Apple Maturity Assessments 2022: Honeycrisp and Gala Week 6
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We are entering our sixth week of evaluating fruit apple maturity. This week we continued assessing Firestorm Honeycrisp grafted on B9, and Ultima Gala on M9 located in the same farm in Smithsburg, MD. None of these fruits have received any plant growth regulator. In general, Ultima Gala fruits are ready for harvest for short-term storage or fresh market with flesh starch disappearance values of 6.0, firmness values ~18 lbs, DA index values <0.5, skin red coloration ~90% and soluble solids contents >13%. Firestorm Honeycrisp fruits should continue to be harvested as this week fruits are displaying average starch index values of 5.5, firmness values in the range of 15 lbs, skin red coloration ~50% and soluble solids contents >14.0%, indicative of fruits for short-term storage or fresh market. The information is summarized in Table 1.
Color
Surface color (eye-balling): Honeycrisp fruits are displaying 50% of red skin coloration, slightly increasing their values as compared from last week’s evaluation. Ultima Gala fruits are presenting values ~90% of red skin coloration.
Background color (DA index): Honeycrisp fruits are displaying values ~0.7, while Ultima Gala fruits presented a significant decrease in their values to <0.3. 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: Firestorm Honeycrisp fruits continued displaying a decrease in firmness values and reached ~15 lbs this week, while Ultima Gala fruits also decreased their firmness values to ~18 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: Firestorm Honeycrisp are displaying starch disappearance values of 5.5 and Ultima Gala fruits values of ~6, indicative of fruits that are ready for harvest for short-term storage or fresh market. 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 3.5-5 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 Firestorm Honeycrisp and Ultima Gala fruits are averaging 14.2% and 13.3%, respectively. In general, it is recommended to harvest fruits with readings around 12% to 14% SSC.
Acidity: Honeycrisp fruit are ~ 0.65% acidity this week, while Ultima Gala fruits displayed acidity values of ~0.3, which are typical of this cultivar. A decrease in acidity content is an indicator of advancing maturity, reason why 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 |
29 Aug |
29 Aug |
| Rootstock |
B9 |
M9 |
| Diameter (in) |
3.6 (3.5) |
3.0 (3.0) |
| Skin Red Color (% blush) |
50 (45) |
90 (85) |
| DA Index |
0.7 (0.9) |
0.2 (0.5) |
| Firmness (lbs) |
15.0 (17.0) |
18.0 (19.3) |
| Starch Index (Cornell 1-8) |
5.5 (3.5) |
6.0 (4.5) |
| Soluble Solids (%) |
14.2 (13.3) |
13.3 (12.7) |
| Acidity (% Malic Acid) |
0.65 (0.7) |
0.3 (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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