This week’s newsletter highlights recent apple scab infection periods driven by multiple wetting events and notes that this is a high-risk time of year, with elevated spore pressure. It's now likely for fire blight ooze to appear on overwintering cankers, making it important to carry out any activities that may wound trees only during dry conditions. With stone fruit moving into bloom amid wet weather, timely fungicide applications for brown rot are recommended at pink to early bloom and again at full bloom. European red mite egg hatch has not yet begun, but is expected soon. Meanwhile, the window for managing pre-bloom insects is approaching, beginning as buds separate when sprays can better penetrate flower clusters. As always, we extend our sincere thanks to the Orchard Outlook Committee members for their ongoing dedication and valuable contributions.

Weather

2026 Degree Day Accumulations

Over the past week, degree day accumulation shifted from below average to above average due to several very warm days. As a result, cumulative degree days have now surpassed both the 5- and 10-year averages (Figure 1). This rapid increase in heat places this season among the warmer seasons observed in recent years.

Heat accumulation is slightly lower than last year, putting development about half a week behind relative to a warm season.

Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to May 11 for the past 17 seasons. Provided by Harrison Wright (AAFC Plant Physiology).

For the following comparisons, please note that early in the season only a few warm events contribute significantly to the accumulated degree days. Trends can change quickly.

Approximately 11% more plant development heat units compared to the 5-year average, and 18% more compared to the 10-year average.
Approximately 10% less plant development heat units compared to 2025, and 24% more compared with 2024.
Approximately 26% more insect development heat units compared to the 5-year average, and 27% more compared to the 10-year average.

Precipitation

We wished for rain, and here it is! Harrison Wright shares a precipitation update that Kentville is now at a total of 76 mm for May, which is the 25 year average for this month for Kentville. At only half way through the month, we may soon surpass the monthly average.

Bud Development

Apple Buds

An early region on Middle Dyke Road in the Kentville area is monitored to guide this newsletter. After a slow start to the season the past week contributed a flush of new growth - wow! Yesterday on May 11, the Idared buds were at bud separation/first pink, Honeycrisp was at tight cluster and Ambrosia was at early tight cluster (Figure 2). Over the past cool week, buds grew about 1.5 growth stages.

Figure 2: Bud development in an early region on Middle Dyke Road in Kentville on May 11. Shown from left to right: Idared, Honeycrisp, Ambrosia.

Pear and Stone Fruit Buds

Yesterday on May 11 at an early region in Greenwich, the pear buds were at tight cluster. Peach/nectarine was at early to full bloom depending on the variety, and European plum was at early bloom (Figure 3). Orchard Outlook committee members also report that sweet cherry in Kentville is at early bloom and Japanese plum in Pereau is at 50% bloom.

Figure 3: Bud development on May 11. Top photos: An early region in Greenwich with pear, peach/nectarine, and European plum (from left to right). Bottom left: Sweet cherry at the Kentville Research and Development Centre by Suzanne Blatt. Bottom right: Japanese plum in Pereau by Harrison Wright.

Hazelnut Buds

Ian Willick at AAFC has offered to share updates on hazelnut trees from his team's ongoing research project at the Kentville Research and Development Centre. The trees were planted last year in 2025 and they are hybrid hazelnuts with resistance to eastern filbert blight. The varieties are all commercially available and they are NY Hazel, Grimo, Dermis, Slate, Northern, and Gene. They were chosen based on pollination compatibility and cold hardiness assessments out of Ontario.

Figure 4: Hazelnut bud development on May 11. The female ovary enlargement is occurring (left) after fertilization by the male catkins (right). Photos from April 27th 2026 courtesy of Emma Adams and Ian Willick.

Diseases

Apple – Scab

Table 1: Apple scab infection events in Kentville from May 6 to May 12, based on the Modified Mills Table.

