This week's newsletter offers a brief update on Ambrosia fruit maturity and it is the final fruit maturity report for the season. The sites being monitored are ready for harvest. There are times when the DA meter disagrees with other maturity indicators and the DA reading needs to be interpreted with caution. Monitor Ambrosia maturity closely because it can move through the optimal maturity window quickly.
Important Note - The following information about harvest maturity is for general industry purposes only. Growers are encouraged to use their own discretion to harvest trees that are exhibiting delayed colour development or exhibiting maturity indices that disagree with what is being reported here. Values were measured on an average of fruit that were representative of the block's crop load and tree vigour.
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 19, 2026)
Table 1: Maturity indices for Ambrosia fruit sampled in the current year on October 19. Values are compared with the samples taken last week on October 13 in Rockland and Lakeville.
Ambrosia Current Maturity - Table 1 Discussion:
- Ambrosia fruit in the monitored regions are at harvest maturity. For long-term storage, the target starch index range is 2.8 to 5.0. The monitored sites are either the end of this target range or beyond the target.
- This variety can move through the optimal maturity window rapidly (within 1 week) so monitor maturity closely now.
- 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.
- The DA meter reading in Lakeville is not representative of maturity. Other indicators like starch and background colour point to harvest maturity. There are times like this when DA meter values need to be interpreted with caution.
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.
Perennia Food and Agriculture Corp.
Edited by Michelle Cortens, Tree Fruit Specialist
Edited by Michelle Cortens, Tree Fruit Specialist
