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Healthy Fruit - Vol. 26, No. 5, May 1, 2018
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Healthy Fruit, Vol. 26, No. 5, May 1, 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

New England Tree Fruit Management Guide




Hawkeye’s corner

Guest article

Facebook Me

Useful links

Thank you sponsors...

Current degree day accumulations

UMass Cold Spring Orchard,

Belchertown, MA


Base 43 (NEWA)


Base 50 (NEWA)


Current bud stages

Current bud stages. April 30, 2018, UMass Cold Spring Orchard, Belchertown, MA

McIntosh apple

Early tight cluster

Honeycrisp Half-inch
green +

Crispie pear

Swollen bud +

Redhaven peach

green +

Rainier sweet cherry
Bud burst

Upcoming pest events

Coming events

Degree days
(Base 43)


Black stem borer 1st catch

249 to 374

Traps could be made and hung

European red mite egg hatch

231 to 337

Last chance for oil application

Green fruitworm peak catch

96 to 231

If green fruitworm are an issue in your orchard, a pink insecticide is warranted

Green apple aphids present

111 to 265

Don’t worry about it...

Obliquebanded leafroller larvae active

158 to 314

Time to start scouting foliage, however, now is not the optimum time to treat or worry about

Pear psylla 1st egg hatch

174 to 238

Oil is no longer enough to handle these buggers (for now). Young nymphs are your target for insecticides.

Redbanded leafroller 1st flight peak

230 to 378

Good question?

Rosy apple aphid nymphs present

134 to 266

If RAA is a problem in your orchard, a pink insecticide is advised

Spotted tentiform leafminer 1st catch

118 to 218

Not a problem at this stage, but traps might give you an indication if it is going to be a later problem

Spotted tentiform leafminer 1st oviposition

143 to 273

Ditto above

McIntosh half-inch green

150 to 201

Been there already

McIntosh tight cluster

206 to 257

Coming very soon

McIntosh pink

267 to 316

Later this week

Upcoming meetings

Tuesday, May 8 -- Fruit Twilight Meeting, Apex Orchards, Shelburne, MA at 5:30 PM on May 8, 2018. Tim Smith will be our host. We will meet at his new sales room at 225 Peckville Road. Light dinner will be served. Bloom time disease and insect management, fruit thinning will be topics of discussion. Two pesticide recertification credits. Pre-registration is not required but $20 meeting fee for individuals getting pesticide credits will be collected at the door. 

Thursday, May 10 -- Fruit Twilight Meeting, Foppema's Hilltop Orchard, 9 McClellan Road, Wilkinsville (Sutton), MA at 5:30 PM on Thursday, May 10, 2018. In cooperation with Rhode Island Fruit Growers' Association. Ken and Evan Foppema will be our hosts. Light dinner will be served. Bloom time disease and insect management, fruit thinning will be topics of discussion. Two pesticide recertification credits. Pre-registration is not required but $20 meeting fee for individuals getting pesticide credits will be collected at the door.

The way I see it

Jon Clements

Fruit twilight meetings next week, see above. Should be good! Apple fruit thinning will be a major topic of discussion. Should be in full bloom.

Finally things are moving. Expect bloom in apple and peach by the weekend or soon thereafter. Scab infection periods have come and gone, and are coming again. This dry interval a good time to get a fungicide on (again). Don’t underestimate the importance of bloom sprays in stone fruit when it is wet and warm to get a head-start on brown rot control. Watch for fire blight conditions as we come in to apple bloom. Get trees planted during this nice, dry stretch coming up! What else is there…???

New England Tree Fruit Management Guide available online

• The New England Extension tree fruit specialists -- which include myself and Dan Cooley at UMass, Mary Concklin at UConn, Heather Faubert at URI, Terry Bradshaw at UVM, George Hamilton and Alan Eaton at UNH, and Glen Koehler and Renae Moran at UMaine -- have officially launched an online edition of the New England Tree Fruit Management Guide. Note that is it easy to print any of the sections, if you want to have old-school reference, for example, to hang on your spray shed wall. Also, it is quite mobile-friendly so make a home screen shortcut to here: Finally, if you really, really want a printed version, and especially if you have Amazon Prime, search ‘New England Tree Fruit Management Guide’ on Your comments/feedback on this work in progress would be appreciated. How do you get your spray/pesticide information these days?


Jaime Pinero

Be part of our plum curculio on-farm demonstrations in 2018!


On-farm demonstrations serve as one of the most effective Extension education tools. Although some demonstrations may require considerable time and effort, the payback comes when stakeholders more readily adapt IPM practices they perceive to be effective and appropriate under local conditions. Seeing is believing!


In preparation for the plum curculio (PC) season, we are seeking 12-15 orchards where we can conduct some simple but meaningful on-farm demonstrations involving odor-baited trap trees and entomopathogenic nematodes (EPNs). I believe it is time to demonstrate the usefulness of this integrated approach to PC control. Below is the basic approach, which involves no changes to any of your PC control measures, minimal use of your valuable time, and this is at no cost to you!

