Healthy Fruit, Vol. 26, No. 8, May 22, 2018

Jon Clements, Author (unless otherwise noted) and Editor


Current degree day accumulations

Current bud stages

Upcoming pest events

Upcoming meetings

The way I see it




Hawkeye’s corner

Guest article

Facebook Me

Useful links

Thank you sponsors...

Current degree day accumulations

UMass Cold Spring Orchard,

Belchertown, MA


Base 43 BE (NEWA)


Base 50 BE (NEWA)


Current bud stages

Current bud stages. May 22, 2018, UMass Cold Spring Orchard, Belchertown, MA

McIntosh apple

Fruit set


Very late bloom to fruit set

Crispie pear

Fruit set

Redhaven peach

Shuck split

Regina sweet cherry
Very late petal fall - fruit set

Note: this will be the last Current bud stages for 2018!

Upcoming pest events

Coming events

Degree days
(Base 43)


Codling moth 1st flight peak

563 to 991

1st sustained trap catch = biofix set to start DD model for insecticide timing

Lesser appleworm 1st flight peak


Does anyone know if this pest is a problem in MA orchards, or is it taken care of with petal fall sprays?

Oblique-banded leafroller pupae present

601 to 821

Hang pheromone traps to monitor presence/absence?

Pear psylla hardshell nymphs present

493 to 643

Early season pear psylla management should have prevented these; if not, you are looking at season-long battle now with insecticide(s)

Plum curculio oviposition scars present

485 to 589

Monitor for signs of activity during warm, muggy weather; fruit not particularly susceptible until it reaches 7 mm size; be proactive with petal fall insecticide

San Jose scale 1st flight peak

557 to 737

I have never been successful trapping these with pheromone traps; continue to monitor for sign of SJS infestation

Spotted tentiform leafminer leaf mines forming

367 to 641

If present, treatment may be warranted

McIntosh fruit set

508 to 596


Upcoming meetings

From Heather Faubert @ URI:

Come join Sonia Schloemann (UMass) and me at Ward’s Berry Farm, 614 South Main St., Sharon, MA on Thursday May 24, 2018 at 5:30 PM. Guest speaker: Dale Ila Riggs, The Berry Patch in Stephentown, NY, will speak on exclusion netting to protect fruit against spotted wing drosophila and other pests. Sonia Schloemann, UMass Small Fruit Specialist and Heather Faubert, URI, will speak on current blueberry topics such as pruning, nutrition and insect management. Meeting is free with annual dues payment of $40, or $20 for non-RIFGA members. Light dinner will be served. Two hours of pesticide recertification credit available. Registration is not necessary.

From Mary Concklin @ UConn

Twilight Meeting: The CT Pomological Society Annual Summer Twilight meeting will be held on Wednesday, June 13, 2018 at 6 PM. Bishops Orchard, 520 New England Rd, Guilford, CT. RSVP is requested for dinner planning purposes. Email Michaele Williams at or text to 860-304-3506 and include your name and # attending. No cost to you. This is open to everyone. Join us, meet new friends and catch up with old ones. Discussion on pest issues with Dr. Jaime Pinero, UMass Extension’s new fruit entomologist; I will discuss disease issues; Evan Lentz and Casey Lambert, UConn iPiPE interns, will discuss the iPiPE program; staff at Bishops will give a tour of the farm; and more. 2 Pesticide credits will be available.

The way I see it

Jon Clements

Well into fruit set of apples, although there is still some bloom out there! Reminder if you are going to spray carbaryl for fruit thinning, per the label, do not apply when bees or other pollinating insects are active on bloom, i.e., the period around sunrise or sunset (or at night) is best. See example Honeybee Foraging Activity and Potential Wet Residue Exposure chart on Ag-Radar to get the idea...

Last week I attended a fruit thinning meeting in Hudson, NY hosted by Cornell’s Hudson Valley Commercial Horticulture program. Polina Francescatto (Cornell) and Win Cowgill (Rutgers, retired) gave their assessment of apple fruit set and thinning recommendations. In a nutshell, fruit set looks real good, a bloom thinner (NAA or NAD) should have gone on followed by relatively aggressive petal fall and 10 mm thinning (as necessary) with NAD, NAA, carbaryl, or 6-BA (Maxcel, etc.) Dan Donahue (Cornell) summarized their comments in 2018 Hudson Valley Crop Assessment for Thinning and Apple Thinning Suggestions for 2018. Also consider reading Spray Mixing Instructions (for chemical thinners) Considering Tree Row Volume - TRV.

It looks like the upcoming weekend we will be under some apple tree stress as indicated by the carbohydrate balance model, so anytime now will be a good time to apply chemical thinners. Get out there and do your (chemical thinning) job! :-)

Zestar! On 22-May at UMass Orchard


Jaime Pinero

Efficacy of non-pyrethroid insecticides applied against plum curculio and Oriental fruit moth in apple (petal fall) and peach (shuck split), with notes on environmental and health impacts.

