Orchard Outlook Newsletter Vol. 26, No 7

Tuesday, May 26, 2026

This week’s Orchard Outlook reflects contrasting weather that has both sped up and slowed bloom progression, along with an update on recent frost events where damage remains low but variable. A key observation to dispel a misconception: brown petals are not a reliable sign of cold injury. Terminal shoot growth is underway, and varieties in bloom have reached the timing for Kudos application. Pear buds are sizing, so consider post-bloom insect control and upcoming fruitlet thinning once temperatures rise. Fire blight blossom blight risk remains low for now, though trees will be vulnerable until petal fall. The window for blossom thinning is quickly closing. Many thanks to the Orchard Outlook Committee for their continued contributions.



Table of Contents:


Weather
  • 2026 Degree Day Accumulations
  • Frost Events and Blossom Assessment Update
  • Apple Buds
  • Pear and Stone Fruit Buds
  • Apple - Scab
  • Apple - Powdery Mildew
  • Fire Blight Prevention and Shoot Blight Management
  • Apple and Pear - Fire Blight Blossom Blight
  • Apple - Calyx/Blossom End Rot
  • Apple - Postbloom Insects (Advance Notice)
  • Stone Fruit - Postbloom Insects
  • Pear - Postbloom Insects

Thinning

  • Apple Blossom Thinning (Last Chance!)
  • Apple Fruitlet Thinning (Advance Notice)
  • Pear Fruitlet Thinning (Soon!)
  • Suckers
  • Grafting
  • Mowing
  • Root Pruning
  • Pruning and Training
  • Weed Management
  • Wild Apple Trees
  • Nursery Trees

Pest Management Guide



  

Weather


2026 Degree Day Accumulations

This year pulls ahead of last year in the head-to-head race! The cumulative degree days are ahead of the 5- and 10-year averages (Figure 1). Development stages are now similar or slightly ahead of this same time last year. Precipitation is above-average this month but is occurring in concentrated, heavy-rainfall events (data not shown).


Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to May 26 for the past 17 seasons. Provided by Harrison Wright (AAFC Plant Physiology).
  • Approximately 8% more plant development heat units compared to the 5-year average, and 18% more compared to the 10-year average.
  • Approximately 2% more plant development heat units compared to 2025, and 4% more compared with 2024.
  • Approximately 15% more insect development heat units compared to the 5-year average, and 28% more compared to the 10-year average.


Frost Events and Blossom Assessment Update

We experienced three consecutive frost events over the last week in the Valley:
  • Friday, May 22: Lowest temperature recorded in North Medford at -1.0 °C
  • Saturday, May 23: Coldest in Aylesford at -2.0 °C (approximately 15-30 minutes at this low, with temperatures remaining below zero for about 4 hours)
  • Sunday, May 24: Lowest temperature in Aylesford at -1.2 °C
There has been some confusion circulating regarding signs of frost injury. It is important to clarify that brown petals are not a reliable indicator of cold damage to the developing flower bud (Figure 2). Petals might have experienced frost on their extremities, but petals typically brown with age anyway. The only accurate way to assess frost injury is by dissecting buds and examining internal tissue.

Overall, the level of damage appears to be low, though slightly higher than anticipated based on the recorded temperatures. In most cases, damage should not exceed 10%.

When we say that flowers can tolerate temperatures down to -2.2C (for 30 minutes), it is general guidance. But as we know in the natural environment, variability is evident:
  • Low-lying blocks and tree bottoms are most susceptible and warrant a check-in
  • Older blossoms like king blossoms are more vulnerable than earlier-stage buds like side blossoms
  • Varietal differences are evident, with some cultivars exhibiting greater tolerance
  • Duration of below-zero temperatures played a role in the extent of impact
Encouragingly, no damage was observed during field checks in Grafton, Woodville, and Kentville (Middle Dyke). However, there have been reports of localized injury in low-lying areas of Aylesford and Berwick.

Continue to monitor vulnerable sites as conditions and bud stages evolve. Cut flowers in half vertically from the tip to the base. Damaged buds have a distinct dark brown discolouration in the ovary.

Figure 2: Brown petals are NOT a reliable indicator of cold damage to the developing flower bud. Flowers in this photo are all healthy. A flower cluster with brown petals (left) when dissected vertically shows healthy green tissue (right) and no cold injury. Photos taken yesterday on May 25, 2026.



    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 Idared buds were at early petal fall, and both Honeycrisp and Ambrosia were at full bloom (Figure 3). Much of the growth occurred about a week ago during the above-average heat and has slowed during the below-average cool weather.

