Honeycrisp Fruit Maturity Report - Sept 25

Monday, September 25, 2023

In this week's Honeycrisp fruit maturity update you will notice that values from our example regions have moved more quickly and are near or nearing optimum maturity. 

Table 1: Maturity indices for regular Honeycrisp fruit sampled in the current year on Sept 25, 2023 and compared with last year's samples where applicable from Sept 27, 2022. The rate of change since last week's measurement is shown in brackets beside the current measurement.

The average starch values for Honeycrisp fruit measured in all regions is nearing the target of 5 especially in Lakeville and North Medford (no ReTain). Maturity continues to be a few days delayed relative to last year. Maturity values are noticeably different between the most mature and least mature fruit on a tree, so actual values would vary depending on what percentage of the fruit is included in the first pick.

The average DA value for Honeycrisp fruit measured in all regions is at or near the target of 0.60. The most mature fruit on the tree are within the harvest window. 

Please note that use of the DA meter on fruit treated with ReTain has not been verified. The DA meter reading on the treated fruit is 0.60 suggesting near-maturity however the starch index values suggest otherwise. Starch index is a more reliable indicator in this case.

Figure 1: Ten-fruit samples across all four locations. The ground/shade colour (left) on the Sept 25 sampled fruit. The visual results of starch-iodine tests on Sept 18/19 (middle) and the change toward more sugars on Sept 25 (right). Average starch ratings are summarized in Table 1.

Important Note - 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 all sides but not from the interior where maturity is expected to be delayed and is most likely targeted for a second pick timing.

About each 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.

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. 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. 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. 

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