Jon Clements, Editor
Horticulture -- Apple Maturity Report
Harvest maturity target indices
Key insect life cycle and management dates
Note: for 2014, we have four Massachusetts orchard locations subscribed to AR: Belchertown, Groton, Phillipston, and Sutton. The website for looking at AgRadar for these locations is: http://extension.umaine.edu/ipm/programs/apple/pestcasts/
Preliminary McIntosh Harvest Date Forecasts -- Date to apply ReTain to delay first harvest of apples which without treatment would be ready for storage harvest on September 8 is from Monday, August 11 to August 18. Date to apply ReTain to delay maturity for 2nd, 3rd, or 4th pick of those apples without delaying start of harvest maturity, is from Monday, August 25 to September 1. Begin measuring actual McIntosh starch-iodine no later than Friday, August 29. The Michigan formula estimates that non-spur McIntosh will reach starch index 4.0 and start the optimum harvest window for long-term storage on Wednesday, September 10. Using the Hudson Valley, NY formula, McIntosh maturity is forecast to reach starch index 6.0 in Belchertown, MA on Friday, September 26.
Jon Clements
I don't think we have seen a more favorable harvest season in many years in terms of cool temperatures and lack of precipitation. The apples are in "suspended animation" on the trees, ripening rather slowly, but nonetheless moving towards their demise. Very little should have impeded your harvest progress. I have been wondering if the very dry conditions might affect the trees, but I guess if you are really worried about it, you could turn some irrigation on. Very little transpiration is happening now, so I don't think it is an issue. If anything, lack of water should help concentrate sugars in the fruit. Trees under stress, however, are more likely to suffer winter injury. (Do you believe the prediction of a very cold and snowy winter?)
This will be the last official Healthy Fruit for 2014. Subscribers will continue to receive meeting notices and other important updates throughout the year. Otherwise, see you next spring and thanks for your support.
Note: updated apple maturity report always available on UMass Fruit Advisor. All apples tested from UMass Orchard, Belchertown, MA unless otherwise noted.
| date | Cultivar | pre-harvest drop | fruit diameter inches | color % red | firmness lbs | soluble solids | DA Index | starch index | comments |
|---|---|---|---|---|---|---|---|---|---|
| 9/23/2014 | Thome Empire | none |
3.1 |
95 |
17.5 |
12 |
1.26 |
3.5 |
good look, but needs another 5-7 days to develop maturity |
| 9/23/2014 | Rubinstar Jonagold | nil |
3.5 |
70 |
16 |
13 |
1.11 |
5 |
signs of sunburn/radial watercore; otherwise nice, could start harvest over next week |
| 9/23/2014 | Royal Court Cortland | none |
3.6 |
92 |
15.4 |
13.7 |
1.32 |
3 |
nice, good sugar |
| 9/23/2014 | Snappymac McIntosh | some |
3.1 |
92 |
15.5 |
12.5 |
1.38 |
4.8 |
nearing the end of window for CA harvest. although cool temps have preserved maturity and limited drop |
| 9/23/2014 | Honeycrisp | some |
3.45 |
60 |
13.6 |
11.6 |
0.54 |
6.4 |
wish sugars were a little higher, but in the Honeycrisp sweet spot; harvest immediately assuming red color |
| 9/23/2014 | Macoun | nil |
3.1 |
70 |
18.1 |
11.3 |
1.76 |
3.4 |
really needs another week to develop varietal flavor and quality |
| 9/23/2014 | Buckeye Gala | nil |
2.9 |
98 |
19.4 |
12.6 |
0.46 |
5 |
on it's last legs |
Adapted from Eastern NY Commercial Horticulture Program, Tree Fruit News, Vol. 2, Issue 12, September 4, 2014, Dan Donahue; and Jon Clements (personal observation)
Following are "target" harvest indices for some of the more popular commercial apple varieties. Always use your best judgment when deciding when to harvest, but most fruit should fall within these indices for proper harvest maturity and best fruit quality.
| Cultivar | pre-harvest drop |
color % red |
firmness lbs |
soluble solids (brix) |
DA index |
starch index (Cornell chart) |
comments |
| Gala | nil |
≥50 |
18-20 |
≥12 |
NA |
4-7 |
ground color changes to cream; flavor develops |
| McIntosh | just starting |
≥50 |
15-18 |
≥12 |
NA |
4-6 |
red color development critical, but just because it is red does not mean it is ready for pick (or does it?) |
| Honeycrisp | minimal |
≥50 |
≥14 |
≥13 |
0.60 to 0.40 |
6-7 |
watch for background color change and minimal drop, good color development, requires at least two picks |
| Cortland | none |
≥50 |
≥15 |
≥12 |
NA |
2.5-3.5 |
always starch tests low despite being ready to pick |
| Empire | nil |
≥50 |
≥17 |
≥12 |
NA |
4-6 |
|
| Jonagold | nil |
≥50 |
≥16 |
≥14 |
NA |
6-7 |
|
| Delicious | nil |
≥80 |
≥17 |
≥12 |
NA |
3-5 |
|
| Mutsu/Crispin | nil |
NA |
≥17 |
≥14 |
NA |
4-5 |
You may be unfamiliar with the DA index. It comes from a DA Meter (Turoni, http://www.trturoni.com/en/content/8-da-meter). It measures the amount of chlorophyll left near the fruit surface. Apples (and peaches) lose chlorophyll and green color as the fruit ripens. The DA Meter puts a value on this loss of chlorophyll, and some standards have been developed on when to start and end harvest based on the DA index. For example, Honeyscrisp is suggested to start harvest when the DA index is 0.60 and end harvest when it reaches 0.40. Thanks to Mass. Fruit Growers' Assoc. Horticultural Research Fund/Foundation for purchasing the DA Meter ($4,000).
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This will be the last official Healthy Fruit for 2014. Subscribers will continue to receive meeting notices and other important updates throughout the year. Otherwise, see you next spring and thanks for your support. As always feel free to get in touch with any member of the UMass Fruit Team (http://extension.umass.edu/fruitadvisor/team-members) if you have questions or comments.