This is the fifth maturity update for Honeycrisp and the first update for Ambrosia using the example regions. The Honeycrisp fruit being monitored are within the window of optimal maturity. Soluble solids that represent sugars are higher this year relative to last year. ReTain-treated fruit are delayed in maturity as expected. In Ambrosia, some minor starch movement and good sugar content is reported especially in cases of lower-than-target crop load. If labour issues are anticipated, ReTain or Harvista may be considered.
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
Only when the first-pick already occurred were second-pick fruit sampled from the interior of the canopy, where maturity is expected to be delayed.
Table 1: Maturity indices for regular Honeycrisp fruit sampled in the current year on Monday, Sept 23 2024. Values are compared with the samples taken last week on Sept 16 to estimate a weekly rate of change. Please note that new factors are introduced this week including ReTain at the Rockland site and first pick in Lakeville.
Table 1 Discussion:
- First-pick fruit are optimally mature for long term storage at starch index values that are now around 5.0 at the monitoring region in Rockland.
- In Rockland, it is unlikely that the ReTain influenced the maturity of the first pick fruit but should influence later picks.
- 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.
- Where ReTain was used 3 weeks before the anticipated harvest in North Medford, starch index values are relatively low near 3 after a slow increase from last week.
- DA meter values have changed little over the last week and starch index values have caught up to align better with DA meter predictions for optimal maturity.
- However, the ReTain-treated fruit are not yet mature according to the starch index, meaning that the DA meter value is misaligned with ReTain treatments. The DA meter was developed as a tool based on the relationship between chlorophyll degradation and the rate of change of maturity indices. 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 are currently 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, but the following can be gleaned.
- Starch index continues to be higher at this point in time when compared to 2023, meaning that maturity is ahead. However, the North Medford block that was treated with ReTain last year and this year at 1/2 rate on Aug 29 is maturing at a very similar rate to 2023.
- All regions have fruit with higher sugar content this year relative to last year.
- Where labour issues are anticipated, Harvista may be applied to temporarily halt maturity progression on first or second picks (ideally when starch index is 4.0 to 6.0). At this time, ReTain should only be considered if the block is 1 week or more away from harvest maturity in order to delay maturity of the later picked fruit. The preharvest strategy table is available on our website.
More observations (data not shown):
- Red blush colour is progressing well this year overall, however, only a minor increase was recorded over the last week.
- Fruit treated with ReTain generally have less colour but are also correspondingly at an earlier stage of maturity.
- The fruit size across my samples averaged 220 g and growing at a rate of +5.5g/wk. The diameter was an average of 79 mm/3.11 inches and had stayed relatively constant over the last week. 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 Monday, Sept 23 2024.
Table 2 Discussion:
- The starch has begun to convert to sugars so the starch index is higher than the base level of 1.0. 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. Starch index values are currently below 2.8.
- When harvested late, the fruit are at greater risk of developing greasiness, rot, core flush, and senescent breakdown in storage.
- ReTain may still be applied this week or next if labour issues are anticipated, and Harvista is an option on shorter-notice.
- Similar to the DA value in the context of Honeycrisp, there may be a misalignment with Ambrosia so starch index should be monitored. Updates will be provided next week.
- Soluble solids values in our region for Ambrosia tend to be 12% at around optimum harvest maturity but again it depends on crop load.
- Where there is already minor 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 20% on the entire tree for a one-pick harvest.
- Remember that if colour is progressing better than it has in recent years, just be cautious about harvest maturity. In some cases high colour encourages harvest of immature fruit.
- The fruit size in my samples averaged 207 g. The diameter was an average of 77 mm/3.03 inches. 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.
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:
- Market Opportunities and Diversification -*Newly Opened
- Limestone Trucking Assistance Program Application Deadline: September 30, 2024
- Get Growing Program - Application Deadline: September 30, 2024
- Young Farmer Mentorship Program *Extended Application Deadline: October 8, 2024, the website will reflect this change shortly*
- Speaker Series Assistance Program
- Plant your Roots
- Organic Certification Rebate Program
- Agriculture Skills Student Bursary Program
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