1. During apple tree bloom, I would like to visit you and select one perimeter-row tree in an orchard area that is (but doesn’t have to be) a PC hotspot. Together, we will deploy one dispenser releasing the PC pheromone (grandisoic acid) and one benzaldehyde dispenser to congregate PCs on that tree (= trap tree).

2. You will manage PC the way you usually do, which includes spraying the trap tree.

3. By the end of June, I will to go back to your orchard. Underneath the trap tree we will place two small cages made of PVC, which will be buried to 5 inches deep. Both cages will receive 100 PC larvae. One cage will receive a known number of Steinernema riobrave (nematode species that was found by Drs. Shapiro and Leskey to be the most effective at killing PC larvae). The second cage will serve as control (no EPNs). After nematode application, a capturing device (trap-top consisting of an inverted cone) will be placed on each PVC cage to capture emerging PC adults.

4. Under the canopy of the same trap tree, we will also deploy two emergence cages (3 ft by 3 ft) on the soil. Known numbers of EPNs will be applied to one cage, and the second cage will serve as control. This will assess in a more realistic way the impact of EPN application with natural densities of PC larvae in these two areas.

5. By late July, I will visit you again. We will record the number of PCs that emerged from each cage, and I will sample fruit from trap trees and from non-trap trees.

6. In both types of situations (i.e., PVC cage and larger emergence cage), we will compare the number of summer-generation PCs that emerge from each treatment. If EPNs are effective, we should get statistically fewer (averaged across all participant orchards) PC adults emerging from EPN-treated cages than from control cages.

7.  That’s it!


If you are interested in participating in this demonstration, please click on the link below.

This will happen rather soon, so please let me know within the next 4-5 days (by May 6th).


The link will open a Google documents window where you can let me know that you would like to participate by providing your name, orchard address, and e-mail address. I will then communicate with you to determine the best day to get to your orchard to deploy BEN+GA.

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

See Guest Article below...


Jon Clements

What does one do with these new planted apple whips? It depends. If growing a conventional central-leader, semi-dwarf orchard, it’s easy -- head them off at waist height. If in a tall-spindle system, as these trees are planted 3 feet apart, you have choices.

Whatever you do, keep watered and fertilized so the trees GROW!!!

Prohexadione-calcium (Pro-Ca), Apogee and Kudos for growth control of apples
(Duane Greene)

Prohexadione-calcium (Pro-Ca) is the growth retardant of choice for use to help control

vegetative growth on apples. For many years we have recommended to make the initial

application at petal fall. While growth retardation was achieved when applied at this timing the

extent of growth control was somewhat limited. The primary reason for this was that when Pro-

Ca was applied shoot growth was occurring very rapidly. Since Pro-Ca requires 10-14 days

before growth control is initiated, up to 25% of the potential growth reduction is missed. When

we tested making the initial application at the pink stage of tree development, growth control was

achieved much earlier and to a much greater extent.

A greater degree of growth control is not achieved by using higher rates of Pro-Ca since

only small differences in growth retardation are noted between a rate of 3 oz/100 gal as

compared with 12 oz/100 gal. In some instances more growth control is achieved than desired

when this early application is used. Rather than adjusting the rate applied it would be preferable

to slightly delay the time of application to nearer bloom or petal fall.

There may be other benefits for making the initial application at pink. Early application

results in earlier retardation of growth. Since terminal growth competes directly with developing

fruit for available calcium, earlier retardation of shoot growth makes it possible to increase the

amount of calcium partitioning into the fruit rather than the shoots. We have noted reduced

bitter pit in Fuji and Cortland as a result of this early application, but it does not happen all of the

time. Recently in an article in Scaffolds it was reported that reduction in bitter pit on Honeycrisp

could be achieved with this early application of Pro-Ca. Since calcium only account for a

portion of the incidences of bitter pit in apples it is our feeling that this treatment may help

reduce this disorder but it may not eliminate it under all conditions every year.

Hawkeye’s corner (notes from the field)

Liz Garofalo

Pear psylla are happily laying eggs all over the pear buds as we speak.  Soon, nymphs will emerge and begin sucking the juices out of green tissue and excreting honeydew all over the place making a mess of your pear trees and providing a substrate for sooty mold.


Winter moth update from Heather Faubert:

Egg hatch looks variable this year, click on the link for Heather’s report.

Gypsy moth egg mass on the tree (left), gypsy moth egg mass up close (right), note the imported parasitic wasp (Ooencyrtus kuvanae) laying her eggs through the protective “hairs” surrounding the eggs (red arrows).  She is only able to reach eggs on the surface of the mass so parasitizes approximately 20% of the eggs she finds.

Close up of O. kuvanae. Identification courtesy of Hannah Broadley and Jeff Boettner from Joe Elkington’s lab.  