    A few more observations from the committee:
    • There is plenty of bloom on one-year-old wood that is not typical. This might be a stress response related to the drought the previous year. It may produce more rattail bloom that usual and lengthen the risk of fire blight blossom blight.
    • As a general statement, the bloom is not a snowball bloom but the number of blossoms appears to be above-average. 
    • Varieties prone to protracted bloom like Gala are definitely protracted during this year's cold spell.
    Figure 3: Bud development in an early region on Middle Dyke Road in Kentville on May 25. Shown from left to right: Idared, Honeycrisp, Ambrosia.

    If you want to target the early timing for Apogee/Kudos of 2.5 cm, the stage has been reached for varieties that are in bloom according to my observations (Figure 4). Terminal shoots on Idared measured 5-6 cm with about 8 leaves/shoot, Honeycrisp measured 4 cm with 6 leaves/shoot, and Ambrosia 3-4 cm with 6 leaves/shoot. The measurements are similar to or slightly behind last year. Please note that as soon as terminal growth begins it progresses quickly.

    Figure 4: Terminal shoot growth in an early region in Greenwich on May 25. Shown from left to right: Idared, Honeycrisp, Ambrosia.

    Pear and Stone Fruit Buds

    Yesterday on May 25 at an early region in Greenwich, the pear buds were at petal fall to early fruit sizing. Peach/nectarine was at early shuck split depending on the variety, and European plum was at early shuck split (Figure 5). At the Kentville Research and Development Centre, the sweet cherries are at shuck fall.

    Figure 5: Bud development on May 25. Shown from left to right: An early region in Greenwich with pear, peach/nectarine, and European plum.



    Diseases


    Apple – Scab


    Table 1: Apple scab infection events in Kentville from May 19 to May 26, 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.

    • If a wetting event was not observed on May 19, then the wetting event on May 25 would have released 54.9% of the spore load.

    Recommendations:

    • 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.
    • Primary spores are still present and primary infection events are still a risk. By this coming Sunday, ascospore maturity is forecast to reach 97.8%.
    • Ascospores are maturing at a rate of 0.6-2.6% per day, where higher rates occur on warm days.
    • Do not apply captan within 7-14 days of an oil such as Agral 90 (worse if applied after oil that preconditions leaves).
    • Folpan/Follow should NOT be applied between tight cluster and 30 days after petal fall to avoid fruit russeting.


    Apple – Powdery Mildew


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

    Recommendations:

    • Conditions seemed conducive last week for powdery mildew infection of new leaves. Time will tell if infections occurred and efficacy of protectants.
    • If one of the typical pre bloom applications was missed, the powdery mildew products may be applied starting again at petal fall before a period of dry weather.
    • 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 and Shoot Blight Management


    Recommendations:

    • 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.
    • Even if bacterial EIP populations are low, do not pinch flowers on young trees when tissues are wet. Pinching causes open wounds like a trauma event and bacteria are transported from cankers to wounds in wet weather.
    • Apogee/Kudos (prohexadione calcium) suppress shoot blight. Apogee/Kudos is first applied at 2.5-7.5 cm of shoot growth, which has been reached on varieties in bloom.
      • Please note that the product Apogee is discontinued by BASF. Kudos is another product with the same active ingredient and will remain available.
      • The product takes 10 days to become active so for the maximum effect on fire blight suppression it should be applied before fire blight symptoms appear. Early application might even thicken cell walls of the flower pedicels giving some added protection from blossom blight.
      • When Apogee/Kudos are applied after 10 cm of new shoot growth, the vegetative growth reduction is less but the product will still slow fire blight progression.
      • The product is not systemic so good coverage with high water volume is required.
      • Include Agral 90 at 500 mL per 1000 L of water. Do not exceed this amount of surfactant. If applying Agral 90 there may be a risk of burn if using Captan.
      • Apogee should also be applied with spray grade ammonium sulphate (AMS) in an equal 1:1 ratio with the amount of Apogee used (e.g. 500 g Apogee = 500 g or 0.5 L of ammonium sulphate). This is not the blossom thinning product ammonium thiosulphate (ATS)!
      • Use low rates on young apple trees to avoid delaying growth too much.
      • Some disadvantages of using prohexadione calcium for consecutive years are shortened fruiting branches and when used repeatedly on Gala the retention of fruit set can contribute to smaller fruit size.


    Apple and Pear – Fire Blight Blossom Blight

    Bacteria multiply rapidly in warm temperatures, especially when occurring over consecutive days. The Maryblyt model criteria is used to predict blossom blight infections. Periods with high fire blight bacterial populations are defined by Maryblyt as having an Epiphytic Infection Potential (EIP) greater than 100 - representing 100% of the bacteria load needed to cause infection.

