2017 Apple Maturity Assessments – Week Eleven

Apple harvest in 2017 has been well ahead of “normal.” This week we again sampled late-season apples, Cripps Pink (Pink Lady) and Granny Smith.
2017 Apple Maturity Assessments – Week Eleven - News


Both Cripps Pink (Pink Lady) and Granny Smith are ripening, but also showing signs of sun damage from the dry weather in September. Photo: Kathy Hunt, University of Maryland

Cripps Pink

Like many of the apple samples we have tested this year, fruit size in Cripps Pink was relatively small. Cripps Pink fruit continued to lose ground color and increased in red color. While these fruit measured almost 15° Brix, they are still acidic. During the next few weeks their acidity will decrease, leading to a dramatic increase in their sugar-to-acid ratio. While these fruit have not developed much red color yet, the loss of starch in the fruit flesh has begun.

There was some variability in the starch pattern index of the apples (see photo). While most fruit had just lost starch in their core region, a small percentage of those evaluated had also begun to lose starch in the flesh. With cool October weather and this week’s recent rains, the Cripps Pink harvest window should begin at this site in the next week. That will be well ahead of the typical harvest period for Cripps, which has been in early November.

CultivarDiameter (inches)Red Color(%)Ground ColorFirmness (pounds)Soluble Solids (°Brix)Starch Pattern (1-8 scale)
Cripps Pink
Week 10331.8Light Green21.913.72
Week 11338.8Yellowish Green20.114.94.7
Granny Smith
Week 103.20Green18.313.24
Week 113.20Whitish Green18.313.54.9

Granny Smith

The spot-picked Granny Smith apples were larger than the Cripps and appear ready for long-term storage. Starch staining of these apples showed many fruit had lost starch in the core and also in the flesh (See the photo comparing starch patterns on Cripps Pink and Granny Smith).

During these evaluations, we noted two disorders in Granny Smith fruit—sunburn and water core. Like many sites, this orchard received plenty of rainfall during the summer but almost no rainfall in September. While the shaded side of the fruit was still green, the sunny side of many apples was sunburned. This damage ranged from mild peel browning to severe pitting (see photo). The damage was estimated at 20 percent and would be unacceptable for packing. The severe water core we noted in last week’s report was not seen in this week’s samples. While the water core was reduced in Granny Smith, we did note a few open flowers in these trees (see photo).

Cripps Pink (Pink Lady) and Granny Smith apple maturity. Starch staining pattern and red color development of Cripps Pink (upper rows) and Granny Smith (lower rows) apples harvested from tall-spindle plantings at Keedysville, Maryland during the second week of October 2017. Photo: Kathy Hunt, University of Maryland

Granny Smith sunburn. Sunburn development on the sunny side of Granny Smith (upper apple) compared to the shaded fruit below. Fruit were photographed on tall-spindle trees on M.9 Nic29 rootstock during the second week of October 2017. Photo: Kathy Hunt, University of Maryland

Fall flowering in Granny Smith apples. Simultaneous flowering and fruiting in Granny Smith apple trees during the second week of October 2017. Photo: Kathy Hunt, University of Maryland