Tree Fruit Newsletter — August 22, 2025
In this newsletter:
- ReTain Reminders
- Fruit Maturity
ReTain Reminders
To extend the harvest, ReTain can be applied 28 to 7 days before anticipated first pick. For orchards in southern Maine, we are about about 21 days from first pick on Macs and Honeycrisp.
ReTain can extend the harvest window by preventing preharvest fruit drop. I anticipate that ReTain effectiveness will be less than normal in orchards that are experiencing water stress. Two applications are allowed, but I do not know how well this will work with the dry conditions. ReTain is more effective when applied as a dilute spray (2X) rather than with a greater concentration.
ReTain can be combined with NAA to prolong drop control. For McIntosh, apply Retain at the full rate with an NAA product at 10 ppm (4 fl. oz. per 100 gals. dilute equivalent) at three weeks before first harvest. A second application may be needed to prolong drop control of McIntosh. Honeycrisp is more sensitive to ReTain than McIntosh and will experience a greater delay in ripening.
Do not apply with calcium chloride as this can burn fruit and foliage.
For more information, visit this PennState website authored by Jim Schupp: Apple PGRs – Prevention of Preharvest Drop in Apple Orchards
Fruit Maturity at Highmoor Farm
Peach varieties that are ready to pick this week:
Donut peaches: TangOs and BuenOs2
Regular peaches: Starfire and an unknown mixed in with July Rose that is probably White Rose
Starch index in Paulred is still 2.2, so no change in starch breakdown since a week ago. However, the Delta Absorbance readings of chlorophyll breakdown have decreased since last week, so this variety is maturing and should be ready to pick next week.
Starch index in Zestar! is 2.1. There were a few fruit with watercore, a sign of water stress. This variety will also be ready to begin picking next week.
Renae Moran
University of Maine Cooperative Extension: Tree Fruits
PO Box 179
Monmouth, ME 04259
(207) 933-2100
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