- For a high inoculum orchard, a significant number of spores can be released during darkness, so begin calculating leaf wetting regardless of the time of day when the wetting event started. An orchard is considered to have a high inoculum load if last season it had 100 or more scabby leaves observed over 600 shoots.
-Assuming a green tip date of April 19. Please use this as a guide because microclimates will cause conditions to vary on individual farms.
Note: The environmental conditions for an infection are listed in the Modified Mills Table.

Currently ongoing: Rain started overnight with most spore release expected at sunrise. At a forecast average temperature of 7.8C, leaf wetting for 16 hours or longer would trigger infection. Cumulative ascospore maturity 35.8% with 7.0% spore discharge since last wetting event.

Recommendations:

Now is not the time to take risks given the risk of high spore release. Over the past week there has been plenty of new tissue exposed and some product wash off from rain events depending on the date of your last fungicide application. Reapply a protectant fungicide on a 5-7 day interval, using the shorter interval after wet weather (cumulative 1-2” rain) or rapid tissue growth.
According to the current forecast, the next infection could occur this coming Friday.

By Friday, ascospore maturity is forecast to reach 49.1% (13.3% discharge since the last rain).
At an average forecast temperature of 12.5°C, an infection would occur after 11 hours of leaf wetness.
Ascospores are maturing at a rate of 4-6% per day, where higher rates occur on warm days.

Folpan/Follow should NOT be applied between tight cluster and 30 days after petal fall to avoid fruit russeting.
If you used oil for European Red Mite control, Captan should be avoided for 7-14 days after an oil application.
Pears: For pear scab, Allegro and mancozeb are not registered uses. Captan may be used 2 times for low density and 10 times for high density. Note that for pears, Scala and Luna Tranquility have a 72 day preharvest interval. Products are listed in the Pear Pest Management Guide.

Apple – Powdery Mildew

Typically, conidia are released around the tight cluster stage. Powdery mildew infections can be expected when conditions are warm (10-25°C), humid and dry. Signs of overwintering powdery mildew infections are visible and they carry the inoculum for this year's new infections.

Recommendations:

A program with two pre-bloom and one post-bloom fungicide for control of powdery mildew is needed in high-pressure situations. However, infection potential will depend on the weather conditions in a given year.
Fungicide options with reminders:

Group 3 products Nova and Fullback are very effective. However, do not use them more than two times consecutively to avoid resistance development. They are ineffective on scab due to resistance, so use in conjunction with a fungicide that manages apple scab. Fullback and Nova are systemic and given a long drying period of 24 hrs they should be well-absorbed into the plant before a rain event.
Group 7 containing products are Luna Tranquility, Inspire Super, Sercadis, Excalia, Fontelis. For Luna Tranquility, activity for scab control is only provided at the high label rate. Fontelis contains a mineral oil in the formulation so do not use near captan or folpet products.
Aprovia Top is a combination group 3 + 7 product, therefore, be careful that you do not make more than two consecutive applications of group 3 or group 7 containing products.
Migiwa is a new chemical group 52 that may be incorporated into the program to strengthen resistance management. Migiwa also has control of apple scab and it should always be used at the high label rate.
Gatten is a new group U13. The product does not have activity on apple scab.
Property is a new group 50. The product does not have activity on apple scab.
There is industry resistance to group 11 products such as Flint so it should NOT be used for powdery mildew management.
Other products are listed in the pest management guide.

Remember to treat 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.

Fire Blight Prevention

Recommendations:

Now that the tight cluster stage is reached, ooze may be present on overwintering cankers. Pruning 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.
If interested in pinching buds on young trees the practice can begin around the bud separation stage when it's possible to avoid removing the terminal shoot. Pinching buds becomes risky as bloom begins because fire blight bacteria grow on the flower stigma and are expected to be present in high numbers in warm weather. Do not pinch flowers when tissues are wet. This practice is time-consuming and any remaining flowers are susceptible to infection.
Apogee/Kudos is first applied at 2.5-7.5 cm of shoot growth so it is still a little early. The product takes 10 days to become active so for the maximum effect on fire blight suppression it may be applied before fire blight symptoms appear. The product is not systemic so good coverage with high water volume is required.

