This week’s Orchard Outlook shows symptoms of this year's scab and powdery mildew pressure, while also turning attention to summer diseases as you consider extending fungicide spray intervals. Caution is warranted because fungicide residues can be significantly reduced after 50–60 mm of rainfall, and stretching spray programs too far may create opportunities for summer diseases such as flyspeck to establish. With heightened vigilance around the appearance of fire blight blossom blight symptoms, we are also seeing similar-looking issues, including Pseudomonas blossom blast. In addition, reports of tree decline in the field are discussed, along with our current thoughts on possible causes. On a positive note, last year’s newly planted trees are showing exceptional growth - a welcome highlight this season! As always, thank you to the Orchard Outlook Committee for their continued dedication and contributions.
Table of Contents:
- 2026 Degree Day Accumulations
- Apple Buds
- Frost Symptoms
- Apple - Scab
- Apple - Powdery Mildew
- Fire Blight Infection Management
- Apple and Pear - Pseudomonas Blossom Blast
- Apple - Fire Blight Blossom Blight
- Apple - Black Rot
- Apple - Brooks Spot
- Apple - Flyspeck and Sooty Blotch
- Tree Decline
- Solstice Reminders
- Nutrition
- Suckers
- Mowing
- Pruning and Training
- Weed Management
- Nursery Trees
- Cover Crops
- Summer Hedging
Weather
2026 Degree Day Accumulations
- Approximately 1% less plant development heat units compared to the 5-year average, and 6% more compared to the 10-year average.
- Approximately 5% less plant development heat units compared to 2025, and 6% less compared with 2024.
- Approximately 2% less insect development heat units compared to the 5-year average, and 7% more compared to the 10-year average.
Bud Development
Apple Buds
An early region on Middle Dyke Road in the Kentville area is monitored to guide this newsletter. Yesterday on Monday the average diameter of ten king fruitlets on Idared was 25 mm and Honeycrisp was 24 mm. The chemical thinning window has closed. Idared now has 11-12 fully expanded leaves (+2 leaves), Honeycrisp 9-10 fully expanded leaves (+2 leaves), and Ambrosia 8-9 fully expanded leaves (+ 2 leaves).Frost Symptoms
Diseases
Apple – Scab
Where primary lesions are present, secondary infections have been occurring and will continue during wetting events of sufficient duration. The minimum wetting required for secondary infections is 3 hours less than the wetting required for primary infections.
Recommendations:
- As of June 27 it will have been 2 weeks since the ascospores were depleted, according to model predictions. Before you consider lengthening spray intervals, take a close look at the leaf canopy in the orchard to determine your risk of secondary infections. Lesions develop on the surface of a leaf and they are velvety brown in appearance. Check cluster leaves for early infections and the mature leaves on terminal shoot growth for mid season infections.
- Monitor for extended or heavy periods of rainfall because most fungicide residues are washed off by a cumulative total of 50 to 60 mm of rain (2 to 2.5 inches). Summer diseases are a risk if spray programs are stretched to this limit.
- Folpan/Follow should NOT be applied between tight cluster and 30 days after petal fall to avoid fruit russeting. If petal fall was on the first week of June, then you may consider using Folpan/Follow in the first week of July for this timeline to be satisfied.
Apple – Powdery Mildew
Powdery mildew infections can be expected when conditions are warm (10-25°C), humid and dry.
Recommendations:
- New powdery mildew infections have been extensive this year (Figure 4). Conditions were conducive to infection throughout June on new tissue growth. Trees are susceptible to powdery mildew infections for as long as new leaves are forming on growing shoots (until terminal bud set).
- On large and mature bearing apple trees, the main economical concern is in protecting fruit against infection. Fruit infection causes stunting and russeting. However, fruit are only susceptible to infection during and shortly after bloom. The russet stretches as the fruit expands. In early June there were possible infection periods when fruit might have been susceptible. Fruit are no longer at risk of infection.
- Protection may continue on young plantings because severe infections can reduce shoot growth, which is most concerning for young, non-bearing orchards. Continuing protection this season will prevent infection of next year's buds (to protect next year's growth), and result in less carryover of inoculum to next year. Pay particular attention to susceptible and high-value varieties such as Honeycrisp and Gala. Product reapplication intervals can vary from 7-14 days.
- There is industry resistance to group 11 products such as Flint so it should not be used for powdery mildew management.
- Do not use any products with powdery mildew activity more than two times consecutively to avoid resistance development.
Fire Blight Infection Management
Recommendations:
- Cut out infections when a period of 2 dry days are in the forecast. Leave prunings in orchard laneways to let dry thoroughly for several weeks. If cutting a whole tree consider letting it dry while attached to the trellis. Don’t make piles that will prevent the wood from drying. Do not work in trees when they are wet from dew.
