Healthy Fruit, Vol. 22, No. 17, August 26, 2014

Jon Clements, Editor


Upcoming pest events


The way I see it


Horticulture -- Apple Maturity Report

Guest article -- Harvest Indicators and Storing Honeycrisp

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Useful links

Upcoming pest events

Degree days Base 43 Belchertown, MA (UMass Orchard) as of 25-August, 2014: 2,989

Coming events
Degree days (Base 43)
Codling moth 2nd flight peak
Lesser appleworm 2nd flight peak
Obliquebanded leafroller 2nd flight peak
Redbanded leafroller 3rd flight peak
Oriental fruit moth 3rd flight peak
Spotted tentiform leafminer 3rd flight peak
Apple maggot flight subsides
Peachtree borer flight subsides
San Jose scale 2nd gen. crawlers emerging


Key insect life cycle and management dates

Note: for 2014, we have four Massachusetts orchard locations subscribed to AR: Belchertown, Groton, Phillipston, and Sutton. The website for looking at AgRadar for these locations is:

Codling moth (CM) -- Codling moth development as of August 13: 2nd generation adult emergence at 79% and 2nd generation egg hatch at 43%. 2nd generation 30% CM egg hatch: August 9, Saturday - target date where one spray needed to control 2nd generation CM.

White apple leafhopper (WAL) -- 2nd generation WAL found on apple foliage: August 9, Saturday.

Apple Maggot Fly (AMF) -- Rough guess of peak AMF trap captures is: August 2, Saturday.

Preliminary McIntosh Harvest Date Forecasts -- Date to apply ReTain to delay first harvest of apples which without treatment would be ready for storage harvest on September 8 is from Monday, August 11 to August 18. Date to apply ReTain to delay maturity for 2nd, 3rd, or 4th pick o those apples without delaying start of harvest maturity, is from Monday, August 25 to September 1. Begin measuring actual McIntosh starch-iodine no later than Friday, August 29. The Michigan formula estimates that non-spur McIntosh will reach starch index 4.0 and start the optimum harvest window for long-term storage on Wednesday, September 10. Using the Hudson Valley, NY formula, McIntosh maturity is forecast to reach starch index 6.0 in Belchertown, MA on Friday, September 26.

The way I see it

Jon Clements

This issue of Healthy Fruit kind of ends the pest management season and begins the harvest season. (Although I noted an apple maggot fly adult on Ginger Gold apples yesterday while collecting a sample to assess maturity.) Note the apple maturity report below and always available on the UMass Fruit Advisor.

I have had some complaints about water core (pictured left iin Akane apple) and moldy core of apple. Watercore can appear when apples are left on the tree to over-mature, although some varieties (Paulared, Delicious, Fuji among others) are more susceptible to water core. Large fruit size also pre-disposes fruit to watercore. Environmental conditions (hot weather, sun exposure) can also enhance water core development. Apple trees that are out-of-balance (i.e., excessive vegetative growth) therefore with less calcium in the fruit may also have more water core apples. There is not much you can do about it, except try to harvest early (vs. late) where you think you might have a problem. And grow "calm" trees. (Makes the case for dwarf rootstocks.) Also consider the fact some people actually might prefer an apple with watercore because they are perceived as being sweeter. For more information on water core, see:

Moldy core results when fungi invade an open calyx. Moldy core can initiate at petal fall, so fungicide sprays are recommended then for apple varieties that typically exhibit moldy core symptoms, such as Ginger Gold, Cameo, Golden Delicious, and Idared. Moldy core can be more prevalent with light fruit set, and when it is dry early summer followed by rains late summer, or when it is wet during bloom and petal fall. (Describes this year pretty good.) Good, sound fruit should not be adversely affected by moldy core. For more information on moldy core see:


Jon Clements

See Upcoming Pest Events and AgRadar for current pest status.

Horticulture -- apple maturity report

Note: updated apple maturity report always available on UMass Fruit Advisor. All apples tested from UMass Orchard, Belchertown, MA unless otherwise noted.

This week I will begin an apple maturity report. Next week I will start McIntosh, Honeycrisp, and Gala. This year I have added the DA index which is the reading obtained with a DA Meter. (Thanks to funding from the UMass Horticultural Research Fund.) The DA meter measures the chlorophyll contact (or lack of it) in fruit. Lower readings mean less chlorophyll and (generally) higher maturity, although absolute maturity values indicating start and end of harvest have not been established for all varieties. (Except for Honeycrisp, more on that next Healthy Fruit.) 

date Cultivar pre-harvest drop fruit diameter inches color % red DA index firmness lbs soluble solids starch index comments
8/25/2014 Akane nil 2.85 75 0.91 18.5 11.9 3.9 needs another week; significant stem and calyx russet
8/25/2014 Minneiska nil 2.95 65 0.51 17.3 12.8 3 a tart SweetTango right now, needs another week; some russet
8/25/2014 Dandeered significant 3.25 95 1.22 14.6 12.1 4 touch of watercore; kind of touchy in terms of drop/maturity, probably should have been already picked
8/25/2014 Ginger Gold none 3.25 0 0.95
19.6 12.4 2.9 (does not test well) beginning peak Ginge Gold harvest; some signs of sun over-exposure; observed AMF on fruit while picking


date Cultivar pre-harvest drop fruit diameter inches color % red DA index firmness lbs soluble solids starch index comments
8/21/2014 Zestar! few 3.2 50 0.73 15.2 13.9 3.5 (barely) ready for first pick
8/21/2014 Sansa nil 2.95 65 hint stripe 0.36 16.4 12.5 3.5 (2-4) crew picking, not much background green; heavy crop affects eating quality
8/21/2014 Ginger Gold none 3.25 0-10 hint pink 0.94 20.5 12.4 2 (1-3) not quite ready to pick
8/21/2014 Paulared few 3.3 50 1.09 15.4 11.2 3 solid some watercore; tart apple
8/22/2014 Paulared
some 3.4 50 1.26 13.8 10.8 4 (3-6) fairly sweet juice; 6/10 significant watercore

Guest Article

Harvest Indicators

Mary Concklin, Visiting Associate Extension Educator - Fruit Production & IPM, University of Connecticut

With harvest just beginning and already underway on some farms, it is a good time to review the indicators of optimum harvest as well as dealing with Honeycrisp.