Please note that Apogee is being discontinued by BASF next year. Kudos is the same active ingredient and will remain available. BASF will continue to support Apogee that has been sold into the channel until all inventory is exhausted.

Stone Fruit - Brown Rot

Fungicide protection from brown rot should be maintained during periods of warm and wet weather during bloom. When wet weather is expected, a fungicide applied at pink or early bloom and again during full bloom might be required. Otherwise, flower infections provide extra infection pressure for fruit infections later on.
When rain is expected, apply fungicides enough in advance to allow the spray to dry.
For plums, the use of Captan/Maestro for brown rot during the white bud stage through fruit set will also give some control of new black knot infections.
Rotating classes of brown rot fungicides is key to slow resistance development. Products are listed in the Stone Fruit Pest Management Guide.

Insects

European Red Mite

A delayed dormant oil is effective at managing European red mite if monitoring indicates a treatable overwintering egg population.

Recommendations:

Oil should NOT be applied to young trees and it is now too late to apply to trees with Delicious parentage (Ambrosia, Gala, Delicious) that risk injury.

As of today, Erika with Agricultural Pest Monitoring has not observed egg hatch. Hatch is expected to begin soon so the opportunity to apply oil for effective results will soon close.

Try to avoid applying oil before heavy rain because it is a contact product that can be washed off before it smothers the mite eggs. Even if oil is accidentally washed off by rain, never reapply oil because too much can greatly affect tree health by delaying leafing out and cropping potential.

European red mite eggs overwinter in the cracks on buds and spurs so high water volume is needed to reach all of the crevices.

Tree Borers

Grafted over trees shown in Figure 5 might be particularly attractive to borers as they are stressed when they are cut. A number of factors like the drought and tree health might increase the presence of borers.

Trees stressed by drought are at higher risk for borer infestation, and may already be showing early signs of damage. These insects are opportunistic—they target trees that are weakened and less able to defend themselves. When a tree is injured, it can release volatile chemicals that act as a signal, drawing borers in and increasing the likelihood of further decline.

A tree infested by borers often shows a telltale sign: watery sap seeping from a small hole in the bark (Figure 5). Trace the source of the sap and make a thin vertical incision through the bark to inspect the area. If borers are responsible, you will uncover a small entry hole beneath the surface. Several cases are being reported this spring.

Local studies in the 1980s evaluated insecticide treatments, following significant cold injury that increased borer activity. However, the insects’ location beneath the bark and the difficulty in accurately timing adult emergence limited the success of chemical control. Past experience suggests borer pressures subside once the initial stress event passes and weakened trees die and are removed from the orchard.

Figure 5: A grafted, top worked tree being bored into by a boring insect. When an adult borer enters a tree, a clear to brown sap can leak from the entry hole. She lays her eggs within the tree so larvae and pupae develop under the bark, forming tunnels. Photos taken May 6, 2026.

Pre-Bloom Insects

Table 2: A summary of pre-bloom insects and insecticides. Click to enlarge.

Spring Caterpillar Complex (winter moth, green pug moth, eyespotted bud moth, speckled green fruitworm, obliquebanded leafroller)

Spring caterpillars become visible on flower buds at the tight cluster stage by opening the leaves and separating buds. Caterpillars are extremely small at the tight cluster stage (~3 mm long).

Recommendations:

Choose pre-bloom insecticides according to the pest complex on your scouting report. Refer to the Table 2 summary or the full Apple Efficacy Guide for product selection. You may begin by determining the product and rate for your most difficult to control pest and then note the other pests that will be managed by your product selection and whether or not additional products are required. Take note of the higher rate required for some pests.
Treatments for spring caterpillars should not be applied too early because product must enter the developing flower clusters where the larvae like to feed to be effective. Treatments should be applied pre-bloom so target the pink stage according to heat and your monitoring reports.
If treatments for obliquebanded leafroller are required at pink, the treatments will also have some activity on winter moth and green pug moth.

