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 o 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
Not much to say here as everyone is busy with harvest. I will say Honeycrisp reached proper maturity to start harvest mid-week this week. Some reports of McIntosh drop, however, I have seen very little drop on healthy (non-stressed), moderately-cropped McIntosh on dwarf rootstock/tall-spindle plantings. Apple fruit quality is high and the cool temperatures and lack of rain are favorable for a good harvest so far. Keep going...
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 |
|---|---|---|---|---|---|---|---|---|---|
| 9/8/2014 | none |
3.2 |
60 |
16.3 |
11.5 |
1.65 |
3.75 |
wait for better red color | |
| 9/8/2014 | nil |
2.95 |
80 |
15.8 |
10.9 |
1.75 |
3.55 |
start harvest (barely) | |
| 9/8/2014 | Honeycrisp |
few |
3.25 |
70 |
15.8 |
12.6 |
0.53 |
6.6 |
ready to go, 1st pick on red color |
| 9/9/2014 | few |
2.95 |
95 |
17.6 |
12.2 |
1.58 |
4 (3-5.5) |
nice, ready for pick | |
| 9/9/2014 | few |
3.0 |
85 |
17.4 |
12.5 |
1.46 |
4.1 |
nice, ready for pick | |
| 9/9/2014 | few |
3.05 |
65 |
19.3 |
13.2 |
0.46 |
5.4 |
1st-pick ready for sure | |
| 9/9/2014 | none |
2.75 |
90 |
20.8 |
12.2 |
0.16 |
3.9 |
good background color, ready for 1st-pick for sure | |
| 9/9/2014 | none |
2.9 |
92 |
21.5 |
10.6 |
1.01 |
2.6 |
these are still pretty green, wait another 5-7 days | |
| 9/9/2014 | nil |
2.9 |
95 |
20.2 |
10.8 |
0.49 |
3.8 |
background color developing, would like to see higher sugar, worthy of 1st pick | |
| 9/9/2014 | Blondee |
nil |
3.0 |
NA |
20 |
11.6 |
0.31 |
3.7 (2-7) |
start pick any time, very nice quality |
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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The next (and last for 2014) Healthy Fruit (and apple maturity report) will be published on Tuesday, September 23, or thereabouts, 2014. (In two weeks.) 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.