The newsletter reflects the limited bud growth that occurred over the last week, but notes more widespread green tissue. The weather forecast predicts rain showers that will bring needed moisture and also signals the risk of the first apple scab infection event. While you're pruning, remove dead wood like the black rot cankers shown in our example. Given the upcoming prediction of rain, it is highly encouraged that you apply granular nitrogen to make it available for new root growth. For guidance on nitrogen management, we introduce a new factsheet written by Keith Fuller. This week may also be a good opportunity for application of residual herbicides that need rain for activation. The use of mulch to prolong moisture retention is discussed. Many thanks for the ongoing commitment of the Orchard Outlook Committee members.
Table of Contents:
- 2026 Degree Day Accumulations
- Soil Temperatures
- Apple Buds
- Pear and Stone Fruit Buds
- Hazelnut Buds (NEW!)
- Follow Up on Critical Spring Temperatures
- Apple - Scab
- Fire Blight Sanitation
- Black Rot Cankers
- Stone Fruit - Black Knot
- Delayed Dormant Oil - Cautions and Considerations
- Scale Insects
- Efficacy of Herbicides
- Crop Safety of Common Herbicides
- Moisture Retention
- Fertilizing
- Planting Trees
- Pruning
- Blind Wood
- Liming
- On-Farm Nursery
- Nutrient Management Planning Web Series
Weather
2026 Degree Day Accumulations
Over the last week the degree day accumulation was slowed by cool temperatures. The cumulative degree days are now behind the 5- and 10-year averages (Figure 1). The heat accumulation and development stages are relatively similar to this same time in the year 2017 and 2023.
Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to April 27 for the past 17 seasons. Provided by Harrison Wright (AAFC Plant Physiology).
- Approximately 17% less plant development heat units compared to the 5-year average, and 5% less compared to the 10-year average.
- Approximately 20% less plant development heat units compared to 2025, and 10% less compared with 2024.
- Approximately 22% less insect development heat units compared to the 5-year average, and 14% less compared to the 10-year average.
Soil Temperatures
Currently, the soil temperature at 35 cm deep is near average at around 8°C (Figure 2, red line). Measurements by AAFC at 15 cm depth are anywhere from 8-16°C and such temperatures are conducive to growth of new feeder roots. Root growth usually begins where soil temperatures reach around 9 to 10°C. New root growth is white or tan coloured and succulent.- Ideally, with the new root growth expected to occur, target granular nitrogen fertilizer before the upcoming rain.
- Early tree planting allows new trees to grow new roots early in the season before the heat of summer discourages further root growth.
- Samples of root lesion nematodes may be taken in the spring when soil temperatures are consistently 10°C and moist. However, based on local research we determined that spring samples will suggest only if root lesion nematodes are present. Spring samples are misrepresentative of the actual carrying capacity or pressure from root lesion nematodes in orchards, and for this reason fall samples are preferred for pre-plant planning.
Figure 2: Soil temperatures at 35 cm depth at the Kentville Research Station from 2021 to 2026. Provided by Harrison Wright (AAFC). Each year is represented by a colour and the 10-year average is the black dotted line.
Bud Development
Apple Buds
An early region on Middle Dyke Road in the Kentville area is monitored to guide this newsletter. Yesterday on April 27, the Idared buds were at 1/4 inch green, Honeycrisp was at green tip and Ambrosia was at green tip (Figure 3). Very little growth has occurred over the past week but green tissue has now been exposed from scales on varieties like Honeycrisp and Ambrosia.
Figure 3: Bud development in an early region on Middle Dyke Road in Kentville on April 27. Shown from left to right: Idared, Honeycrisp, Ambrosia.
Pear and Stone Fruit Buds
Figure 4: Bud development on April 27. 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 (NEW!)
Yes, you read that right... hazelnuts! 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.
Ian shares that the hazelnuts are now flowering (Figure 5, left). He describes that red stigmatic styles on female buds are visible, pronounced, and receptive. Some male catkins are visible (image not shown) but limited due to the age of the orchard (planted in late spring 2025). Swollen vegetative buds are seen together with open buds with folded leaflets (Figure 5, right).
