Healthy Fruit, Vol. 22, No. 16, August 12, 2014

Jon Clements, Editor


Current degree day accumulations

Upcoming pest events


The way I see it



Guest article -- Dissecting the use of harvest management tools for apple growers

The New England Apple Scab Control Practices Survey

Facebook Me

Useful links

Current degree day accumulations

UMass Cold Spring Orchard,
Belchertown, MA
11-Aug, 2014
Base 43 (SkyBit)
Base 50 (NEWA)

Note: this will be the last Current degree day accumulations for 2014.

Upcoming pest events

Coming events
Degree days (Base 43)
Codling moth 2nd flight peak
Lesser appleworm 2nd flight peak
Obliquebanded leafroller 2nd flight peak
Redbanded leafroller 2nd flight subsides
Spotted tentiform leafminer 3rd flight peak
Apple maggot flight peak


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

At the UMass Orchard we are picking Redhaven and PF-14 Jersey peaches (among others). Risingstar have all been picked. Quality (flavor and size) are good, and yield is surprisingly good (but not for all varieties). Rainfall has been adequate, but the heavy rain today (Wednesday, August 13) is a mixed blessing -- we could use a litte rain, but: brown rot is rampant on susceptible peach varieties, particularly those not adquately protected with fungicide; the rain is going to necessitate covering up stone fruit (for brown rot) and apple (for sooty blotch/flyspeck and rots) with fungicide (insecticide coverage -- apple maggot fly -- may need to be re-applied as well); and flash flooding may be a problem for some.

I expect the real apple harvest will commence on time, that is during the first week in September. Paulared and Zestar! will be picked the last week in August. Please see the article on assessing apple maturity using the starch-iodine (SI) index. If anyone needs SI test solution, let me know. Note that from AgRadar above, "Begin measuring actual McIntosh starch-iodine no later than Friday, August 29."

Otherwise, it's fairly quiet although I have had reports of high apple maggot fly activity and possible Brown Marmorated Stink Bug (BMSB) damage in/to Gingergold apples. Be weary -- I would appreciate any reports of suspect BMSB activity. Well, maybe "appreciate" is the wrong word, but I certainly want to make note of it! Oh, and we have caught Spotted-Wing Drosophila in traps(s) at the UMass Orchard...


Jon Clements

See Upcoming Pest Events, AgRadar, and Guest Article below for current pest status.


It's still not too late (but getting there) to take leaf samples for nutrient analysis -- each and every block by variety should be sampled every few years (within reason). You can't possibly put together a good nutrient program without leaf analysis results every few years. Forms and more information from the UMass Soil and Plant Tissue Testing Laboratory here.

Calcium sprays to apple should be ongoing. See: Foliar Calcium Sprays for Apples for all you need to know.   

Guest Article

Dissecting the use of harvest management tools for apple growers (2013)

Phil Schwallier and Amy-Irish Brown, Michigan State University Extension

Re-printed from MSUE News (Fruits & Nuts)

Harvest management is a primary reason growers use ReTain on apples. However, there are many other benefits that ReTain can offer apple growers. The ReTain effect on improving storage quality is a major desire for shippers and processors. ReTain stops the production of ethylene in the apple fruit and thus delays maturity and lengthens shelf life. Michigan State University Extension’s best recommendation is to use ReTain at full rate split into two sprays at 30 and 14 days before harvest. Add NAA at 20 ppm with the 14-day before harvest application. This will give you maximum stop drop and good harvest management. Remember, some sensitive varieties like Gala and Jonagold should only receive a seasonal rate of half the full rate.

ReTain will delay apple maturity, thus allowing harvest management of large blocks of one variety. ReTain is also dose-dependent, that is, a full rate will give maximum delay of maturity, say, 14 days. Half rate will only give half of the delay of maturity, say, seven days. This allows growers to better plan harvest. For example, one-third of your Galas could be treated with a half rate of ReTain and one-third of your Galas could be treated with one-quarter rate and thus the grower could harvest untreated Galas one week, the one-quarter rate treated Galas the next week, and the half rate treated Galas the third week. All the Galas would be picked at prime maturity over a three-week period.

ReTain is dose-dependent and time-dependent. The standard recommendation of ReTain use is to apply full rate at 30 DBH (days before harvest). However, a grower can apply the ReTain 14 DBH or even in split applications. There can be some complications from delaying ReTain applications closer to harvest, but it also allows for more grower flexibility of ReTain use. Later applications of ReTain tend to have less impact on red color development and allow for combinations with NAA. Typically, NAA is applied about 14 DBH of any variety. Waiting to apply ReTain 14 DBH allows growers to make one application of the combination ReTain + NAA instead of two trips (ReTain at 30 DBH followed by NAA at 14 DBH).

Other major benefits of ReTain include its stop drop impact on apples. ReTain stops ethylene production, which stops the ethylene ripening effect and, thus, dropping fruit – a ripening effect. NAA does this as well, but by a different effect, that is delaying the formation of the fruit abscission zone. Unfortunately, NAA also turns on ethylene which, in turn, will ripen fruit and after NAA wears off, fruit drop will be enhanced. ReTain, however, will eliminate the NAA-induced ethylene. So in using the combination of ReTain + NAA you get the best of both worlds, improved stop drop from both materials and ReTain’s control of the NAA induced ethylene ripening.

ReTain also reduces watercore, greasiness, cracking and improves fruit size. Shippers and processors like the improved storage quality and longer shelf life of ReTain-treated fruit, especially the greater fruit firmness from ReTain. The combination of ReTain + NAA is an improvement over using either material alone. We still have to work out what is the lower rate of ReTain that will work with NAA and more work on the timing of each material.

Overall ReTain + NAA has performed well in the past four years of trials on all varieties.

Ed. notes (J. Clements)

For more comprehensive information and research results from Schwallier and Irish-Brown, see ReTain and NAA recommendations for 2013

Minimum full rate ReTain use is recommended for McIntosh (and other McIntosh-type apples), however, Honeycrisp and Gala color and maturity development are very sensitive to ReTain -- use of no more than half-rate is recommended on these varieties. Otherwise, color and flavor development will be compromised.

Keep these pointers (direct from the label) in mind when applying ReTain:

If you have any questions about the use of ReTain apple, don't hesitate to call or e-mail me. (413-478-7219,

The New England Apple Scab Control Practices Survey

If you have not already filled out the Apple Scab Control Pracices Survey, it's not too late:

You are invited to participate in a research project about your scab management practices.  This survey is part of a larger research project being conducted in New England with Dan Cooley, Arthur Tuttle, and Jon Clements at the University of Massachusetts, Cheryl Smith, Bill MacHardy, George Hamilton at the University of New Hampshire, and Glen Koehler and Renae Moran at the University of Maine.  The purpose of this survey is to collect information on changes that have occurred in the last two years in grower practices for scab control.  Your previous responses have helped Extension specialists develop tools for apple growers to manage apple scab.  We are conducting this research project in New England states, and will summarize the results in a report for growers this summer.

This is a follow-up survey to the one that was sent two years ago.  It has the same 10 questions and will take approximately 7 minutes of your time. 

Here is a link to the survey: 

Thanks for your participation!

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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)

Follow me on Twitter ( and Facebook (

UMass Vegetable & Fruit IPM Network (on Facebook,

The next Healthy Fruit (and apple maturity report) will be published on Tuesday, August 26, 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.