Tree Fruit Newsletter — October 16, 2023

Apple with bleached spots on the skin.Maturity Report and Update

The photos show unusual markings that have shown up in a few orchards in the northeast. They look like splotches of unblushed peel.  If you have seen this in your orchard, please contact Renae Moran (207-713-7083). She is working with another specialist to narrow down potential causes so that this can be prevented in the future.

McIntosh, Cortland and Honeycrisp at Highmoor Farm have been harvested.

Macoun has progressed to a point where it will not hold up well in cold storage.

Empire has developed good color and sweetness. Starch index of 4 to 6 indicates that it is ok for a few months of cold storage, but may be too ripe for long-term storage.

Apple with bleached spots on the skin.
Apples with unusual markings in the peel

Golden Delicious is the same as Empire.

Northern Spy: Starch breakdown is progressing, and color is good.

Variety Testing Results

Variety Starch Index Delta Absorbance meter reading*
Macoun 4.5 1.46
Empire 4.4 1.09
Golden Delicious 4.8 0.95
Northern Spy 3.1 1.47

*Delta reading is a measure of chlorophyll breakdown in the peel and change in ground color from green to yellow. Standards for these varieties have not yet been developed, but I am reporting them for future reference. Starch index is a measure of starch breakdown, so the index number increases as fruit ripen.

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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