Today's newsletter reports average king fruitlet diameters on varieties ranging from 15 mm to 22 mm with the results of chemical thinners still under observation. Please note that symptoms of early blossom blight infections are now being reported in pears. Also, for newly planted trees that might be in bloom there is a fire blight blossom blight risk approaching this week. Information is shared on codling moth treatment timings and summer miticides are discussed. With the summer solstice just around the corner there are a few horticulture reminders. Thanks to the ongoing commitment of the Orchard Outlook Committee members.

Bud Development

Apple Buds

An early region on Middle Dyke Road in the Kentville area is monitored to guide this newsletter. Yesterday on June 16, ten king fruitlets of each of the following varieties were measured to get a rough average (size of king fruitlets guides thinner timing). The Idared measured 22.2 mm, Honeycrisp 19.4 mm, and Ambrosia 16.0 mm (Figure 2).

Similar measurements were taken in Melvern Square and South Berwick, including Gala at 15 mm. Likewise, committee member Harrison Wright contributed measurements from Pereaux as Gravenstein 21 mm, Idared 17 mm, Cortland 16 mm, and Honeycrisp 18 mm.

Over the past week, Idared grew 1 mm/day, Honeycrisp grew 0.9 mm/day, and Ambrosia grew 0.9 mm/day. Typically fruitlets grow about 1 mm each day in average temperatures. Compared with last year, fruitlets are about 1-2 mm larger so they are about 1-2 days ahead.

The results of chemical thinning are still under evaluation. The only chemical thinning that may be possible now is rescue thinning. Refer to the thinning section later in the newsletter for more information.

Figure 2: Fruit size in an early region on Middle Dyke Road in Kentville on June 16. Shown from left to right: Idared (22.2 mm), Honeycrisp (19.4 mm), Ambrosia (16.0 mm). The king fruitlet is measured to represent fruit stage for thinning.

Diseases

Apple – Scab

Recommendations:

According to the model, total seasonal ascospores matured to 100% on Saturday, June 7 and the wetting event would have released the final primary spores. Models are not completely accurate so wait 2 weeks after ascospores are depleted and when you can assess your incidence of primary apple scab infections. Decisions about whether to lengthen fungicide intervals can be made on June 22.
Product options at this time of the year:

Captan may be used as long as it is not applied within 7-14 days of an oil such as Agral 90 (worse if applied after oil that preconditions leaves). The REI for hand thinning fruit in high-density systems is 15 days and in low-density systems it is 24 days. The product has activity on summer diseases that is ideal. For high density, do not use more than 10 applications per year and for low density do not use more than 2 applications per year. Remember, if using SHARDA CAPTAN 48 the rate equivalent to other captan products is 5 L/ha (2.4 kg of active ingredient). Please note that this liquid format might improve uptake and also increase the risk of leaf injury.
Allegro/Vantana/Downforce may be applied as long as oil has not been applied within 3 days (including Fontelis and Agral 90). The REI is short at 24 hrs.
Migiwa is registered for scab control and it has a short REI of 12 hours. Just be sure to use the high rate of 220 mL/ha so that the powdery mildew that is present isn't exposed to a sublethal dose at the low rate. We want to preserve this product efficacy for powdery mildew.
Do not apply: Folpan/Follow and Syllit should NOT be applied between tight cluster and 30 days after petal fall to avoid fruit russeting.
Buran may be considered. But remember that the product is registered for only suppression of apple scab and must be used post-infection only. Summer disease control is not likely strong.
Note that single site products in group 3 are not expected to provide control of apple scab due to resistance. For other single site products, check the label for rates required for apple scab control because for Luna Tranquility the high rate is needed unless it is tank mixed with another product for scab control. All single site products should be tank mixed with a half rate of a group M product for resistance management.
Several of the single site products do not have activity on scab after petal fall (fruit scab). Such products include Fullback, Nova, Cevya, Aprovia, Sercadis, Excalia, Scala, and Vangard.

Apple – Powdery Mildew

Powdery mildew infections can be expected when conditions are warm (10-25°C), humid and dry.

Recommendations:

Protection may continue on young plantings because severe infections can reduce shoot growth, which is most concerning for young, non-bearing orchards. Pay particular attention to susceptible and high-value varieties such as Honeycrisp and Gala. Product reapplication intervals can vary from 7-14 days.
The forecast for this week would suggest that this week offers the opportunity for infections to happen during the warm and dry weather.
New products registered this year for apple powdery mildew with unique chemical groups include:

Migiwa group 52, control of scab, short REI of 12 hrs, max 3 apps total.
Gatten group U13, no activity on scab, short REI of 12 hrs, max 4 apps total.
Property group 50, no activity on scab, short REI of 12 hrs, max 4 apps total.