Figure 5: Hazelnut bud development on April 27. The buds were in full bloom (left). The vegetative buds were at swollen to early bud break (right). Photos from April 27th 2026 courtesy of Emma Adams and Ian Willick.
New vegetative growth is susceptible to eastern filbert blight infection. Time to start thinking about preventative sprays! For Eastern Filbert Blight (EFB) management:
- Wood with cankers should be removed prior to bud break. Destroy pruned wood (burn or chip).
- Emerging green and reproductive tissues are susceptible to infection via Anisogramma anomala spores. Therefore now is the time to start applying protective fungicides. Applications should start when ~ 50% of buds show leaf tissue.
- Some good news - we have not observed any presence of EFB in the Kentville AAFC test orchard (all hybrids). Hazelnuts of pure European heritage are more susceptible than hybrid crosses containing Asian parentage.
- Sprays: Flint or Flint Extra; Miravis Duo; Quadris flowable, Bravo ZN/ZNC; copper-based sprays; Quash/Quash Duo (Quash products may require more information).
Follow Up on Critical Spring Temperatures
Last week on the morning of Wednesday, April 22 cold temperatures were recorded in tree fruit growing regions. Luckily, apples were at an early growth stage of silver tip to green tip and only temperatures below -7.8°C are expected to cause apples, and the critical temperature was not exceeded. Damage is not expected, however, I have not yet checked for signs of injury.
Injury to 10% of peach buds can occur at temperatures below -6.1°C. From the network of ten NSFGA Davis weather stations, the coldest temperatures were recorded at Aylesford -6.8°C, Windsor -6.6°C, North Medford -6.3°C, and Melvern Square -6.1°C. Peach injury is possible at or near these locations.
The cold temperatures swept across the US and I'm hearing reports of damage to fruit buds in the US. Their buds were move advanced than ours and in some cases ahead of schedule.
Diseases
Apple – Scab
For industry monitoring purposes, a green tip date of April 19 will be used for predictions of ascospore maturity this year. An apple scab infection event has not yet been recorded. The environmental conditions for an infection are listed in the Modified Mills Table.Recommendations:
- Green tissue should be protected with fungicide prior to the first predicted infection event.
- Rain showers are now in the forecast. According to the current forecast, an infection could occur on Friday at which point 6.0% of ascospores are forecast to be mature (4.4% since last rain).
- At an average forecast temperature of 10°C, a leaf wetness lasting 14 hours is enough to trigger an infection.
- According to the forecast, ascospores are maturing at a rate of 0.7-1.2% per day.
- Reapply protection on a 7-day interval, with a shorter interval after wet weather (cumulative 1-2” rain) or rapid tissue growth.
- Good early-season fungicide options:
- Copper spray + half rate mancozeb: With no frost in the current forecast this is a good option. Copper spray alone would be risky given 4.4% of ascospores and the risk of multiple rain showers. Mancozeb would redistribute and improve protection. Only consider copper on varieties with less than 1/4 inch green tissue.
- Mancozeb products (manzate, penncozeb, dithane) are compatible with oil. They may be applied at up to 24 kg/ha/year whether that is up to 4 full-rate applications or up to 8 half-rate applications. The re-treatment interval is 7 days and the re-entry for pruning is 12 hours.
- Scala + half rate group M performs well in cool weather but needs tissue for uptake so likely best used as a second spray. Use before powdery mildew risk period because it has activity on scab only. The re-entry for pruning is 12 hours.
- Captan/Maestro and Folpan/Follow should be avoided within 7-14 days of an oil application. If you are not applying oil for European red mite, then these products can be used for early black rot management in high pressure situations. The re-entry for pruning after Folpan/Follow is 12 hours, and for Captan/Maestro is 4 days for low density and 6 days for high density.
- Allegro/Vantana/Downforce can be used within 1-3 days of oil. The re-entry for pruning is 24 hours.
- Buran is used post-infection only.
- Early in the season, there is no need to control powdery mildew so products with activity on powdery mildew can be saved for application at half inch green.