- As soon as you find fire blight infections, use an application of Apogee/Kudos (prohexadione calcium). Use a lower rate if trees have not filled their space or the full rate if tree growth is not an issue. The benefits of Apogee/Kudos:
- Helps suppress the progression of infection to buy you time for cutting it out.
- Builds protection in nearby trees that may not yet be infected so that if infection were to occur, the spread would be already slowed. Where infections are numerous, apply prohexadione calcium to the entire block considering that ooze can infect at a distance of at least 0.8 km away.
- Reportedly has the potential to reduce or prevent canker incidence on perennial wood.
- To save time, it is not necessary to sterilize the tools often as long as all of your cuts are in fire blight areas and during dry weather. Several research studies have concluded a lack of benefit from sanitizing tools. Where there is a tradeoff because of limited labour, it is best to work quickly rather than to sanitize tools.
- 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 and Pear – Pseudomonas Blossom Blast
Apple – Fire Blight Blossom Blight
- Bacterial growth has been gradual under moderate temperatures. Periodic protection has been advised on newly planted trees in bloom through the blossom blight alert emails - when EIP values exceed the threshold.
- EIP levels are low for the next few days and may approach the threshold again on Thursday, June 25 or Friday, June 26.
- By the end of this week I will likely conclude industry-wide blossom blight alerts.
- Contact me if you have questions about specific situations. As usual, this time of year becomes more difficult to generalize recommendations.
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. Be cautious with spray mixtures (calcium, foliar nutrients) that could create an entry point for the pathogen.
Apple - Brooks Spot
Apple - Flyspeck and Sooty Blotch
Insects
Apple and Pear: Codling Moth
Timing: The treatment timing for Rimon is 80 degree days Celsius from biofix to target eggs before they hatch.
Products: Assail, Delegate, Intrepid, Altacor, and Exirel
Timing: The treatment timing for egg hatch products is 100 degree days Celsius from biofix.
Product: Imidan
Timing: Control of codling moth with Imidan is typically slightly later at 140 degree days after biofix.
Recommendations:
- Monitor the forecast for rain and do not apply treatment before heavy rain. Codling moth lay eggs that hatch over a period of time. Late application may miss the first egg hatch and could result in a few codling moth entries but will still provide residual activity for future egg hatches.
- If trap captures are below the treatment threshold but continue to build over time then treatment should be applied once a threshold is reached. When the time for apple maggot treatments arrives, the chemistries will also treat late codling moth.
- The neonicotinoid insecticides (group 4 products) move into plant tissues over a period of about 24 hours. If it rains before the product is absorbed, the product on the surface is susceptible to wash off.
- Imidan does not penetrate leaf tissue so it is a surface material that is susceptible to wash off under rainy conditions.
Apple - Sucking Insects
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.
- Scout your orchards or check your scouting reports to see if there is a treatable population. Those growers with a consultant will receive the most accurate information because mite counts are done using a specialized machine for brushing and beneficial predators are noted as well.
- 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:
- 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.
Scale Crawlers
- If you had scale last year at the packout then they should still be monitored even if an oil application was used in spring.
- The scale that are under a waxy coating at this time of year are the adults that are about to give birth to live young. Those live young are the crawlers that leave the waxy coating and become susceptible to insecticides. Typically the crawlers are active in July at about 4-6 weeks post-bloom and with the heat this year they could be on the move early.
- Monitor for activity by using traps that are made by using black electrical tape (with adhesive side out) around the scaffold limbs of trees, in areas with known infestations. Crawlers yellow bodies will be caught on the tape when they become active.
- When the crawlers are active, Movento with a surfactant is one of the most effective products. The neonicotinoid products Assail/Aceta and Closer may also affect crawlers.
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.
- Codling moth: Refer to the above information for apples.
Crop Load
Apple Crop Load
- I haven't reviewed many sites yet, so I don't want to share detailed observations too soon.
- The majority of fruit drop has not occurred yet but the dying fruitlets within clusters are becoming more clear due to size differentiation and yellow stems. Dying fruitlets can be easily dislodged.
- What I have seen so far suggests a response to thinners and a good potential crop. The response is variable based on variety and if bloom coincided with good pollination conditions. As you assess, turn your attention away from fruit on the ground and instead look at the fruit on the tree and imagine what the crop will look like when the fruit enlarge and fill their space.
- Remember that individual Honeycrisp trees in their 'off' year might have low fruit, which is not a consequence of the chemical thinners.
