2017 Apple Maturity Assessments – Week Thirteen

We again sampled Aztec Fuji, Cripps Pink (Pink Lady) and Granny Smith this week.
2017 Apple Maturity Assessments – Week Thirteen - News

Updated: July 4, 2018

Aztec Fuji fruit are tree-ripe and 80 percent of the fruit had visible water core around the vascular bundles. The first light frost at Keedysville accelerated red color development in Cripps Pink.

Cripps Turning Pink. Photo: Chris Walsh, University of Maryland

Aztec Fuji

Spot picked Fuji fruit from a tall-spindle planting at Keedysville, MD had about 57 percent red color. While the fruit are not dropping, they have a Light Yellow ground color. Internal measurements of the fruit showed they were 14 pounds firmness with 16 degrees Brix and little starch remaining in their flesh. The Aztec Fuji fruit had varietal flavor with mild water core developing around the vascular bundles in the flesh.

CultivarDiameter (inches)Red Color (%)Ground ColorFirmness (pounds)Soluble Solids (°Brix)Starch Pattern(1-8 scale)
Aztec Fuji
Week 123.245Greenish Yellow14.715.86.5
Week 133.357.5Light Yellow14.4167.4
Granny Smith
Week 103.20Green18.313.24
Week 113.20Whitish Green18.313.54.9
Week 123.30Whitish Green17145.6
Week 133.311.3Whitish Green16.314.45.8
Cripps Pink
Week 10331.8Light Green21.913.72
Week 11338.8Yellowish Green20.114.94.7
Week 123.139.4Yellowish Green18.814.34.7
Week 133.263.8Greenish Yellow19.415.75.8

Granny Smith

The spot-picked Granny Smith apples were larger than the Cripps and ready for long-term storage. Starch staining of these apples showed many fruit had lost starch in the core and flesh (see the photo comparing starch patterns on Aztec Fuji, Cripps Pink and Granny Smith). Despite their loss of starch and increase in soluble solids, these fruit are still quite acidic.

For the past few weeks, we have noted sunburn in many of the Granny Smith fruit we sampled. With this week’s cooler weather many of the Granny Smith apples developed a pink cheek, which masked the sunburn.

Pink color development masking sunburn damage on Granny Smith, Week 13. Photo: Chris Walsh, University of Maryland

Cripps Pink

The red color development and a smooth peel made Cripps Pink the most attractive fruit we evaluated this week. Cripps Pink fruit increased dramatically in their red color during the past week. A week ago we estimated the red color at 39 percent; this week it increased to 64 percent. Rainfall earlier in the week increased fruit size noticeably, but also caused small cracks in the stem end of the largest fruit.

The Cripps fruit are still firm, but losing starch in their flesh. Their soluble solids were 15.7 degrees Brix, which is almost the same as Aztec Fuji. Despite this high level of sugar, the Cripps still taste acidic. This makes them acceptable for storage but not necessarily ready for direct marketing.

Aztec Fuji, Cripps Pink and Granny Smith Apple Maturity – Starch staining pattern and red color development of Aztec Fuji (left), Granny Smith (center), and Cripps Pink (right) spot-picked apples from Keedysville, Maryland during the last week of October, 2017. Photo: Kathy Hunt, University of Maryland

Authors

Tree Fruit Cultural Practices and Production Systems Sustainable Specialty Crop Production Support for Next Generation Farmers from Diverse Backgrounds

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Christopher S. Walsh