    Blossom Blight Risk
    • Based on the current forecast, the temperature is NOT conducive to the build up of bacteria on flowers this week. Therefore, wetting events are not forecast to trigger blossom blight infections in the short term forecast. The EIP value that represents bacterial growth on flowers is forecast to vary around 0 to 24 this week, meaning there is a low chance of infection even if all other infection factors are present (flowers, wetting, average temperature). Stay tuned in case conditions change.
    • Cooler temperatures have also slowed flower development. As long as blossoms remain open, the risk period for blossom blight persists, and we have not yet moved beyond this critical window.
      If you would like to join the alert contact list, please let me know or sign up online
    • Ideally, you will monitor your own farm-specific situation with PomeBlight using a selected weather station. The user account and PomeBlight tool are free. Follow my 17-minute Quickstart video or Quickstart PDF document.
    • Contact me if you have ANY questions!


    Apple  Calyx/Blossom End Rot


    Recommendations:

    • Infections occur when weather conditions are warm (15 to 25°C) and moist during bloom and shortly after bloom. 
    • The only product with activity on calyx/blossom end rot is captan applied during full bloom. If applying Streptomycin with Agral 90 there is a risk of burn if using captan. Prioritize fire blight over blossom end rot.
    • Infections can occur in problem blocks as the pathogen can last in the soil for several years. The disease is most common on Paulared, Delicious, Cortland, Honeycrisp and McIntosh.
    • Keeping grass and dandelions mowed will allow the soil to dry and reduce the environmental conditions for spore ejection. Other broadleaf weeds are also a host of this disease so weed control prevents the build up of this pathogen.



    Insects


    BE RESPONSIBLE FOR POLLINATORS – DO NOT SPRAY INSECTICIDES DURING BLOOM!
    • Fungicide, antibiotic, and growth regulator sprays are best applied early morning or late evening when bees are not actively foraging. Be aware that dandelion blooms are open until about dusk.


    Apple - Postbloom Insects (Advance Notice)

    Choose post-bloom insecticides according to the pest complex on your scouting report. Insects might include the caterpillar complex, stinging bugs (mullein bug), white apple leafhopper, green and rosy apple aphids, and curculio.

    Refer to the 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. 

    Recommendations:

    • If you have not already treated for rosy apple aphid, be aware that they thrive in cool and wet weather because their predators are suppressed. For those of you that have treated, it's great to be on top of the issue!
    • Stinging bugs and white apple leafhopper hatch around the bloom period and trees should be checked around petal fall for their presence. 
      • Stinging bugs are checked using limb tap samples when the nymphs are very small. 
      • Leafhoppers can be found feeding on the underside of leaves and they will move forward or backward. Leafhopper nymphs are found on cluster leaves close to the main trunk or large branches, not on terminal shoots. Leafhoppers are often controlled by Sevin insecticide when used as a thinner.
    • Codling moth are not active in these cool temperatures but warm evenings will eventually encourage their flight. Organic apple growers should have traps in place and consider the timing of mating disruption for codling moth. When using Isomate-CM/OFM for codling moth mating disruption, have the ‘twist ties’ placed in the orchard blocks by petal fall (prior to the start of male moth flight).


    Stone Fruit - Postbloom Insects

    Plum curculio is a weevil that begins laying eggs in stone fruit at shuck fall. Mated females will deposit their eggs in the developing fruit leaving the characteristic crescent-shaped scar. Activity of PC is increased in temperatures above 16°C so low temperatures in the forecast for later this week might decrease their activity.

    Recommendations:

    • Be aware of bee toxicity warnings on pesticide labels and take precautions while nearby crops are in bloom.
    • Note that pyrethroids are best used at moderate temperatures (20°C or less) and lose efficacy at around 25°C.
    • Plum Curculio
      • Treatment for PC should be applied at petal fall before shuck split to obtain optimal control. A second application is usually needed about 10 days later.
      • The insecticides available for managing plum curculio include Malathion, Pounce, Assail (Neonicotinoid) and Exirel (Diamide). The neonicotinoids kill plum curculio on contact, and they are also systemic so they deter egg laying and feeding. Their systemic activity will also kill eggs and larvae that are present in the fruit.
      • Plum curculio will target apples if they are nearby.
    • Monitor for green peach aphids and black cherry aphid.
    • Tarnished plant bug and stinging bugs cause catfacing of peaches. 
      • This stinging takes place around shuck split/fall. Apply one to two applications of one of the pyrethroids Up-cyde, Ambush, or Pounce listed in the Stone Fruit Pest Guide for peaches. Repeat treatment in 5-7 days if additional stings are detected. (Matador was cancelled from registration in peaches.)