Some notes about industry-standard products:

The chemical group 3 products Nova/Fullback are very effective. Fullback and Nova are systemic and given a long drying period of 24 hrs they should be well-absorbed into the plant. (Fullback and Nova will not provide scab protection due to industry-wide fungicide resistance.)
If you're using Luna Tranquility for powdery mildew, concurrent activity for scab control is only provided at the high rate.
There is no expected resistance to chemical group 3 and 7 products so the products are expected to be effective.
There is industry resistance to group 11 products such as Flint so it should not be used for powdery mildew management.

To avoid resistance development, do not use any products with powdery mildew activity more than two times consecutively (without rotating to another chemical group with powdery mildew activity).

Fire Blight Prevention

Recommendations:

Pruning and training practices should be done on dry and sunny days, especially in high risk blocks. Wounds can take about 2 days to heal. Do not work in trees when they are wet from dew.
Do not pinch flowers on young trees in wet weather even if the bacterial EIP is low. Pinching causes open wounds like a trauma event and bacteria are transported to wounds in wet weather.

Apple – Fire Blight Blossom Blight

Current and Forecast Blossom Blight Risk

The risk of bacterial growth on flowers is below threshold for today but it is forecast to approach and exceed the threshold soon.

On Wednesday, June 18 the EIP is forecast to reach 85.
On Thursday, June 19 the EIP is forecast to exceed the 100 threshold indicating high bacterial populations. Note the risk of rain on Thursday that could trigger infection.
North Medford and Windsor should be prepared for earlier infection risk on Wednesday (if wetting occurs).
An alert email will be sent tomorrow with updated predictions.
Blossoms may be removed for as long as rain is not in the near future.
If Kasumin is planned then it must be applied before the rain.
Do not underestimate the risk of infections on late flowers. By the time of late flowers there is already plenty of bacteria established throughout the environment.

Industry alerts will continue while there are blossoms in young plantings.

Please note: If you're using PomeBlight there is an issue with how it is recording daily maximum temperature after 4 PM. We are aware of the issue but will need to wait until after fire blight season to address it. For ease of use, we recommend that you check the forecast before 4 PM. If you check the model after 4 PM then you will need to manually enter the maximum temperature for the day using the value from your Davis weather station.

Fire Blight - Infection Management

Signs of early blossom blight infections were reported in pears beginning around June 16. Even though it might be only early infections showing, there was the potential for significant incidence.

Recommendations:

As soon as you find fire blight infections, an application of Apogee/Kudos (prohexadione calcium) can help to suppress the progression of infection that buys you time for cutting it out. Use a lower rate if trees have not filled their space or the full rate if tree growth is not an issue.
Do not break off branches with fire blight infections as you navigate the orchard. Research shows that the bacteria becomes systemic in the tree because branches are not adequately removed. There are then a high number of new infections and significantly more canker tissue and cankers on structural wood.
Prune out fire blight infections on young trees in the current year, don't wait for winter.
Remove fire blight strikes at least 2-4 ft below active infections to remove the leading edge of the bacteria. The younger the tree, the deeper the cut. Being aggressive at the first sign of symptoms will help prevent the re-occurrence of symptoms and the need for continuous cutting back. Repeat tree inspections.
If you feel confident that you can monitor the formation of a canker on a stub cut for later removal, then a stub cut may be appropriate. A 4-inch stub cut causes a canker to form on the stub before reaching structural wood like the leader of the tree. However, do not forget to remove the stub because otherwise the canker will serve as a source of bacteria. Mark the tree for revisiting.

Apple – Black Rot

Recommendations:

Based on our limited knowledge, the highest risk of infections is theoretically between petal fall and 4-6 weeks later.

A 10 hr wetting period at 16°C to 32°C allows infection.
The optimum temperature for infection is 20°C to 24°C.
There are few management options to cover such a long risk period. Captan has activity but note the REI for orchard activities. Merivon has activity but this group 7 + 11 product should not be used more than 4 times each year. Folpan has activity but should not be applied until 30 days after petal fall to avoid russet. We do not have a model for black rot infection but protection would need to be targeted prior to wetting and ideal weather conditions.

The fruit cuticle is sensitive to damage at this stage and if damaged can allow entry of the black rot fungus. Be cautious with spray mixtures (calcium, foliar nutrients) that could create an entry point for the pathogen.