European Apple Sawfly

Recommendations:

In orchards with a history of damage and high numbers of EAS catches, an application of a group 4 or group 28 product at full pink and prior to bloom is recommended to control the adults prior to egg laying.
For organic management, Surround is registered for application at first detection and throughout egg laying.

Tarnished Plant Bug

Recommendations:

If history of tarnished plant bug damage indicates that pressure is moderate to high, an application of insecticide at pink is warranted. Treatment must be applied before bloom, not after. Best effect achieved when treated as close to bloom as possible.
Pyrethroids (group 3) and Closer/Cormoran (group 4) are registered for control.
As a reminder, pyrethroids are best used at moderate temperatures (25°C or less) and are harsh on beneficial insects and predator mites. They should only be used where potential losses justify their application.

Rosy Apple Aphid

Recommendations:

One rosy apple aphid is equivalent to a colony because the first generation are all female that give birth to living young. They have a preference for flower/fruit clusters.
Monitor for rosy apple aphid populations that exceed thresholds.
Treatment pre-bloom is ideal for good coverage before aphids curl leaves. Closer works well for aphid control.

Horticulture

Sap Guttation in Topworked Grafted Trees

Sap can sometimes leak from small pores or wounds on a tree—a natural process known as guttation. This typically occurs when soil moisture is high, temperatures are cool, and a healthy root system is taking up more water than the tree can release through transpiration. The sap produced during guttation is initially watery but may dry into a sticky residue.

In Figure 6, sap was observed at the heartwood and graft unions across many grafted trees. This consistent pattern suggested that the cause was guttation rather than fire blight. These observations followed heavy rainfall in early May, combined with a rapid shift to warm, humid conditions. There is no action required because the sap will stop bleeding and trees will heal unless there is underlying damage that prevents healing.

If you are unsure whether you are seeing signs of guttation or fire blight, please don’t hesitate to reach out.

Figure 6: Sap guttation observed on grafted, top worked trees on G.890 rootstock. Photos taken on May 6, 2026.

Grafting

Check for bark slipping.
Our region benefits from leaving a nurse limb but there is no consensus on how long to leave the limb. More vigorous rootstocks likely need the nurse limb for longer.

Pollination

Consider plans to move honeybees into the orchard for pollination when king flowers open.
Remember last year when poor weather conditions restricted the opportunity for pollination to a few short days. Also, solid variety blocks rely on plenty of bee activity.

Mowing

Keeping the orchard floor cover mowed pre-bloom will minimize dandelion flowers that attract bees, which increases the safety of pre-bloom insecticide applications.

Pruning and Training

Established trees are best when pruned prior to bloom unless you wish to reduce vigour.
Ensure that deer fencing is installed as soon as possible to protect new growth on young trees.
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).
Scoring and notching above paradormant buds should be completed by bloom time.

Water Management

Mark drainage failures and repair drainage before trees are planted to prevent underlying drainage issues that would influence the planting for the rest of its life.

Weed Management

Winter annual weeds like henbit, chickweed, and shepherd's purse, and perennials like dandelions are currently in bloom. Apply post-emergent herbicides before these plants set seed to prevent the next generation of the weed population. After the winter annuals set seed the plants will die naturally and control is too late.
When burndown products are needed:

Reglone works in cool and cloudy conditions.
Ignite requires warm and sunny conditions. Also, applying Ignite when leaves are wet is ineffective.
Glyphosate and 2,4-D require daytime highs of 10°C-15°C. Activity of glyphosate is best when applied from noon to 6 PM.

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.
Trees planted this year would have received a good settling rain by now and you may consider a residual herbicide before the next rain.

Most residual herbicides need about 1/2" of rainfall within 7 to 14 days of application to deliver product to the germination zone and to activate the chemical by putting it in solution.

Note that residual herbicides can damage single tree replacements of young trees if the product is not registered for use on young trees. Keep this in mind if you are considering planting single tree replacements after the drought.
Damage may occur by planting into soil with herbicide residue or by mistakenly applying new residual herbicide.

