Honeycrisp and Ambrosia Fruit Maturity Report - Oct 10

In this week's fruit maturity update the final values are reported for Honeycrisp in select blocks. Honeycrisp harvest is close to wrapping up and in situations where the most mature fruit have been picked and/or Retain has been used, our measurements show that maturity is still acceptable. New to this year I am including Ambrosia in this update. For Ambrosia some blocks are ready for picking and others are nearly ready.

Final Honeycrisp Report

Table 1: Maturity indices for regular Honeycrisp fruit sampled in the current year on Oct 10, 2023 after various percentages of being picked. The rate of change from last week is shown in brackets beside the current measurement where applicable (ReTain trees have not been picked since last measurement).

The average starch values for Honeycrisp fruit that remain still have some starch but are ready for being picked (greater than the target index of 5). ReTain treated trees still have plenty of fruit and they do appear to have delayed starch degradation as we would expect from this tool. 

According to the DA meter, these remaining fruit are not yet ready for harvest however the starch index is a clear indicator of maturity and suggests that the fruit are ready. (The DA meter may not be tested in these second pick situations.)

Ambrosia Report

Table 2: Maturity indices for Ambrosia fruit sampled in the current year on Oct 10, 2023. 

The average starch values for Ambrosia fruit measured in all regions varies. For Ambrosia, the target starch index is greater than 2.8 which has been exceeded at the Rockland block. The target starch index has not been reached at the Lakeville and North Medford blocks.

Similarly, the DA value for Rockland has exceeded the target of 0.47 indicating harvest maturity. Lakeville and North Medford are near the start of the window given by the DA meter measurement. However, starch at Lakeville and North Medford suggests that fruit may not be ready quite yet.

Figure 1: Ten-fruit samples of Ambrosia across all three locations. The visual results of starch-iodine tests on Oct 10. Average starch ratings are summarized in Table 1.

Notes:

Important - This maturity report 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. Fruit representative of size and colour were taken from what is likely targeted for a second pick.

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.

Soluble Solids - Approximates the percentage of sugar content of the fruit. Measured using a handheld refractometer. Values are an average of ten representative samples from each block.

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. 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.