Apple - Brooks Spot

Brooks spot is caused by a fungus that creates sunken, dark green lesions on the fruit. It is a minor disease that has been an issue on Honeycrisp in the past. The symptoms of Brooks Spot can resemble lenticel breakdown and bitter pit which are also common on Honeycrisp. Include a product for cover sprays that is labelled for brooks spot such as Inspire Super and Aprovia Top (or Folpan 30 days after petal fall).

Apple - Flyspeck and Sooty Blotch

These summer diseases develop on the surface of the fruit in midsummer until harvest. They are caused by fungi that overwinter in dead twigs and the fungi tend to cause more infections under conditions of moderate temperature, high humidity and rainfall. Usually this disease is associated with lack of fungicide residues from long fungicide reapplication intervals. Include a product for cover sprays that is labelled for flyspeck and sooty blotch such as Captan, Maestro, Inspire Super, Aprovia Top, Cevya, Allegro, Pristine, and Merivon (or Folpan 30 days after petal fall).

Insects

Apple and Pear: Codling Moth

Degree Day and Treatment Timing Predictions

The biofix dates for this season are June 10 for early regions and June 14 for late regions determined by Erika Bent, APM.

Suzanne Blatt, AAFC, has run Jeff Franklin's calculations for the degree day model today to predict when degree day thresholds will be met for treatments. The models were run on Tuesday, June 16 with a degree day threshold of 10 degrees (C) using Kentville weather station data.

As of June 16, the degree day accumulation for the early biofix date is 35.7 degree days Celsius. The forecast to the end of June 20 is 69.7 degree days Celsius. Stay tuned for updates and for treatment timing options see below.

Codling Moth Treatment with Rimon
Timing: The treatment timing for Rimon is 80 degree days Celsius from biofix to target eggs before they hatch.

Codling Moth Treatment with Egg Hatch Products
Products: Assail, Delegate, Intrepid, Altacor, and Exirel
Timing: The treatment timing for egg hatch products is 100 degree days Celsius from biofix.

Codling Moth Treatment with Organophosphate
Product: Imidan

Caution: All hand thinning activities must be completed prior to application. No hand thinning can occur on trees treated with Imidan.
Timing: Control of codling moth with Imidan is typically slightly later at 140 degree days after biofix.

Apple - Sucking Insects

Aphids: Monitor in young trees and nursery plantings where feeding can disrupt shoot growth. If leaves are curling high water volumes are needed for effectiveness.
Mites: European red mite, two spotted spider mite and apple rust mite are the prominent species that affect apple trees. Although not directly damaging to the fruit, these mites in all their motile life stages can drain the nutrients from the trees and dramatically degrade fruit quality.

Mite counts are most accurate by using a specialized machine for brushing. Growers without a crop consultant can use the process of determining the presence or absence of mites on 5 leaves of 4 trees per block. The threshold depends on the sample time and number of leaves so contact me for more details.
In a hot and dry year, mite populations can double in 7-10 days.
Good spray coverage is critical.
Mites have many generations per year and therefore have a high potential to develop resistance. For resistance management, it is critical to rotate miticide classes.

European red mite: Red mite populations can begin to increase and cause damage in the summer.

Mid-June is the first sampling period. New eggs hatch in June and nymphs are present at a relatively uniform life stage. By mid-July there is an overlap of generations and all life stages (eggs, nymphs and adults) are present.
If eggs are numerous then products with ovicidal activity should be used such as Nealta or Envidor.
If mites are motile/active then products with motile activity should be used such as Acramite, Magister, Nexter, Nealta, Envidor or Kanemite.
AgriMek and Minecto Pro are applied early for early absorption and they have long residual activity (8-12 weeks) to control motile stages after they hatch.
Envidor is slow acting so it requires early intervention.
Acramite, Kanemite, Nealta, and Nexter provide quick knockdown.

Two-spotted spider mite: Are expected to be present in mid-June as well and may be included in the red mite count for threshold levels.
Rust mite: Typically present in mid-July. A microscope is needed for identification. Contact me for thresholds. All miticides are effective on European red mite and two-spotted spider mite but only products Nexter, Envidor, and Magister provide control of rust mite.

Pear Insects

Pear Psylla: Refer to the management guide for product options.
Pear rust mite: Pear rust mite can go unnoticed until heavy russeting extending from the base to the top of the fruit. Growers that apply Agri-mek for pear psylla control would also obtain pear rust mite control. Nexter or Envidor would be other options for pear rust mite control.