The following residual herbicides can persist longer than usual in extreme circumstances like drought: Authority, Chateau, and Alion.

Fertilizing

Foliar nutrients to correct nutrient deficiencies:

Boron: Applied pre-pink. Do not use water soluble pesticide bags in a tank mix with boron and rinse the tank well before and after boron. Do not use boron with oil or Epsom salts.
Magnesium: Epsom salts are applied starting at pink. Do not use with oil or boron.
Nitrogen: Urea may be used from pre-pink to mid-June as a nitrogen supplement. Sprays near bloom give a boost of nitrogen when it is needed most. Urea used from tight cluster to mid-July can remedy a nitrogen shortage.
When foliar nutrients are applied in slow drying conditions, about 40% is absorbed in 6 hours. When applied in dry conditions, about 75% can be lost in 48 hours. Foliar nutrients are not well-absorbed at below 10°C.

Finish fertilizer applications soon. Bud break to bloom is the ideal time for granular fertilizer application to maximize tree growth. A new resource written by Keith Fuller is now available, "Managing Nitrogen Supply in Mature, High-Density Apple Orchards in Nova Scotia." We are pleased to introduce this resource that includes a guide for estimating nitrogen fertilizer rate using soil organic matter content and cropping potential!
Apply granular fertilizer to newly planted trees now that soil has settled from rain.

Now Available: Perennia 2025 Post-Drought Wood Analysis Investigation

The 2025 extreme drought left its mark on fruit quality, yet tree‑level effects were more difficult to detect. Growers finished the season with more questions than answers—what was happening inside the tree, what was stored for next year, and what does this mean for the 2026 crop? Through collaboration with local growers, Scotian Gold, and AAFC researcher Harrison Wright, we set out to shed light on these unknowns. This report brings together what broad research already tells us and what our local investigation revealed.

A summary of the results were presented at the NSFGA Spring Workshop on April 1. The full report is now available to share local research findings and practical lessons for apple growers.

Now Available: Year 2 Report for 2025 Thinning Trial

A summary of the results of the 2025 thinning trial were presented at the NSFGA Annual Convention this past winter on January 28. The full technical report is now available to summarize the work in more detail.

This report is a progress update that summarizes the results of the second year of a three-year project. In year one the results are preliminary and should be interpreted with caution. However, through this report we wish to share with industry our progress and early interpretations. The project is a collaboration led by Dr. John Cline, University of Guelph, with field work done in Ontario and supported by additional field work in Nova Scotia representing Eastern Canada by Michelle Cortens, Perennia. The current report summarizes only the Nova Scotia site.

This interprovincial project has several objectives, and the two objectives addressed at the Nova Scotia site are to,

Compare and validate crop load management (computer) models to predict and improve thinning outcomes using chemical thinners, and
Determine the effect of chemical thinning products, different timings, and concentrations on fruit thinning efficacy of apple.

You can access the report to download and print from the Perennia website.

Events and Notices

Atlantic Agronomy & Extension Conference

Join Perennia and our partners, the Prince Edward Island Federation of Agriculture (PEIFA), New Brunswick Soil and Crop Improvement Association (NBSCIA) and the Newfoundland Federation of Agriculture (NLFA) in the beautiful Annapolis Valley for the On-Farm Climate Action Fund (OFCAF) Atlantic Agronomy and Extension Conference—moving beyond the “what” of BMPs and focusing on the “how” of extension.

This engaging two-day event is designed to spark ideas and drive impact. We’re bringing together leading voices from across Canada, the United States and the United Kingdom to showcase practical, real-world approaches to communicating, teaching and accelerating the adoption of OFCAF-supported beneficial management practices (BMPs). Whether you are a student, agronomist, agrologist, extension specialist or technical advisor, this conference is for you.

Connect with peers, gain fresh insights and leave inspired with extension tools you can put into action right away. Register Today!