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
Tree Decline
- Decline has been observed so far in Gravenstein (G.41, B.9, M.9), Ambrosia (M.9, G.41), Honeycrisp (G.41, G.11), and Minneiska (M.26). It is primarily affecting young, bearing trees on dwarf and semi-dwarf rootstocks. These trees were exposed to the cold winter temperatures from the polar vortex in 2023.
- Internal browning (internal necrosis) has been found above, within, and below the graft union (Figure 6). This browning may indicate infection by wood decay fungi that colonized the tree following earlier injury, such as winter damage. The location of the browning around the graft union suggests that this area (often the most vulnerable part of the tree) may have been injured by cold temperatures. Symptoms of winter injury can vary considerably within a single block.
- The causes of decline are still being investigated, but our theory is they are likely linked to recent extreme environmental conditions. Repeated stress events can weaken trees and allow wood decay fungi to overcome the tree's natural defences. Drought stress may have further limited the trees’ ability to heal.
- Borer insects are attracted to these weakened trees and may also limit healing. Tree decline and borers were observed locally after the cold winter temperatures in the late 1990s.
- Trees with previously weakened root systems or graft unions appear to be most susceptible. Decline is most commonly observed in areas with consistently wet soil conditions, which may have restricted the development of healthy roots.
- Please report to Michelle if you have tree collapse to help us discern patterns and develop best practices for our local region.
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.
Nutrition
- The goal of foliar Ca sprays is to increase the concentration of Ca in the fruit and reduce the incidence of bitter bit. Begin calcium applications at 4 to 6 weeks after petal fall when fruit have reached the golfball stage at around 35 mm. Calcium applied at two-week intervals is better than occasional, high-rate applications.
- Ca has very low movement within the tree and needs to be applied directly to the fruit surface to be absorbed. Therefore, thorough coverage is important to cover developing fruit.
- The recommended rate is 4.5 to 15.5 kg elemental calcium per ha (4 to 14 lbs of elemental calcium per acre) over an entire season spread over six to eight cover sprays.
- Low rates will not cause leaf burn but will likely lead to only minor control of bitter pit and likely will not enhance storage life of the fruit.
- High rates may lead to some leaf burn, give good control of bitter pit, and may also enhance storage life of the fruit.
- Determine how much elemental calcium you would like to apply over a season and then work backwards to determine the required number of sprays.
- Calcium chloride flake (77% CaCl2) is the most economical Ca material to use but also the highest risk for foliar burn. Calcium chloride flake has a low risk of leaf burn when applied at the standard rate of 4.5 kg per 1000 L of water/ha (4 lbs/100 gal/ac).
- Calcium chloride flake is 77% calcium chloride which is composed of one calcium and two chloride molecules. According to the weight of the molecules the calcium portion represents about 28% of the total weight. Therefore, our calcium chloride flake contains 28% elemental calcium.
- For each spray at the standard rate of 4.5 kg per 1000 L/ha, the 28% portion that is elemental calcium is 1.3 kg/ha (1.1 lbs elemental calcium per acre).
- The risk of leaf or fruit damage from calcium is highest in hot weather. Susceptible varieties can develop lenticel spotting if damaged. Target fast drying conditions for applications.
- Risk of leaf injury may be enhanced by Captan. Incompatibility has been observed with Epsom salts, and liquid or emulsifiable pesticide formulations in some cases. Do not apply calcium with Apogee/Kudos. Note that nutrient product formulations with calcium may contain boron that would interact poorly with water soluble packaging.
Suckers
- 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 post-bloom insecticide applications.
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 and before the shoots get woody.
- 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).
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.
- Lontrel is a great post-emergent for vetch, clovers, and sheep sorrel. Vetch is currently in bloom which is a key treatment period. Vetch is likely wrapped around tree trunks so first pull the vines from the trunk before treatment.
- 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.
- The following residual herbicides can persist longer than usual in extreme circumstances like drought: Authority, Chateau, and Alion.
Nursery Trees
- New trees have limited root systems and are likely to benefit from irrigation early during establishment.
- Treat for tarnished plant bug and green aphids.
- 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 that can be accessed from our website.
- Summer grasses such as pearl millet and sorghum-sudangrass that have been a popular choice can be planted from mid-June until early August.
Summer Hedging
- A local study by Perennia in 2013 evaluated the regrowth on summer hedging using Ambrosia on M.9 and Gala. Results indicate that the last week of June = 6 to 21 cm of regrowth, first week of July = 4 to 12 cm of regrowth, and second week of July = 2 to 3 cm of regrowth. No regrowth is expected after terminal bud set around the first week of August although it was not included in the trial.
Pest Management Guide
Perennia Food and Agriculture Corp.