Thinning

Crop Load

Crop load so far appears to be good and better than expected, and thinning was required. Fruit drop from early chemical thinners is ongoing and the later applied chemical thinners are only in early stages of drop. It can still be very challenging to determine which fruit will stay or drop but some size differentiation is becoming more apparent.

The clusters in Figure 3 were monitored over time at an early site to provide an example. These clusters are located in the tree bottom so likely experienced heavier drop. Fruit drop occurred on these clusters recently and some fruit were easily dislodged by running a hand through the clusters. In hindsight, thinning conditions were conducive to good thinning activity and time will tell the outcome with hopes that some of the heavily set clusters will thin.

Figure 3: The same clusters were observed over a two-week period. The top photos are Cluster 1 where the laterals that appeared strong only one week ago have shed. The bottom photos are Cluster 2 where the king fruit grew the most and the other laterals are shed.

Research has demonstrated that there is a recommended crop load associated with trunk diameters of young apple trees in high density systems. Our ideal crop load for Honeycrisp based on local research is 6 fruit/cm². Our ideal crop load for Gala is 6 fruit/cm² or if you would like larger fruit then 4 fruit/cm². Refer to Table 2 to see how the recommended crop load relates to tree trunk diameter measured about 10 cm above the graft union. For large, old trees, measuring the size of typical limbs might be more appropriate.

Table 2: The recommended crop load for young high density apple trees based on trunk diameter. Honeycrisp and Gala trees can have 6 fruit/cm² or if you would like larger Gala fruit then 4 fruit/cm². For the chosen column, note how many fruit can be cropped based on trunk diameter. For example, at 6 fruit/cm² , a Honeycrisp tree with a 2" trunk diameter would have 122 fruit.

Apple Fruitlet Thinning

Please note that the timing of chemical thinning is based on the average size of the king fruitlet and that all varieties are likely now beyond the typical thinning window of 7 to 12 mm.

Recommendations:

If rescue thinning is necessary, Accede treatments may be applied to high value varieties this week when they are expected to measure 15-25 mm. Earlier treatments are expected to be most effective.
Remember that you can adjust your spray pattern based on fruit set on the top versus bottom of the tree. Usually late in the thinning window the target is excess fruit set in the top of the tree so you may direct your spray.

Defruiting Young Trees

Defruiting young trees can be accomplished with a combination of Sevin XLR at 2.5 L plus Maxcel/Cilis Plus at 5.0 L per 1000 L of water applied using dilute nozzles to the point of drip. A few litres of oil (10.6 L/1000 L water) can also be added as a spreader sticker to this combination unless the variety is sensitive to oil (avoid Gala, Ambrosia, Golden Delicious, Red Delicious).

This mixture should cover more than an acre of young trees.
Apply from petal fall until 8-10 mm. A second application can be done before 18 mm if additional thinning is needed. A second application will likely still miss some fruit so consider that hand thinning may still be required anyway.
This week's heat would aid in the defruiting activity.

Choosing to use Fruitone (NAA) in this mixture instead of MaxCel will result in chemical pinch at the terminal bud that stunts growth.
Using currently available products, the amount of product that would be needed to completely defruit trees in our climate would likely negatively affect tree growth. Therefore, expect that hand thinning will still be required.

Pear Hand Thinning

On mature trees, if the total crop load is high then reduce the number of fruit per cluster to 1 or 2. During years of light fruit set, leaving 2-3 fruit per cluster will still produce good sized fruit. Space clusters 12-15 cm apart.

Peach Hand Thinning

Hand thin early-maturing varieties first for increasing the chances of fruit sizing.
Start thinning after natural drop is clear.
Space fruit clusters about 15 cm apart.

Horticulture

Solstice Reminders

Top dressing is not recommended after the end of June. Late release and uptake will prevent trees from hardening off before the winter.
Around July the trees are storing reserves in the roots for next year’s growth. When they are storing reserves, late glyphosate applications can be damaging if taken up by root suckers and transported to the root system. Avoid the risk by avoiding glyphosate applications after the end of June.

Suckers

Suckers are becoming quite strong by now and would be resistant to sucker control using contact herbicides if suckers are taller than a few inches in height. Remove woody suckers by cutting or ripping to avoid resource competition, the risk of systemic herbicide uptake, harbouring pests like fire blight shoot blight.
If suckers are more prevalent because of exposed roots due to frost heaving, try to hill the soil to cover the roots.

Mowing

Keeping the orchard floor cover mowed pre-bloom will minimize dandelion flowers that attract bees, which increases the safety of insecticide applications.
Mowing and herbicide strips help to prevent issues with two-spotted spider mite (John Michael Hardman).