Perennia Now Offering Analytical Testing

Effective May 1, 2026, Perennia is fully operating the former Nova Scotia Department of Agriculture (NSDA) Analytical Lab at the Harlow Institute Building, 176 College Road in Truro.

In addition to mineral and bacteria water testing, we are conducting the same tests as previously offered:

Soil analysis for lawn, garden and field samples
Soil amendment analysis
Greenhouse soil, nutrients and water + field, milk house water, etc.
Feed analysis
Digest samples
Plant tissue analysis

We are also continuing to offer the 50 per cent discount on the same tests as when the lab was operated by NSDA for farmers with a current farm registration number. Our service fees also haven’t been changed and the overview PDF is available at https://www.perennia.ca/analytical-lab

For drinking water samples, Perennia is referring and transporting these daily Monday to Thursday to an accredited lab in the HRM. NSDA’s ISO accreditation for this testing was not transferrable to Perennia. Thus, we are doing all the extensive paperwork required for a new ISO accreditation for Perennia and anticipate taking drinking water samples after a successful audit this summer. We will keep everyone updated. For now, water samples for these tests can only be accepted at the Harlow Building in Truro.

All other samples can continue to be dropped off at:

NSDA Digby, Antigonish and Kentville offices (Kentville will be phased out as a drop off location in the coming weeks)
Nova Scotia Department for Natural Resources and Renewables Strathlorne Nursery in Inverness
Harlow Building in Truro
Perennia office in Kentville (28 Aberdeen Street – drop off will be at the entrance at the back of the building facing the side of the Independent grocery store. Parking is available – feel free to park in the space directly in front of the door for quick drop off.)

Soil collection supplies can also be obtained at these locations along with submission forms and resources.

All drop-off dates and times, locations, submission forms, how-to resource forms and interpretation guides, payment methods and fee listing are all available at www.perennia.ca/labservices where you can also order tests from our Plant Health Lab.

For more information or questions please contact labs@perennia.ca

Local Supplier Food Safety Support Pilot Program

The Province is investing in a new Local Supplier Food Safety Support Pilot Program to help food producers meet food safety requirements they need to get more of their products to local and global markets.

The departments of Growth and Development and Agriculture have partnered with Perennia Food and Agriculture Corp. on the two-year pilot program for Nova Scotia food and beverage producers. The program will help with costs related to food safety standards such as training, assessment, program development, audit fees and facility upgrades.

The support will help more local producers meet provincial and federal food safety standards that can be a barrier to growing their business.

Deadline to apply is July 15, 2026. For program guidelines and application, visit our website.

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: Larry Lutz, Harrison Wright, Joan Hebb, Danny Davison, Ian Willick, Colin Hirtle, Mathew Vankoughnett, Shawkat Ali, Dustin MacLean, and Heather Rand.

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

Pages

Orchard Outlook Newsletter Vol. 26, No 5

Tuesday, May 12, 2026

Table of Contents:

Weather

2026 Degree Day Accumulations

Precipitation

Bud Development

Apple Buds

Pear and Stone Fruit Buds

Hazelnut Buds

Diseases

Apple – Scab

Recommendations:

Apple – Powdery Mildew

Recommendations:

Fire Blight Prevention

Recommendations:

Stone Fruit - Brown Rot

Insects

European Red Mite

Recommendations:

Tree Borers

Pre-Bloom Insects

Recommendations:

European Apple Sawfly

Recommendations:

Tarnished Plant Bug

Recommendations:

Rosy Apple Aphid

Recommendations:

Horticulture

Sap Guttation in Topworked Grafted Trees

Grafting

Pollination

Mowing

Pruning and Training

Water Management

Weed Management

Fertilizing

Now Available: Perennia 2025 Post-Drought Wood Analysis Investigation

Now Available: Year 2 Report for 2025 Thinning Trial

Events and Notices

Atlantic Agronomy & Extension Conference

Perennia Now Offering Analytical Testing

Local Supplier Food Safety Support Pilot Program

Pest Management Guide

Blog Archive