Tree Fruit Newsletter — August 31, 2023

Apple Maturity at Highmoor Farm

Paulared apples taste great this week.

Zestar was not tested this week.

McIntosh was firm and sour in today’s taste tests. Some of your customers may prefer it this way, but it is not ready to harvest for storage. One of our blocks had seedless apples, probably killed by the May freeze. Seedless apples should not be placed in long-term storage. Seed counts were good in other blocks.

Honeycrisp is not ready to pick for storage and does not have characteristic flavor yet.

Variety Testing Results

Variety Starch Index Delta Absorbance meter reading*
Paulared 4.4 0.79
Gala 1.0 1.28
McIntosh standard Strain 2.3 1.96
McIntosh spur type 3.2 1.94
Honeycrisp 1.0 1.56

* A measure of chlorophyll breakdown in the peel and change in ground color from green to yellow. Numbers decrease as fruits ripen. Gala and Honeycrisp readings between 0.8 and 0.3 indicate sufficient maturity for storage. Standards for other varieties have not been determined. McIntosh readings will remain higher than other varieties throughout the harvest.

Starch index values for McIntosh and Honeycrisp should be considered baseline values at this time since they are generally not ready for harvest until mid Sept.

Predicted McIntosh Harvest Dates

Artichokes growing in a field at Highmoor Farm.
The weather may have given us a tricky apple season, but the cool temperatures were great for our artichoke variety trial. Photo by Dr. Renae Moran

Sanford: Sept. 18
Turner: Sept. 23
Madison: Sept. 26
Caribou: Sept. 24

There is still time to apply ReTain® for extending harvest. It is too late for Pick-Your-Own orchards that will be opening this weekend because ReTain has a 7-day preharvest interval. I expect conditions to be close to ideal for good performance of Retain.

Renae Moran
UMaine Cooperative Extension Tree Fruits Program
University of Maine Cooperative Extension
PO Box 179
Monmouth, ME 04259
(207) 933-2100


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