    Pear - Postbloom Insects

    • If you are planning to use Agri-Mek + Oil for pear psylla control, it is best to apply it at petal fall or ideally within 2 weeks. Agri-Mek has better residual control when applied to young tissues because of rapid penetration into leaves. 
      • Do not apply Agri-Mek with any bloom around as this product is highly toxic to bees. 
      • Do not use Captan/Maestro as a fungicide for pear scab within 14 days of Agri-Mek + Oil. 
      • Do not use MaxCel in close proximity to AgriMek because the oil will increase thinning activity.
      • Minecto Pro (Abamectin and Cyantraniliprole) is registered for control of pear psylla with the same recommended application time.
    • Petal fall is the ideal treatment timing for winter moth and fruit worm in pear. Treatment should be based on need determined by monitoring. 
    • Apple curculio is difficult to monitor for and its presence often is not observed until damage on fruitlets shows up. Treatments for this pest should go on when pears have reached petal fall. Use of one of the products registered for plum curculio as it should also control apple curculio. The pyrethroid Up-Cyde is likely most effective and there are other options including Minecto Pro, Exirel, and Harvanta. (Up-cyde is in fact registered for pear and I just realized it is missing from our spray guide).




    Thinning


    Apple Blossom Thinning (Last Chance!)

    It often seems that just when blossom thinning should be a straightforward task, it proves to be anything but. Blossom thinning is inherently unpredictable at this stage of bud development due to the many variables and uncertainties involved. The window for effective ATS application is narrowing as flower fertilization progresses. As a general statement, I suspect today and early tomorrow are the last opportunity. Here are thoughts that have been discussed recently:

    Advantages:
    • There is currently a low chance of fire blight blossom blight infections.
    • King flowers that opened during the heat might have been fertilized well before the side flowers the opened during cool weather.
    • ATS product activity is not reduced in cold temperatures.
    • Blossom thinning is an early opportunity to reduce the crop load on trees that were severely drought stressed last year.

    Challenges:
    • Some growers noted reduced bee activity over the weekend and questioned whether flowers were adequately pollinated at the time. However, honeybees from managed hives were likely still quite active. It is also worth noting that even under the poorer pollination conditions experienced last season, the final crop was largely unaffected because adequate pollination occurred.
    • There is a risk of foliar injury in slow drying conditions.
    • This year the rattail bloom is very delayed. Disregard the rattail bloom when assessing for the application timing of 100% bloom. Unopened flowers will be unaffected by the ATS, but they are too out of sync with the rest of blossoms to target.
    • The effect of last year's drought on the strength of flower buds is unknown.
    If your assessment of the abundance and uniformity of blossoms in a block varies for the top and bottom of the tree, consider directing the blossom spray where there is a higher density of flowers.

    The greatest benefits of blossom thinning are on small fruited varieties like Gala and Ambrosia where there is an opportunity to increase fruit size through early crop load reduction. Do not apply ammonium thiosulphate (ATS) to varieties that are prone to russet. 

    Remember, ATS is NOT recommended for defruiting young trees. In order to eliminate all blossoms, the ATS would need to be applied multiple times to target flowers that open at successive times. The frequent number of applications would increase the risk of foliar spray injury. The leaves of young trees are also very tender.


    Apple Fruitlet Thinning (Advance Notice)


    General Comments:
    • The timing of chemical thinning is based on the average size of the king fruitlet. The size of the side fruitlets is irrelevant. After petal fall, fruitlets typically grow about 1 mm each day in average temperatures. Chemical thinning occurs when king fruit are 5 to 18 mm in diameter and is most effective from 7-12 mm. 

    Product Overviews:

    Sevin XLR
    • Does not overthin so it is mild and reliable.
    • Undissolved Sevin remains active. Damp and drizzly weather that keeps tissue wet but does not wash off product results in more thinning.
    • Often combined with Fruitone for a synergistic effect resulting in more thinning than either product used alone.
    • Temperatures at application should be above 17°C.
    • Note that the PHI for Sevin is 75 days and this may be challenging for early varieties like Paula Red. The REI is 0.5-17 days depending on the activity.
    • When using Sevin in high density orchard do not exceed 3.22 L of product/ha/year. In low density orchard do not exceed 2.15 L of product/ha/year. Sevin is a thinner but note that it is also an insecticide and care should be taken to avoid contact with bees.