Fire Blight Sanitation
The goal of copper application is to cover the bark with copper to reduce the population of bacteria on plant surfaces that arise from bacterial ooze around the pink stage. The copper treatment will reduce the initial inoculum and limit the spread of fire blight bacteria to blossoms or wounded tissue on the tree but does not replace the need for blossom blight management. The copper sanitation strategy is most effective in blocks that had fire blight cankers in the previous two seasons.
Recommendations:
- A copper application is recommended when buds are at the green tip stage and no later than 1/4 inch green for fresh market varieties, after which phytotoxicity becomes a problem. Processing varieties where russet is tolerable can be treated later as well as nonbearing trees.
- Copper will provide some fungicidal activity on apple scab but does not redistribute in rain so use a mancozeb fungicide as well if possible.
- A fixed copper product such as Copper Spray Fungicide (50% copper oxychloride) is recommended because it is resistant to being washed off bark surfaces by rain.
- Copper can be applied as a tank mix with 0.5% by volume (5 L in 1000 L) dormant oil to increase adherence. Apply for good coverage of plant surfaces. In other words, a concentrate volume applied to every other tree row would not provide enough coverage. Given time constraints, prioritize blocks with a history of fire blight.
- Cankers are visible now before they become hidden by this year's foliage. Scout for cankers now.
- If in doubt, take it out! No cankers are helpful and they harbour diseases. If you need a second opinion, I can take a look. Cankers are especially risky in young orchards because they harbour the bacteria for new blossom infections that give bacteria rapid access to the leader of the tree. Consider completely removing young trees that have cankers.
Black Rot Cankers
Black rot of apple is an increasingly important fungal disease in Nova Scotia orchards. It is caused by the fungus Diplodia seriata (syn. Botryosphaeria obtusa), which can infect fruit, leaves, shoots, branches, and trunks. Most importantly black rot can asymptomatically infect fruit in the field, causing fruit rot in storage. Currently most preferred commercial varieties are susceptible to black rot, making proper management of the disease critical.
One of the best methods of controlling the disease is removing inoculum. The disease overwinters in mummified fruit (the previous year’s infected fruitlets) and in dead or diseased wood where it forms cankers. Black rot cankers symptoms start as sunken, reddish-brown lesions on limbs or trunks. Then the bark becomes rough, cracked, and flaky and may contain black pycnidia (spore structures)(Figure 6).
Earlier this spring Michelle, Dustin (Plant Pathologist, Perennia) and I inspected a small number of apple blocks with known canker issues. A high incidence of black rot was found, especially on weakened trees or dead wood. When pruning in spring after active growth has commenced, remove symptomatic limbs at least 15–20 cm below visible symptoms, and if possible prune blocks during dry weather especially if they have symptoms of cankers.
One of the best methods of controlling the disease is removing inoculum. The disease overwinters in mummified fruit (the previous year’s infected fruitlets) and in dead or diseased wood where it forms cankers. Black rot cankers symptoms start as sunken, reddish-brown lesions on limbs or trunks. Then the bark becomes rough, cracked, and flaky and may contain black pycnidia (spore structures)(Figure 6).
Earlier this spring Michelle, Dustin (Plant Pathologist, Perennia) and I inspected a small number of apple blocks with known canker issues. A high incidence of black rot was found, especially on weakened trees or dead wood. When pruning in spring after active growth has commenced, remove symptomatic limbs at least 15–20 cm below visible symptoms, and if possible prune blocks during dry weather especially if they have symptoms of cankers.
Figure 6: Examples of black rot cankers in mature orchard. The fungus lives in dead wood (left). Established cankers become rough and cracked (centre). A close up reveals black pycnidia spore structures (right). Photos taken by Matt Peill, April 9, 2026 and symptoms confirmed by lab analysis by Dustin MacLean.
Stone Fruit – Black Knot
Recommendations:
- Prune limbs 15 cm beyond the knot and destroy knots (burn or flail mow).
- Remove knots before bloom. New shoots are susceptible to infection risk during active shoot elongation. Most infections are believed to occur just before or during bloom, or after petal fall.
