Apple Maturity Assessments 2022: Honeycrisp and Gala Week 4
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This is our fourth week of evaluating fruit apple maturity. This week we continued assessing Firestorm Honeycrisp grafted on B9, and included Ultima Gala on M9 (without any plant regulator application) located in the same farm in Smithsburg, MD. Regarding Honeycrisp fruits, as compared to last week, they are advancing in maturity but still not ready for harvest for long-term storage. Ultima Gala fruits harvested from Smithsburg, MD are displaying ~75% of red skin coloration, but very high DA index values and flesh firmness values, with high starch contents, indicating they are still not ready for harvest. The information is summarized in Table 1.
Color
Surface color (eye-balling): Honeycrisp fruits are displaying 35% blush, increasing from last week. Ultima Gala fruits are presenting values ~75% of red skin coloration.
Background color (DA index): Honeycrisp fruits are >1 still and Ultima Gala fruits are displaying values ~1. Readings of 0.6-0.7 are recommended for harvesting fruits for long-term storage, while an index of about 0.35 is targeted for harvesting fruit for short-term storage. Fruits were measured with a DA meter, a device that measures the absorbance difference between 670 nm and 720 nm light. A higher DA index indicates a larger content of chlorophyll-a in the fruit skin.
Firmness
Fruit firmness: Honeycrisp fruit are showing a range of 17.5-18.5 lbs while Ultima Gala fruits are still displaying firmness values > 20 lbs. In general, apples that are destined for long-term storage (>3 months) should be harvested with a firmness of at least 15 lbs; while for fruit for shorter-term storage (1-2 months) a firmness of 13-15 lbs is appropriate. Firmness was measured with a penetrometer with a 7/16-inch diameter plunger.
Starch
Starch content: Honeycrisp and Gala fruits are still ranging from 2.0 to 2.7, respectively. The common starch index rating system (Cornell chart) on a scale from 1 to 8, where 1 is full starch (all blue-black) and 8 is starch-free (no stain), was used. In general, on a 1 to 8 scale, values ranging from 4-6 are recommended for harvesting apples for long-term storage, while 6-7 for fresh market.
Sugars and Acids
Soluble solids contents (SSC): SSC values, measured with a portable refractometer, are showing that this week Honeycrisp and Gala fruits are ranging between 11.8% - 12.5%, with the lowest values assessed for Gala. In general, it is recommended to harvest fruits with readings around 12% to 14% SSC.
Acidity: Honeycrisp fruit is still ~0.7%, while Ultima Gala fruits displayed the lowest acidity values (~0.3), which are typical of this cultivar. A decrease in acidity content is an indicator of advancing maturity, which is the reason this indicator is included in this report. Acidity was measured with an automatic titrator, quantifying malic acid (the major acid present in the juice of apples).
Table 1. Summary table of maturity assessments for Honeycrisp and Gala harvested from Smithsburg, Maryland. Values in parentheses indicate the results from last week’s monitoring.
| Location |
Smithsburg, MD |
Smithsburg, MD |
| Cultivar |
Firestorm Honeycrisp |
Ultima Gala |
| Date |
16 Aug |
16 Aug |
| Rootstock |
B9 |
M9 |
| Diameter (in) |
3.4 (3.2) |
2.9 |
| Skin Red Color (% blush) |
35 (12) |
75 |
| DA Index |
1.1 (1.3) |
1.0 |
| Firmness (lbs) |
18.0 (19.0) |
20.6 |
| Starch Index (Cornell 1-8) |
2.0 (1.5) |
2.7 |
| Soluble Solids (%) |
12.5 (12.0) |
11.8 |
| Acidity (% Malic Acid) |
0.7 (0.7) |
0.3 |
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Smithsburg, MD
Firestorm Honeycrisp
Smithsburg, MD
Ultima Gala
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Macarena Farcuh is an Assistant Professor of Horticulture in the Department of Plant Science and Landscape Architecture. She is interested in investigating how to develop novel strategies for improving fruit quality, nutritional value, shelf-life capacity, safety and marketability throughout fruit development, harvest and postharvest storage. Macarena’s research program integrates diverse approaches, including systems biology, physiology, biochemistry, analytical chemistry, molecular biology, and sensory science. Her goal is to contribute to decrease fruit loss/waste, support environmental sustainability and, at the same time, enhance fruit consumption by meeting consumers’ expectations and thus improve the health and well-being of populations.
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Haley Sater is an agricultural extension agent for Wicomico County specializing in fruit and vegetable production. She is interested in connecting with produce growers across Maryland to identify and promote profitable and sustainable fruit and vegetable systems. Her background is in small fruits and plant breeding.
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Contact Us: Macarena Farcuh, Ph.D.
Assistant Professor and Extension Specialist
University of Maryland, College Park
Email: mfarcuh@umd.edu
or
Haley Sater Ph.D.
Wicomico County Extension Educator
Wicomico County Extension Office
28647 Old Quantico Rd, Salisbury
Email: hsater@umd.edu
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The University of Maryland, College of Agriculture and Natural Resources programs are open to all and will not discriminate against anyone because of race, age, sex, color, sexual orientation, physical or mental disability, religion, ancestry, or national origin, marital status, genetic information, or political affiliation, or gender identity and expression.
Los programas del Colegio de Agricultura y Recursos Naturales de la Universidad de Maryland están abiertos a todos y no discriminará contra nadie debido a raza, edad, sexo, color, orientación sexual, discapacidad física o mental, religión, descendencia, origen nacional, estatus matrimonial, información genética, afiliación política, o identificación y expresión de género.
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