Honeycrisp and Ambrosia Fruit Maturity Report - Oct 7

Monday, October 7, 2024

Maturity updates are wrapping up for the remaining Honeycrisp fruit (treated with ReTain) and therefore the majority of this update focuses on Ambrosia fruit. In Ambrosia, harvest maturity approaches or may have begun depending on the crop load of a particular block. When harvest maturity begins there is a window of time before fruit are considered overmature for storage purposes (see the post for estimates on the rate of change of the starch index). The Ambrosia sugar content represented by soluble solids has reached optimal values. 


Important Note - The following information about 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. Fruit representative of size and colour were taken from all sides of the tree. 


Honeycrisp Fruit Maturity Report

The following Honeycrisp information represents the remaining fruit where maturity is slightly delayed relative to first-pick fruit.

Table 1: Maturity indices for regular Honeycrisp fruit sampled in the current year on Monday, Oct 7 2024. Where possible, values are compared with the samples taken last week on Oct 1 to estimate a weekly rate of change.


Table 1 Discussion:
  • Fruit treated with ReTain at 3 weeks prior to expected harvest that remain after the first-pick are still within optimal maturity. They are not overmature as they have not exceeded starch index value of 7.5. Late harvest beyond starch 7.5 results in fruit in storage with more soft scald.
  • Soluble solids values in our region for Honeycrisp tend to be 11% at around optimum harvest maturity but it depends on crop load.


    Ambrosia Fruit Maturity Report

    Fruit were taken from throughout the trees to target a one-pick harvest to strip the trees.

    Table 2: Maturity indices for Ambrosia fruit sampled in the current year on Monday, Oct 7 2024. Values are compared with the samples taken last week on Oct 1 to estimate a weekly rate of change.


    Table 2 Discussion:
    • Local research by John Delong et al. 2013 showed that optimal values of the starch index for long-term storage of Ambrosia are between 2.8 and 4.5. When harvested late, the fruit are at greater risk of developing greasiness, rot, core flush, and senescent breakdown in storage. 
      • Starch index values are now within the window of harvest maturity in the example region in Rockland and are nearing the start in Lakeville and North Medford. 
      • The starch index value is showing a rate of change of +0.7 wk in areas untreated with Harvista. There will be a window of opportunity before the fruit exceed starch index 4.5. According to the current rate of change, the harvest maturity window could be 2 weeks.
      • The Lakeville region that was treated with Harvista at about 1 week before anticipated harvest does appear to have slowed down in the rate of change of starch index, being only +0.3 over the last week. It may have bought some time.
    • Similar to the DA value in the context of Honeycrisp, there is a misalignment with Ambrosia so starch index should be monitored.
    • Soluble solids values in our region for Ambrosia tend to be 12% at around optimum harvest maturity but again it depends on crop load. The soluble solids are currently optimal in all regions being monitored.
    • Where there is advanced starch movement and above-average soluble solids representing sugar content in the regions being monitored, it is due in part to lower-than-target crop load.

    More observations (data not shown):
    • Red colour is averaging around 57% on the entire tree for a one-pick harvest.
    • The fruit size in my samples averaged 220 g and is fairly similar to last week. The diameter was an average of 79 mm/3.11 inches and is similar to last week. However, this information is highly dependent on the crop load in a particular block.

    Table 3: Maturity indices for Ambrosia fruit relative to samples taken last year on Oct 10, 2023.

    Table 3 Discussion:
    • Starch index is higher this year meaning that maturity is slightly ahead.
    • Soluble solids vary, likely related to crop load.
    • The DA meter values are lower this year meaning that the DA meter also predicts advanced maturity but note comments above about possible misalignment of actual DA values with actual fruit 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.

    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.

    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. 

    Notices


    NSDA Programs 

    Programs staff would like to inform clients that applications are being accepted at this time for the following 2024-2025 programs. Programs for the 2024-2025 year, along with their applications and guidelines can be found by clicking the following links:
    For more information on these programs please contact your local Ag Rep.



    Perennia Food and Agriculture Corp.
    Edited by Michelle Cortens, Tree Fruit Specialist

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