Provided this wet weather keeps up, there shouldn’t be too much pressure from gypsy moth as the fungus Entomophaga maimaiga will proliferate under current conditions and infect the larvae, killing them. A Dipel (or other B.t. material), however, on young trees (and blueberries…) will be extra, eco-friendly, insurance against these and other leaf-munching lepidoptera.  

Speaking of current (and near future conditions), it looks to be a gorgeous week, with the chance for a fairly significant scab infection on the way Thursday-Friday.  Interesting though to note that as the week progresses the forecast shows a decreasing likelihood of rain, something to keep an eye on. Provided the wind doesn’t kick up, you have a solid window for scab management Tuesday through Wednesday.  For what it’s worth, I counted 378 mature ascospores (in ten random fields) on the slide taken from the two-fan, field-based spore trap. These spores were deposited during the last rain event, and, there will be that many again ready to go for the next rain event.  Scab season is underway in earnest!


Not to be outdone by scab, fireblight (fresh ooze in the photo) is out and looking for some flower to love…and with temperatures predicted to exceed the magic number 65°, bacterial populations will begin building, just in time for bloom.  

Guest article

Disease Update: Apple Scab, Fire Blight, and Brown Rot This Week

Kari Peter, Asst. Professor, Tree Fruit Pathology, Pennsylvania State University

May 3–5 could be potential infection periods for apple scab and fire blight. Brown rot infection conditions favorable for open peach blossoms this week.

After a very chilly spring, summer conditions are going to explode this week. If the forecast comes to fruition with the high temperatures and rain, disease conditions will also explode very quickly. Bloom is right around the corner, and this could be a banner week for apple scab and fire blight. Peaches and nectarines are finally in full bloom, and brown rot blossom blight is a risk during this warm weather. However, forecasts can change quickly. Consequently, growers are encouraged to keep a very close eye on the weather in their location to determine appropriate actions to mitigate disease.


Late pink through petal fall, use FRAC Group 7 fungicides

As we near bloom, we are also nearing the period where the most number of mature overwintering apple scab spores will be available for dispersal. This is period of time, and through petal fall, growers are encouraged to use fungicides containing the FRAC Group 7 mode of action. Even if dry conditions persist during late pink through petal fall, the FRAC Group 7 products will control for powdery mildew control during this time period. These products include Aprovia, Fontelis, Sercadis, Luna Tranquility, Luna Sensation, Pristine, and Merivon. If disease conditions persist and additional fungicide applications are necessary, rotate the FRAC Group 7 fungicides with FRAC Groups 3 and 9. Four complete sprays (eight half sprays) of fungicides containing the FRAC Group 7 mode of action are permitted per season. This includes both premix FRAC Group 7 fungicides (Luna Tranquility, Luna Sensation, Merivon, Pristine) and the stand-alone FRAC Group 7 fungicides (Aprovia, Fontelis, Sercadis). Some of these products are excellent in rot control later in the season and during postharvest. I typically recommend growers use two complete sprays (4 half sprays) of the FRAC Group 7 fungicides during the early part of the season (pink through petal fall) and use two complete sprays of FRAC Group 7 fungicides (Luna Sensation, Merivon, Pristine) near harvest.

Please remember: if disease conditions for apple scab persist from late pink through petal fall, growers have to shorten their interval when using alternate row middle sprays. Monitor the conditions in your orchard closely during this period.


Preventing a fire blight epidemic

The following information was in the latest Fruit Times that went out on Friday, April 27, 2018, but it bears repeating. Bloom will be occurring this week with the very warm temps in the forecast. Monitor weather conditions closely during bloom: open blossoms, average temperatures >60°F, and wetting events (rain, heavy dew) contribute to the potential for fire blight. Commercial fruit growers are encouraged to remain on guard not only during bloom but during petal fall. Our average temperatures from May 1 through May 5 will be in the upper 60s – 70s (some days, the highs will be in the 80s, lows will be in the 60s). Depending on the varieties, bloom could be fast or linger, based on the cooler temps in the extended forecast after our brief warm up this week.

Here is a plan for growers during bloom and after:

Just a word to the wise: If this year ends up being an exceptionally challenging fire blight year, typically “resistant” varieties will get fire blight if the disease pressure is high enough. Read Apple Disease - Fire Blight for more information and a review for susceptible hosts—which could be lurking near your orchard!

Peaches and Nectarines

Preventing brown rot infections

Blossom infections from the brown rot fungus can occur whenever pistils are exposed, and a favorable climate exists. Infections can occur during any wetting period when temperatures are between 41 and 86°F. However, optimum conditions for infection occur with wetting and temperatures in the mid-70s. We will see those conditions this week. During long wetting periods (several days or more) blossoms can be infected regardless of temperature. Generally, infections that occur when conditions are sub-optimal are less severe. Blossoms and fruitlets will remain susceptible until the pistil desiccates (sometime between petal fall and shuck split). Keep blossoms protected with fungicides for blossom blight. Rotate fungicides by FRAC Group and be sure to tank mix fungicides with a broad spectrum protectant for fungicide resistance management.

Facebook Me

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 8, 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