Harvest Indicators

Indicators for optimum harvest time vary by variety, seasonal weather, and position within the tree canopy.  Optimum harvest also varies by whether the fruit is going into CA storage – long or short, cold storage or picked for immediate sale (PYO, farm market, etc). There are several tools available to help determine maturity – all of which can be done in the field. Choose fruit from the same area within the tree canopy each week you test because fruit on the inside of the canopy will test differently than those on the outside. Fruit exposed to sun matures at a different rate than fruit in the shade, and so on.

 The Starch-iodine test is very useful tool to indicate the progression of the change from starch to sugar within apples. As apples mature the starch is converted to sugar. This test is often used by itself for several varieties including Mac, Cortland, Empire, and Delicious. Not a good indicator for Fuji. A very good publication by Dave Blanpied and Ken Silsby, Cornell, ( has information about the starch-iodine test, as well as colored pictures for indexing maturity and optimum harvest window for your market or storage plans. (Ed. note: you may also want to see: Painless and Efficient Maturity Testing

 A refractometer is also a valuable tool to measure the sugar content within the fruit. They can be purchased on eBay,, Fischer Scientific, and many others, for less than $100 to over $200. Squeeze some of the juice onto the prism, look through the lens and read the percentage of soluble solids or sugar. Readings between 10%-13% appear to be optimum for Macs going into regular storage. (Ed. note: Although expensive, I highly recommend a digital refractometer.)

 Fruit firmness is a good indicator for CA storage cut-off but is rarely used alone. 15#-16# or firmer with high sugar content is good for CA storage (this varies by variety). Softer fruit will probably not hold up well in long-term storage. Softer readings are good for PYO and fall sales. Large fruit are going to be soft, generally, before small fruit, and those on the inside of the tree will be softer than those on the outside of the canopy. Choose fruit size that is representable of your crop. Testing small, medium and large fruit is fine as long as you differentiate them in your records and don’t compare one size to another when making harvesting decisions. Use the larger head on the firmness tester for apples and the smaller head for pears. Test both the green side and the blush side of each fruit, and then take the average. Remove only the skin – do not cut into the fruit deeply or your test will be flawed. This works best when done on a hard surface and not when holding the fruit in your hand.

 All of these tests can be done in the field simply, quickly and accurately. Begin testing a couple of weeks before the anticipated beginning of harvest. Keep records and test weekly, more often during harvest to avoid placing fruit into CA – short or long term – that shouldn’t be there. Soft, over-mature in = poor fruit quality coming out.

Storing Honeycrisp

Such a fickle variety to grow and store, makes one wonder why anyone would bother, except that customers want it. Harvesting and storage is important with all varieties but Honeycrisp is abit different because it is susceptible to a wider range of physiological disorders including senescent breakdown, greasiness, bitter pit (hopefully you applied calcium in your cover sprays this summer), soft scald, soggy breakdown and wrinkling.

A great deal of research into harvesting and storage of Honeycrisp has been done by Chris Watkins, Cornell and Jim Mattheis, USDA, Washington State. Their suggestions for success with Honeycrisp are the following:

  1. Make sure the fruit has enough red color at harvest. The background color should be breaking from green to yellow.
  2. Starch conversion should be around 4.5 to 5.0 on the six-point scale.(See the information on starch testing)
  3. Acid level should be fairly high, preferably at least 0.5 percent.
  4. Honeycrisp at 12.5 pounds pressure will retain firmness and texture if handled properly in storage.
  5. There is a difference in how the apples perform in storage, depending on if they’ve been treated with MCP before harvest (Harvista) or after harvest (SmartFresh). Because Harvista tends to delay maturity, it can reduce sensitivity to chilling injury, which has not been seen from a SmartFresh application.
  6. Smart Fresh treatment of air-stored fruit can be as effective as CA storage for at least several months.
  7. It is very important to condition the fruit for 7 days at 50°F before putting into storage at 37° to 39°F to avoid chilling injury and reduce the risk of soft scald. However, low temperatures in the orchard before harvest can also induce these disorders. If the chilling has happened in the field, there is nothing that can be done postharvest to prevent the disorders.
  8. Oxygen level should be 2 to 3 percent. Low oxygen is not necessary because the variety retains its firmness well, and there can be fruit injury from very low levels.
  9. Carbon dioxide level should be between 0.5 and 1.0 percent. Honeycrisp is not as sensitive to carbon-dioxide injury as some other apples

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Useful links

UMass Fruit Advisor:

Scaffolds Fruit Journal:

Network for Environment and Weather Applications (NEWA):

Dr. David Rosenberger's Plant Pathology at the Hudson Valley Lab (including his 2014 Blog)

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UMass Vegetable & Fruit IPM Network (on Facebook,

The next Healthy Fruit (and apple maturity report) will be published on Tuesday, September 9, or thereabouts, 2014. (In two weeks.) As always feel free to get in touch with any member of the UMass Fruit Team ( if you have questions or comments.