Maturity updates continue for the remaining Honeycrisp fruit after the first-pick including those treated with ReTain or not, in the example regions. The remaining Honeycrisp fruit are relatively less mature than first-pick fruit but are still at or near maturity and may just require more red colour to develop. In Ambrosia, starch conversion to sugars continues and fruit approach the start of harvest maturity in some situations, especially in historically early blocks and those with low crop load.
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. The rate of change is not stated where fruit were picked between this week and last week's measurements. The Lakeville rate of change represents the change in maturity of the remaining fruit because those same fruit were reported last week.
Table 1: Maturity indices for regular Honeycrisp fruit sampled in the current year on Tuesday, Oct 1 2024. Where possible, values are compared with the samples taken last week on Sept 23 to estimate a weekly rate of change. Please note that new factors are introduced this week including first pick in Rockland and North Medford.
Table 1 Discussion: There are many factors at play but here's what I can glean for general guidance...
- Fruit remaining after the first-pick of 60-75% in the example regions are not overmature as they have not exceeded starch index value of 7.5.
- In the Lakeville example, the remaining fruit without ReTain may have only one more week until they become overmature for long-term storage.
- In Rockland, there is no untreated comparison but ReTain applied 1 week before anticipated harvest may have slightly delayed the maturity of the remaining fruit.
- Where ReTain was used 3 weeks before the anticipated harvest in North Medford, starch index values of the remaining fruit are relatively low near 4, seemingly offering some additional time to harvest.
- Local research by John Delong et al. 2013 showed that optimal values of the starch index for long-term storage for Honeycrisp are between 5.0 and 7.5. Early harvest of Honeycrisp before starch 5.0 can lead to more bitter pit in storage whereas late harvest beyond starch 7.5 results in more soft scald.
- DA meter values are not consistently aligned with starch so refer to starch comments above. The rate of change is different in ReTain-treated fruit so the standard DA meter values for optimum maturity do not apply to ReTain-treated fruit.
- Soluble solids values in our region for Honeycrisp tend to be 11% at around optimum harvest maturity but it depends on crop load. The soluble solids of the remaining fruit are near-optimal.
- Crop load always has an influence. More vegetation relative to less crop will result in more resources for colour and advanced maturity. The crop load in the blocks being monitored is slightly lower than target.
- It becomes increasingly difficult to make historical comparisons as harvest progresses because of the variable factors like ReTain and first pick dates/percentages. However, it appears as though starch index continues to be higher at this point in time when compared to 2023, meaning that maturity is ahead.
More observations (data not shown):
- Red blush colour on the fruit remaining after first-pick currently averages 45-50%. In Lakeville the fruit remaining after first pick increased in colour by 10% over the last week. Two sites were treated with ReTain so the product may influence colour if maturity is also delayed.
- The fruit size across my samples averaged 238 g and 81 mm/3.2 inches in diameter. In Lakeville, the remaining fruit grew at a rate of +11.5g/wk and +0.7 mm(0.03")/wk. However, this information is highly dependent on the crop load in a particular block.
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 Tuesday, Oct 1 2024. Values are compared with the samples taken last week on Sept 23 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 nearing 2.8 in some of the example regions and there will be a window of opportunity before the fruit exceed starch index 4.5.
- The starch index value is showing a rate of change of +0.5 to +1.0/wk. The fastest rate of +1.0/wk appears in conjunction with the fruit of advanced maturity. The current rate of change suggests a 2-week window and updates will be given next week.
- If labour issues are anticipated, Harvista may be an option on up to 3 days before harvest.
- 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 the Rockland and Lakeville example regions.
- Where there is advanced starch movement and good 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 45% on the entire tree for a one-pick harvest.
- The fruit size in my samples averaged 223 g and growing at a rate of +16g/wk. The diameter was an average of 79 mm/3.11 inches and growing at a rate of +2 mm/+0.08 inches/wk. However, this information is highly dependent on the crop load in a particular block.
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.
- 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
Edited by Michelle Cortens, Tree Fruit Specialist