Pruning and Training

Select strong terminals on young trees and remove competing terminals to single the tops if there are no re-entry intervals active.
Pruning and training practices should be done on dry and sunny days, especially in blocks with high risk of fire blight. Wounds can take about 2 days to heal. Do not work in trees when they are wet from dew.
Ensure that deer fencing is installed as soon as possible to protect new growth on young trees. Prior to deer fencing, the product Bobbex may be used as a deer repellent but it requires frequent application to new growth and after rainfall.
Newly planted trees should be pruned for tree structure and supported as early as possible after planting. Prioritize trees that are known to be brittle at the union, including many of the new Geneva rootstocks (G.11, G.41, G.16 etc).

Weed Management

If you applied a residual herbicide about 6-8 weeks ago (end of April) then you are likely due for reapplication.

For young trees (1-2 yrs), a good option could be Simazine and Dual II Magnum with Reglone for burndown.
In established trees (>3 years), a good option is Alion and Ignite when conditions are dry and hot before an upcoming rain.

If using glyphosate alone, consider coarse droplets and low pressure to reduce drift. By the approaching summer solstice, glyphosate applications become more risky.
When burndown products are needed, consider that Reglone works in cool and cloudy conditions whereas Ignite requires warm and sunny conditions. Also, applying Ignite when leaves are wet is ineffective.
In young plantings, weed control is essential. Local research showed that by year 4, a weedy planting was 39% the trunk cross sectional area of a hoed comparison.

Nursery Trees

Treat for tarnished plant bug and green aphids.
Remove rootstock leaves when they are tender and before shoots become woody.
For bench grafts, leave some shoots on the rootstock to feed the scion as the callus tissue develops. Locally, rootstock leaves have been stripped when the scion has 8-10 leaves. Early in the season, leave at least an extra scion leader for insurance.
Remember the importance of weed control in nurseries. Management practices now will impact the outcome of the final tree. Encourage the growing point to be successful!

Cover Crops

Perennia has a series of videos about cover crops by Sonny Murray and Rosalie Gillis-Madden that can be accessed from our website.
Summer grasses such as pearl millet and sorghum-sudangrass that have been growing in popularity lately can be planted from mid-June until early August.

Events and Notices

Save the Date - Growing Good Growers June 26

The Growing Good Growers tailgate session will be held on Thursday, June 26 @ 11am. The topic is apple maggot. Stay tuned for details.

Save the Date - NSFGA Summer Tour August 6

The 2025 NSFGA Summer Orchard tour will be held on Wednesday, August 6th, 2025. This year NSFGA is continuing to offer the evening portion of the tour and hosting a barbecue dinner, with families welcome to join for an evening meal! A bus will be provided, seats are limited.

Events like this are only possible through sponsorship! NSFGA has announced that sponsorship opportunities are now available.

Pest Management Guide

We offer printable PDFs of the guides from our website:

Online pest guides are also available without login (https://www.perennia.ca/pest-guides/) and with login on your Perennia account (https://www.farmdatatools.perennia.ca/). Using the online tool you can filter for organic and conventional options, search for key information, and sort based on information of interest.

This Orchard Outlook has been published with the input of the Orchard Outlook Committee including this week's participants: Harrison Wright, Suzanne Blatt, Larry Lutz, Danny Davison, Ian Willick, Joan Hebb, Heather Rand, Kari Brown, Keith Fuller, and Shawkat Ali.

Edited by Michelle Cortens, Tree Fruit Specialist
Perennia Food and Agriculture Corp.

Pages

Orchard Outlook Newsletter Vol. 25, No 10

Tuesday, June 17, 2025

Table of Contents:

Bud Development

Apple Buds

Diseases

Apple – Scab

Recommendations:

Apple – Powdery Mildew

Recommendations:

Fire Blight Prevention

Recommendations:

Apple – Fire Blight Blossom Blight

Fire Blight - Infection Management

Recommendations:

Apple – Black Rot

Recommendations:

Apple - Brooks Spot

Apple - Flyspeck and Sooty Blotch

Insects

Apple and Pear: Codling Moth

Apple - Sucking Insects

Pear Insects

Thinning

Crop Load

Apple Fruitlet Thinning

Recommendations:

Defruiting Young Trees

Pear Hand Thinning

Peach Hand Thinning

Horticulture

Solstice Reminders

Suckers

Mowing

Pruning and Training

Weed Management

Nursery Trees

Cover Crops

Events and Notices

Save the Date - Growing Good Growers June 26

Save the Date - NSFGA Summer Tour August 6

Pest Management Guide

Blog Archive