- Removing the fruiting bodies will not eradicate the fungus in the orchard but it will help keep the pressure down.
- Flag wild trees surrounding the orchard that might also carry knots and remove them when time allows.
Insects
Delayed Dormant Oil - Cautions and Considerations
- When green tissue is present, do not use dormant oil 48 hours before or after freezing temperature.
- For varieties with Delicious parentage (Ambrosia, Gala, Delicious), early applications of oil prior to tight cluster are less likely to result in bark blistering.
- Oil should NOT be applied to young trees.
- Consider the greater water volumes needed for large canopy trees that have not been pruned yet versus trees that have been pruned. Apply thorough coverage of the bark that is appropriate to the orchard situation.
Scale Insects
The best time to target scale is ideally just before the tree breaks dormancy or with a delayed dormant spray of oil by green tip. The treatment opportunity has lasted up until now and will soon come to a close.
The timing for targeting scale is not similarly effective for mites. The timing for mites is geared toward egg hatch, which is after bud break and closer to tight cluster. Target your oil application for the more important pest issue.
Weed Management
Efficacy of Herbicides:
- 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. If the forecast holds true, this week is a good opportunity to apply residual herbicides before the upcoming rain.
- Glyphosate and 2,4-D require daytime highs of 10°C-15°C after a night above 3°C to have good activity and weeds must be actively growing. Activity is best when applied from noon to 6 PM. This week the weather is conducive to good efficacy.
- Perennial weeds may be targeted in spring when new perennial plants are at the seedling stage. Other timings are spot sprays at the early flowering stage or during fall re-growth after a minor frost. Glyphosate and group 4 products are systemic and work on some perennial plants.
- If weeds are already present, add a post-emerge to a residual herbicide to achieve control.
- Treat grasses early in their growth stage for best control.
Crop Safety of Common Herbicides:
- Wait for a settling rain before applying residual herbicides to new plantings.
- 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.
- Speaking of the drought, the following residual herbicides can persist longer than usual in extreme circumstances like drought:
- For Authority, instead of waiting the usual 2 years for reapplication, you should wait 3 years since your previous application. The label advises a 3-year replant interval under normal circumstances and extended an additional year to a 4-year replant interval after drought.
- For Chateau, the rotational interval is 1 year. However, the label also says, “After periods of extended drought longer rotational intervals may be needed.”
- For Alion, there is no specific mention of drought in terms of replanting, but waiting longer than 12 months might be advised.
- In the USA, there are concerns about Ignite causing bark cracking. The specific risks are yet to be defined but just be cautious that Ignite is not sprayed onto or drifts onto young tree bark.
- Chateau should not be applied after budbreak unless application equipment is shielded to prevent crop injury.
- If you are taking out orchard within the next 2-3 years for replanting, avoid applying residual herbicides. The Alion label says to allow at least 12 months from last application to replanting an orchard.
- When mixing residual herbicides, agitation is important to keep the product in solution. If the herbicide settles in the tank then it can be delivered in a high concentration and possibly result in crop injury.
Horticulture
Moisture Retention
Soils appear to have less moisture than usual at this time of year because of the 2025 drought and the month of April is running 30 mm behind average precipitation. The forecast has also shown a pattern of scaling back precipitation.
- Applying mulch early in the season while the soil has moisture is more effective at retaining moisture than waiting until midsummer. Apply a herbicide first.
- The historical recommendation for the tree row has been to apply sparse hay mulch at 0.5-1 kg/m2. Hay may be difficult to source after the drought and also presents a risk of introducing new weed seeds.
- Explore using straw mulch, in particular in areas of sandy knolls or on lighter soils where trees struggled last year. Apply to a depth of only a few centimetres to simply provide a physical barrier that reduces evaporation from the soil surface. It also shields the soil from sun to lower the temperature and slows the impact from rain droplets to improve infiltration.
- Alternatively, practice season-long mow-and-blow to move the laneway grass clippings into the tree row. Creating a few centimetres of grass clippings has a big benefit.
- Ultimately, mulch can improve organic matter and long-term moisture retention.