The following two tables present the relative efficacy of 13 non-pyrethroid insecticides for petal fall (apple) and shuck split (peach) applications against plum curculio and oriental fruit moth. Information presented on the four columns on the right pertain the potential environmental effects of the pesticides listed using the Environmental Impact Quotient (EIQ) developed by Dr. Joseph Kovach and collaborators (1992).

The EIQ was created to provide growers with data regarding the environmental and health impacts of their pesticide options so they can make better informed decisions regarding their pesticide selection.  

Values listed in the column titled “Field Use EIQ Value” originate from the EIQ value of each insecticide multiplied by the % active ingredient by the label application rate (for the calculations, I only used the low application rates; EIQ values will be higher if the high label rates are used). Values are PER APPLICATION. The higher the Field Use EIQ value, the greater the negative impact of a pesticide. Lower Field Use EIQ values are the least toxic choices.

An equation was developed by Kovach et al. (1992) based on the 3 principal components of agricultural production systems: (1) a farm worker component, (2) a consumer component, and (3) an ecological component. The ecological component is composed of aquatic (i.e., effects on fish) and terrestrial (effects on birds, bees, and beneficial arthropods).

With the EIQ method, comparisons of environmental (consumer, worker, and ecological) impact between pesticides and different pest management programs can be made.  

A video posted by the NY IPM program explains in detail the concept and applications of the EIQ:

1Based on the New England Tree Fruit Management Guide

*Michigan State University

**University of Connecticut

 This is how you can get information presented in the tables for any pesticide (insecticide, herbicide, fungicide) using the EIQ calculator:

1. Go to the NY IPM program - Calculator for Field Use EIQ:

2. On the product label, find the name and % of a.i., and the application rate for the

    crop and pest of interest.

3. Type the information onto the boxes of the calculator (see example of a pyrethroid below).

4.  Get the Field Use EIQ Values.

  Do you have any suggestions for articles on arthropod IPM? Please let me know!      

Contact info:; (413) 545-1031 (campus office); (808) 756-2019 (cell).


Dan Cooley

The End of Primary Scab? The Beginning of Secondary Scab?

As usual at petal fall, primary scab is winding down. How quickly that’s happening depends on who or what is tracking ascospores. The best source, Liz Garofalo’s direct observations, still show spores there and being released. This agrees with the RIMpro estimates that about 10% of ascospores are left to be released. NEWA, on the other hand, estimates all but the last 1% of spores have matured and been released. Based on all this, I think we have the potential for at least one major primary infection over the next week or so. Depending on how the wet weather breaks, it may or may not happen, but the potential is there.

In some orchards, we’re seeing the first scab lesions. Take a look a Liz “Hawkeye” Garofalo’s photos, and these Jon took in our test block at Cold Spring. These infections probably occurred around May 7. Secondary spore production from these earlier infection is happening.

Meanwhile, later primary infections occurred around May 13, May 16 and the largest of the year this past weekend, May 19 - 21. Given temperature trends, any mistakes in control should start to show up over the next few days, and continue to appear into the first week in June. Keep scab protection intact.

Above, a leaf infected with scab showing new lesions, with examples shown by red arrows. Some lesions show the beginnings of dark areas, spores, in the middle of a lighter area. Other infections are still just light areas.

Fire Blight Symptoms

We are seeing the first blossom symptoms from fire blight inoculations made last Monday, May 14. These are artificial infections, because we put high levels of inoculum on the blossoms. They do indicate that conditions have been adequate to lead to fire blight where large amounts of inoculum may have built up naturally. Fortunately, I think cool to downright cold weather at strategic times this season have kept inoculum levels from getting dangerously high. In the same test block, on trees where we used streptomycin one time around inoculation, there are no infections.

Early fire blight on a Jonagold blossom at UMass Cold Spring Orchard on May 22.


Chemical Thinning Recommendations -- Duane Greene

In recent years orchardists have been confronted with challenging weather during the chemical thinning season. This season so far it appears that Mother Nature is looking favorably on apple growers. While there was variable bloom in some orchards, in most cases bloom is heavy enough for a near full crop. We have not experienced catastrophic cold weather, the bloom period was in general good, and we are now entering the time when most growers hope to do the majority of their thinning. The 7 to 14 mm fruit size range is when fruit are most susceptible to thinners. The weather forecast for the next few days is favorable for thinning with daytime high reaching into the 70’s to near 80 F. The carbon balance model will provide appropriate guidance for selecting the time of application as well as suggesting how aggressive the thinning sprays should be.

Currently, the carbon balance is running slightly negative which translates into applying thinners and thinner concentrations as is recommended in the New England Tree Fruit Management Guide.

I have always stressed to growers to look for the first 3 days of favorable weather once the fruit grow to the 6 mm stage. It appears this year that you may have more time. At this point fruit should be growing rapidly; most are at or approaching the 6 mm stage. This is your best opportunity this growing season to do an effective thinning job. Take advantage of this opportunity.

There are no new thinners available this year.   Most of the registered thinners can be used during this time period.

