Tree Fruit Newsletter — August 11, 2026

August 12, 2026 Tree Fruit Newsletter

In this newsletter:

  • Predicted harvest dates for McIntosh apples
  • Fruit Drop Control
  • Harvest Maturity in Peach and Apple Varieties

Predicted McIntosh Harvest Date

Predicted ‘first pick’ for McIntosh apples at Highmoor Farm is September 13 and a few days before that for orchards in southern Maine. The predicted end of harvest for long-term storage is September 28 at Highmoor Farm and September 23 in southern Maine. Predictions are based on temperature in the weeks after bloom. This prediction is intended for scheduling ReTain and other harvest management decisions. Actual harvest dates should be based on measurements of fruit maturity closer to the actual harvest date.

The heavy crop load can delay fruit ripening by several days. This may impact when ReTain should be applied.

Fruit Drop Control

Three plant growth regulators can be used to delay fruit drop, ReTain, NAA and MCP (Harvista). ReTain is the most widely used ‘stop drop’, but is commonly combined with NAA for varieties prone to severe fruit drop such as McIntosh.

ReTain can be combined with NAA (PoMaxa) to prolong fruit drop control in high-risk varieties. For McIntosh, apply Retain at the full rate with an NAA product (Fruitone, PoMaxa) at 10 ppm (4 fl. oz. per 100 gals. dilute equivalent) three weeks before first harvest. A second application may be needed to prolong drop control of McIntosh. Honeycrisp and Gala are less prone to early fruit drop and do not require the full rate of ReTain for fruit drop control and do not need the addition of NAA.

General use guidelines for ReTain include:

  • Application timing will depend on how you want to manage the harvest. Application 4 weeks before the start of harvest will delay ripening in the “first pick” apples, but will wear off by the end of harvest. Use this timing to delay harvest of the entire block and make a second application if needed.
  • Application 2 to 3 weeks prior to the start of normal harvest is the common timing for most with a second application in high-risk orchards.
  • Application at 7 days before harvest will have little impact on ripening in the “first pick”, but will delay fruit drop in the apples that would be harvested last.
  • ReTain has a 7-day preharvest interval (PHI) and a 12-hour reentry interval (REI).
  • Use one pouch (or less) per acre in each application; two applications are allowed.
  • On Honeycrisp and Gala, consider using reduced rates — early application of ReTain can inhibit color development on these varieties.
  • Use an organosilicone surfactant at a concentration of 0.05 to 0.1% (6.4 to 12.8 oz surfactant per 100 gallons water) with ReTain, do not apply when temperature exceeds 85 °F.
  • Dilute applications are recommended, up to 2X concentration or 100 gallons per acre.
  • Apply during slow drying conditions such as in the evening to allow for maximum uptake.
  • Avoid application when rain is expected within 12 hours.
  • ReTain will not work on trees suffering from stress.
  • Avoid application with calcium chloride or captan as phytotoxicity has been observed.

Peach Maturity

Peaches left to fully ripen on the tree will be impossible to harvest without skin tearing based on my experience in the last four years. This year, we have been picking them when firmness is close to 10 lbs. when measured with a fruit penetrometer, and this has been working well. However, excessive softening and bruising occurred when peaches were held at the warm temperatures that occurred last week. Fruit loss from excessive bruising can occur if fruit cannot be sold within three days. Cold storage has been preventing this.

Desiree was harvested July 30 when flesh firmness average 10 lbs. Fruit size in this variety has been unacceptably small.

July Rose and Summer Serenade were harvested August 10 when firmness was 6 to 12 lbs. Fruit size in Summer Serenade has been good for an early variety.

PF 8Ball will be ready to harvest this week.

Apple Maturity

Pristine harvest began August 10.

 

Renae Moran

University of Maine Cooperative Extension: Tree Fruits

PO Box 179

Monmouth, ME 04259

(207) 933-2100

rmoran@maine.edu

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