Ambrosia Fruit Maturity Report
Ambrosia fruit were taken from throughout the trees to target a one-pick harvest to strip the trees.
Ambrosia Current Maturity (Oct 13, 2026)
- Ambrosia fruit in the monitored regions are currently within the optimal harvest maturity window for long term storage. For long-term storage, the target starch index range is 2.8 to 5.0. Most regions are at the early end of this target range.
- This variety can move through the optimal maturity window rapidly (within 1 week) so monitor maturity closely now.
- The high crop load in Lakeville might be contributing to elevated starch index ratings. With a heavy crop, less starch may be allocated to individual fruit, leading to more rapid starch depletion. However, the fruit background colour remains relatively green, suggesting fruit may be less mature than the starch index alone indicates.
- Due to the preharvest rain, soluble solids may be a little diluted but not terribly, and varietal flavour is still good. The target of 12% brix might not be achievable in all situations.
- Fruit in Rockland and North Medford exhibit a cream-coloured background, which is a strong indicator of harvest maturity.
- DA meter readings also indicate that fruit in Rockland and North Medford are mature. In Lakeville, however, DA meter values appear less reliable when compared with other maturity indicators and should be interpreted with caution.
Ambrosia Historical Comparison
- Starch index values can vary depending on crop load and explain some of the observed variation.
- Current starch index measurements indicate that fruit maturity is similar to or slightly more advanced than levels reported in AAFC data from 2011, 2012, and 2013.
- Although North Medford was not included in my 2024 comparison dataset, its starch index values, soluble solids, and DA readings are closely aligned with the historical averages reported by AAFC researchers across 2011, 2012, and 2013, suggesting a comparable stage of maturity.
About each maturity measurement:
Starch Index - Starch is converted to sugars as ripening progresses. The starch-iodine test is used because iodine binds to starch molecules turning them blue/black, whereas sugars are not stained and remain clear. The Cornell chart on a scale of 1 to 8 was used above and values are an average of ten representative samples from each block. The target for long term storage for Honeycrisp is 5.0 to 7.5 and for Ambrosia is 2.8 to 5.0.
Soluble Solids - Approximates the percentage of sugar content of the fruit. Measured using a digital refractometer. Values are an average of ten representative samples from each block taken on the blush side of each fruit. Soluble solids values in our region at harvest maturity for Honeycrisp tend to be 11% brix and for Ambrosia are 12% brix.
DA Meter - The delta absorbance (DA) value is related to the chlorophyll content of the peel. AAFC researchers in Kentville developed a protocol for Honeycrisp and Ambrosia.
- For Honeycrisp, values above 0.60 are immature, values 0.6 to 0.36 are ideal for long term storage, and values below 0.35 are best for short term storage because they are more prone to storage disorders.
- For Ambrosia, values above 0.47 are immature, values 0.47 to 0.28 are ideal for long term storage, and values below 0.28 are best for short term storage because they are more prone to storage disorders.
- Values shown above are the average of twenty fruit taken throughout a block, with readings taken on the transition area between the sun and shade exposed sides. DA values will be noticeably different between the most mature and least mature fruit on a tree.
Edited by Michelle Cortens, Tree Fruit Specialist






