Carbaryl is a perennial grower favorite because it is unlikely to over-thin, it thins over a wide range of fruit sizes. Generally we recommend use at 1 to 2 pints per 100 gal. It serves as a very useful addition to other thinners. When used alone it is useful on easy to thin varieties such as Cortland. When combined with other thinners it provides a safer alternative by allowing the use of a lower rates of stronger thinners ( NAA, Amid-Thin).    

MaxCel is the newest thinner to be registered. It is applied at rates of 1 to 2 quarts per 100 gal of spray. When used alone it is a mild thinner. When it is combined with carbaryl it is considered a strong thinner combination, as strong as growers have available. Experience has shown that MaxCel should be applied when the temperatures are forecast to be at least in the70s for  several days for MaxCel to be effective. It appears that this may be a good year to use MaxCel. MaxCel is usually combined with carbaryl for increased thinning activity. Growers may want to consider the use of MaxCel alone in situations where you are looking for only a moderate thinning but would like to get the size benefit offered by MaxCel. MaxCel is especially useful on Empire. Gala is often a troublesome variety to thin. I suggest that using 1 quart of carbaryl  plus 2 quarts of MaxCel on Gala at the 10 mm stage to be a good combination for thinning and enhancement of fruit size. Similarly, MaxCel plus carbaryl would be a good choice to thin Fuji as well since the use of NAA sometimes leads to the development of pygmy fruit and perhaps smaller fruit size.

NAA thinning activity was discovered in the 1930s and it has been more or less consistently used as a thinner since the 1940s. Growers need little introduction. I strongly recommended using NAA as a bloom and/or petal fall thinner. These sprays can be followed up with a 7-14 mm spray for blocks that show a heavy initial set. Generally rates between 5 and 10 ppm are used but rates up to 15 ppm may be useful on some of the more difficult to thin varieties. NAA plus carbaryl is a good combination where aggressive thinning it desired.

NAD (Amid-Thin) has become a popular thinner recently.  It is a relatively mild thinner when used at 8 oz/100 gal. It can be used at bloom with a follow up application of carbaryl at petal fall or as a petal fall spray with carbaryl. It is usually not recommended for use after petal fall because there are reports, especially on Delicious in the Pacific Northwest, that it can cause pygmy fruit. I suspect that it can be used on other varieties but NAD not been tested recently on modern varieties. It is best at this developmental stage to used MaxCel, NAA or carbaryl alone or in some combination.          

Hawkeye’s corner (notes from the field)

Liz Garofalo

Drum roll please!  

First apple scab lesions of the season have been found (in Mac) in Worcester County, MA.  While no one really likes scab, after counting all those spores, I have to admit, it's just a wee tiny bit gratifying to see disease.  So, scout your hot spots and stay on primary management (the fat lady has not yet sung).  Today’s rain is likely to cause spore release and RIMpro has Belchertown lined up for an “extreme risk” infection event (and predicting another come next Monday).

Black cherry aphid prefers sweet cherry, but isn’t so picky it won’t chew on tart cherries too, and will do a number on the foliage and sooty mold grows on the honeydew secreted on leaves and fruit (yuck).

When thinking about your petal fall insecticide, don’t forget, plum curculio likes cherries too. (Ed. note: FYI Imidan is not labeled for use on sweet cherries!)

Pear psylla nymphs are causing younger leaves to curl due to feeding and hardshell stages have been observed. Save your IGR applications for the next generation of early instar nymphs. If you find you do need to treat for them at this time, Delegate, plus an adjuvant (horticultural oil will do the trick but be careful of mixing with other materials that might cause phytotoxicity) will help knock them back.


Obliquebanded leafroller (OBLR) is still munching its way through the foliage and will soon pupate.  Those shot holes in the leaf are, however, pretty characteristic of gypsy moth, also still lurking but more slowly. (Ed. note: but that is an OBLR larvae you see there. See the May 21, 2018 issue of Scaffolds Fruit Journal if you are interested in and/or worried about OBLR. There will be later treatment options too if you don’t know where you stand, but that relies on putting up pheromone traps and establishing a biofix bases on first sustained trap catch! Sounds like a lot of work, but it is true IPM. IPM does take effort!)

Oriental fruit moth
 eggs are hatching and larvae have begun to burrow into terminal peach shoots (albeit not such a problem in managed peach blocks).

Bind weed, and weed management in general should remain on the priority list.  Need to knock this back before it creeps into the trees and makes it even harder to manage.  This applies to oriental bittersweet and other noxious (and obnoxious) climbing weeds.

Don’t forget to take a look at AgRadar’s honey bee activity chart for pollinator protection decision support!

Guest article

No Guest article this week...

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Useful links

UMass Fruit Advisor:

Scaffolds Fruit Journal:

Network for Environment and Weather Applications (NEWA):

Follow me on Twitter ( and Facebook (

Acimovic Lab at Hudson Valley

Peter Jentsch's Blog

The next Healthy Fruit will be published on or about May 29, 2018. In the meantime, feel free to contact any of the UMass Fruit Team if you have any fruit-related production questions.

Thank you sponsors…

Orchard Equipment and Supply Company, Inc. Conway, Massachusetts

Nourse Farms