Examples are:—Retained firmness (no more than a 0.5 pound loss in firmness after eight months in CA)
—Maximum soluble solids concentration after eight months of storage in CA
—Slow titratable acidity loss
—Little difference between MCP (1-methylcyclopropene) and non-MCP treated fruit after long-term CA storage
- No problems with disorders.
- Fruit tends to be starchy with little flavor at harvest. It is seldom well received until it has been stored for three months in regular storage or four months in CA.
- Fruit is very crisp (more so than Braeburn and Gala).
- No issues were apparent when submitted to presizing and/or packing on a commercial packing line.
- Fruit is easily cleaned and has a nice shine after waxing (Figure 2)
See also “WSU apple breeding program’s fruit evaluation system,” published in the July 2011 issue of Good Fruit Grower and “Apple selections evaluated for postharvest performance” in the August 2011, issue.