    Fruitone L
    • Strong thinner that is very effective in Nova Scotia and is rate-responsive. Higher rates thin more.
    • Unabsorbed residue on leaves is inactivated by sunlight. Slow drying conditions cause more absorption. Therefore, nighttime applications are usually more effective.
    • Temperatures at application should be above 16°C.

    MaxCel/Cilis Plus
    • Product is most likely effective when weather conditions cause a carbohydrate deficit. The thinning effectiveness has been limited in Nova Scotia and it may be because in many years the trees are not stressed during chemical thinner application.
    • This product can be used to increase fruit size (20g/fruit) beyond the influence of thinning by stimulating cell division but the timing matters. When applied at 10-15 mm, it increases fruit weight 80% of the time. Earlier timings are less reliable.
    • Temperatures at application should be above 18°C.
    Brevis (NEW)
    • Temporarily reduces carbohydrate production that leads to carbohydrate stress and causes the tree to drop fruit during resource competition.
    • It is a strong thinner that is rate-responsive. Adjust rates up or down depending on carbohydrate status (warm and cloudy thins easier than cool and sunny).
    • Apply when air temperatures are between 10°C and 29°C and delay application if temperature will exceed 29°C within five days of application. 
    • Young trees experience more aggressive thinning.
    • Combining Brevis with other fruit thinners creates a risk of overthinning.
    • High humidity before and after Brevis will improve uptake and efficacy.
    Accede
    • Product has activity at up to 25 mm fruitlet diameter but should be targeted at 18 mm.
    • Do not apply if temperatures will exceed 30°C on the day of application and for the following three days due to inactivity.
    • Direct 80% of the spray into the upper 2/3 of the tree canopy.
    • Use the adjuvant Agral 90 at the higher rate of 0.125% v/v.

      Recommendations:

      • Research has demonstrated that there is a recommended crop load associated with trunk diameters of apple trees in high density systems that are under eight years old. 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 is more appropriate.
      • During the thinning window I will comment on the suspected carbohydrate status of the trees. 
      • The optimal temperature for thinner activity is between 21-24°C. In cooler temperatures the thinning activity is less and in warmer temperatures the thinning activity is more.
      • Have a block with trees on and off? Thin according to trees with the heaviest fruit set. Trees with less flowers are less likely to thin anyway because holding onto well-supplied fruitlets.
      • Varieties prone to biennial bearing that had a low crop load last year should be thinned adequately and early enough this year to enable bud initiation (for Honeycrisp this is within 45 days after bloom).

      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 fruit/cm² , a Honeycrisp tree with a 2" trunk diameter would have 122 fruit.


      Pear Fruitlet Thinning (Soon!)

      • The Maxcel and Cilis Plus thinning window is 8-14 mm and early treatments are most effective.
      • Brevis is a new thinner that is registered for use from late petal fall until 16-18 mm. 
        • Avoid applying to trees less than 4 years old. 
        • Do not add any adjuvants that increase droplet spreading or penetration. 
        • Do not spray on wet leaves. 
        • Apply when air temperatures are between 10°C and 29°C and delay application if temperature will exceed 29°C within five days of application. 
        • Avoid drift to plum and cherry trees.



      Horticulture


      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.

      Grafting

      • Bark is slipping.
      • The local business Maple Grove Nursery made a video about top working young trees. The video is available on their website called, “Reworking Young Orchard Trees (slow motion)” https://www.maplegrovenursery.ca/grafting-supplies
      • 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.

      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.

      Root Pruning

      • If you are considering root pruning to reduce excessive vigour, the window of timing is from bloom and up to two weeks later. An article from Michigan State was recommended by a local grower.
      • Consider the effect of the drought last year and whether the treatment would be too aggressive on trees.


      Pruning and Training

      • 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

      • 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 requires daytime highs of 10°C-15°C and activity is best when applied from noon to 6 PM.
        • The pre harvest interval for 2,4-D is 80 days that would be challenging for early varieties like Paula Red. 
      • 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. 
        • 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.

      Wild Apple Trees

      • Wild apple trees harbour pests, in particular apple maggot, that can then spread to nearby orchards. Now that wild apple trees are in bloom, it’s a good time to flag trees on your own property so that you can find them later in the season for removal.

      Nursery Trees

      • Treat for tarnished plant bug and green aphids.
      • Consider staking soon to prevent blowouts. Even if not tied, the rod acts as a physical barrier to mechanical injury.
      • 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!


      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, Danny Davison, Larry Lutz, Joan Hebb, Ian Willick, Suzanne Blatt, Mathew Vankoughnett, Heather Rand, Shawkat Ali, and Colin Hirtle.

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

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