- As an additional benefit, mulch reduces migration of two-spotted spider mite from weedy hosts.
Fertilizing
- Bud break to bloom is the ideal time for granular fertilizer application to maximize tree growth.
- Spread granular fertilizer before the upcoming rain for the greatest benefit.
- 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!
Planting Trees
- Planting conditions are generally good now with temperatures conducive to root growth and workable soil. Take advantage of existing moisture.
- Remove old roots and work to get a good soil tilth without sods and clods especially in the top 15 cm of soil.
- The length of the rootstock that is above ground level will influence tree growth. Tree size diminishes as the rootstock portion above ground increases. Trees should be planted so that the graft unions are at a uniform height of 8 to 10 cm above the soil line after stomping into the ground.
- Avoid letting trees dry out. About 40% of trees can die from drying out, and surviving trees grow slowly. Survivors of 15-minute dry winds recover by year 3. Survivors of 45-minute drying winds still don't grow well by year 3.
- Bundles of trees sitting in water awaiting planting can asphyxiate, especially in stagnant water and/or warmish water.
Pruning
- Plan ahead and watch re-entry intervals for pruning activities when fungicide programs begin.
- Ensure that youngest blocks are pruned first so growth is directed into desirable leader and terminal extension. Prioritize high value trees and then return to low value areas.
- Consider prioritizing pruning in fire blight blocks to finish prior to tight cluster when cankers begin oozing. Cut out cankers, whether fire blight or other diseases.
- Pruning may be delayed closer to bloom for vigorous Ambrosia to reduce its vigour.
- Mature blocks can be pruned later and are best when pruned prior to bloom.
- A handout for farm workers 'The Fundamentals of Pruning' is available in English and Spanish.
Blind Wood
- In general, scoring and notching is best done from green tip and up until bloom time. The ideal time is at the stage of half-inch green.
- An excellent local on-farm trial done by Walsh Farms was shared during a previous Growing Good Growers tailgate meeting. They tried different treatments of notching, scoring, and growth regulators around May 5, 2024 on young Ambrosia trees. Their results and some of the discussion is referenced here:
- Success ranged from 7% to 25% branch induction.
- In this situation, scoring worked better than notching. Scoring resulted in more branch elongation. The growth regulators did not improve success. Growth regulators can be affected by the weather at application so results might depend on the conditions in any given year. Growth regulators are discussed in this article.
- Most people concluded that the practice of notching and scoring was time consuming, especially during the narrow opportunity in spring.
- Treating blind wood is likely only worthwhile if the success rate is 20% or higher.
Liming
- Lime soils prior to planting an orchard with rates according to your soil report. Early spring is an option but fall can be a more practical time to apply lime to a new site and lengthen the time for acidity to become neutralized.
- Orchard maintenance with surface applied lime twill take a number of years to adjust pH of the soil profile so it is best to apply annually or biannually where needed. If soil testing for pH, measure during the same time each year (August) as pH can change over the growing season.
- The provincial limestone trucking assistance program is open.
On-Farm Nursery
- If planting bench grafts, it is best to wait for the soil temperature to be warm enough for bench grafts to grow. It is better to wait for warm soil than to let the grafts sit. Also, keep in mind that the new callus is susceptible to damage from freezing temperatures.
- Early application of granular fertilizer can minimize the risk of leaf burn. Otherwise, granules can get trapped and sit in new leaf tissue that is close to ground level.
Events and Notices
Nutrient Management Planning Web Series
Whether you're an agronomist, extension or industry professional, or interested in sustainable soil management, this series will give you valuable, actionable insights you can apply right away.
May 4 - Phosphorus management
May 11 - Base cations
May 19 (Tues) - Manure and organic amendment management
Register online here to join!
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: Jeff Franklin, Larry Lutz, Harrison Wright, Danny Davison, Joan Hebb, Ian Willick, Suzanne Blatt, Keith Fuller, Bob Prange, Jill MacDonald, Heather Rand and Colin Hirtle.
Edited by Michelle Cortens, Tree Fruit Specialist
Perennia Food and Agriculture Corp.
Perennia Food and Agriculture Corp.
