Apple pest report

Nope, this isn't a re-send, it really is a new report!

McIntosh Maturity Update

September 8 starch index values provided by Dr. Renae Moran.

Spur type McIntosh: 4.2

Rogers McIntosh at 3.5

Honeycrisp at 4.7 It is recommended that Honeycrisp be picked after a starch index of 5.0, preferably closer to 5.5 for long-term storage. Harvest Honeycrisp at starch index 6.0 to 8.0 for short-term storage or immediate sale.

Research conducted in New York many years ago looked at relationship of temperature to fruit drop, temperature and sunshine to fruit color, average August temperature and susceptibility to low temperature injury in CA storage, and low temperature hours prior to harvest and likelihood of storage scald in long term storage.

Using Highmoor Farm starch index values and weather data, here are some general outlooks for this year's McIntosh harvest. These are only general tendencies to keep in mind. Specific conditions at individual sites have much more influence, and the correlations between weather and these harvest characteristics are not well understood. With those caveats in mind, here are the outlooks:

- Weather conditions that promote optimum fruit color begin Tuesday, September 12

- General outlook (no account for crop load, drought and other stresses) for when drop of sound non-spur McIntosh apples might reach 10% of crop is Friday, September 15 to Wednesday, September 20.

- August mean temperature was more than 1 degree F below the long term average. Observations in Western NY have associated below normal August temperature with increased susceptibility of fruit to Low Temperature Injury during CA storage.

- When fruit have been exposed to 165 chilling hours (hours below 50F) prior to harvest, their susceptibility to storage scald declines, and lower DPA dosage can be used in pre-storage dips. But with maturity running early this year, there will be fewer cumulative chill hours before harvest. Only 46 chilling hours are forecast to have accumulated by September 15.

Happy Harvest!

- Glen

Glen Koehler
Pest Management Office
491 College Avenue
Orono, ME 04473
Voice: 207-581-3882
Email: gkoehler@umext.maine.edu
Web: PRONewEngland.org
Fax: 207-581-3881

TDD 1-800-287-8957

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