Orchard Outlook Newsletter Vol. 22, No 15

Tuesday, August 9, 2022

Today's newsletter has a preharvest focus. Note that heat accumulated so far is above average and may contribute to earlier harvest periods. For late season disease management, fungicides are sorted from longest to shortest preharvest interval with a list of diseases controlled. Leaf and soil nutrient sampling is discussed. Finally, strategies for harvest fruit quality are discussed including speeding or delaying maturity, disorders, and estimating bin requirements. Several events are listed including this week's NSFGA summer orchard tour. See you there!

Table of Contents:

  • 2022 Degree Day Accumulations
  • Mean Temperature
  • Precipitation
  • Reminders about Fungicide Preharvest Intervals (PHI)
  • Apple Storage/Pinpoint Scab
  • Apple - Black Rot
  • Apple - Brooks Spot
  • Apple - Flyspeck and Sooty Blotch
  • Preharvest Management of Apple Storage Rots and Fungi
  • White apple leafhopper
  • Potato leafhopper
  • Apple maggot
  • Spotted wing drosophila (SWD) in stone fruit
  • Leaf Tissue Sampling for Nutrient Analysis
  • Soil Sampling for Nutrient Analysis
  • Preparing for Fumigation
  • Calcium Nutrition
  • Mowing and Weed Control
  • Summer Pruning for Red Colour
  • Harvesting Early with Ethrel (Final Year)
  • Delaying or Synchronizing Maturity with ReTain and Harvista
  • Estimating Bin Requirements
  • Reducing Bruising
  • Considering Watercore
  • Avoiding Internal Browning
  • Consequences of Harvesting too Early

Pest Management Guides 2022

Events and Notices

  • NSFGA Orchard Tour this Thursday! See you there!
  • Field Day - The Dirt on Cover Crops
  • Farm Transition Seminar Series from Farm Credit Canada


2022 Degree Day Accumulations

The cumulative degree days are above the 5 and 10-year averages for base 5°C and 10°C heat units (Figure 1). The totals are running similar to 2010, 2012, 2013, and 2021. The heat accumulated so far may contribute to earlier harvest periods but check your records from similar years for guidance.

Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to August 8 for the past 17 seasons. Provided by Jeff Franklin (AAFC).
  • Approximately 6% more plant development heat units compared to the 5-year average, and 6% more compared to the 10-year average.
  • Approximately 2% more plant development heat units compared to 2021, and 5% more compared with 2020.
  • Approximately 7% more insect development heat units compared to the 5-year average, and 7% more compared to the 10-year average.

Mean Temperature

Jeff Franklin reports that, "temperatures have been consistently above the mean since the middle of July. The high temperatures combined with below average rainfall is creating some drought stress in both annual and perennial crops."
Figure 2: This year's daily mean temperatures relative to the 10 year trend showing above average temperatures since the middle of July. Provided by Jeff Franklin (AAFC).


    Precipitation in July was below average with 36 mm recorded in Kentville. Sites with moisture sensors in sandy loam soils were especially prone to low plant water availability. Bearing trees on lighter soils or in sandy pockets are showing drought stress. Thank goodness for some of the recent rain!

    Figure 3: Precipitation recorded in Kentville in July for the past 10 seasons. Provided by Jeff Franklin (AAFC).

    Late Season Diseases

    Reminders about Fungicide Preharvest Intervals (PHI)

    Table 1: Fungicide products for control of summer diseases listed from longest preharvest interval to shortest preharvest interval. Includes notes about diseases controlled and re-entry intervals (REIs).

    Apple Storage/Pinpoint Scab

    Pinpoint scab results from infections that occur late in the growing season. Small black dots appear as infections on the skin of the apple. In some cases, the fruit infections don’t appear until after the fruit has been placed in storage, however, the infections do occur prior to harvest.


    • Fungicide protection maintained through to early September can help to prevent these late season scab infections and provide some protection against storage rots. Note the risk of summer diseases if spray programs are stretched to the limit. Once the 10-day interval has been reached, it is better to re-apply fungicide protection prior to rainfall/possible infection rather than after. 
    • Late season fungicide treatment is highly recommended in blocks that have leaf and/or fruit scab. Scab lesions that appear to be inactive at this time of the year can become active again in the fall under cool wet weather conditions.
    • Folpet (Folpan/Follow) is considered a cousin to Captan and is similarly a hot product that has the potential to cause fruit russetting. Do not use Folpan close to oil sprays or products containing surfactants. Also, be wary of tank mixes with liquid nutrients that are formulated to maximize uptake.

    Apple  Black Rot

    The black rot fungus infects fruit during warm rains from petal fall to harvest. Captan is an effective protectant for high density orchards that have a history of black rot. However, consider Captan where practical in terms of label restrictions for re-entry intervals. Merivon has activity but group 7 + 11 products should not be used more than 4 times each year. Fungicides would need to be applied prior to the wetting event.

    Apple - Brooks Spot

    Brooks spot is caused by a fungus that creates sunken, dark green lesions on the fruit. It is a minor disease that has been an issue on Honeycrisp in the past. The symptoms of Brooks Spot can resemble lenticel breakdown and bitter pit which are also common on Honeycrisp.

    Apple - Flyspeck and Sooty Blotch

    These summer diseases develop on the surface of the fruit in midsummer until harvest. They are caused by fungi that overwinter in dead twigs and the fungi tend to cause more infections under conditions of moderate temperature, high humidity and rainfall.

    Preharvest Management of Apple Storage Rots and Fungi

    A well-timed preharvest chemical control can go a long way to prevent storage rots. Black rot, flyspeck, sooty blotch and brooks spot are preharvest issues that can infect fruit in the orchard. Fungal spores that land on unprotected fruit can germinate and show up as infections in storage. Fruit with bruises and punctures are even more susceptible to rot, especially when fruit are harvested during a wet period. Blue and gray moulds can invade only damaged fruit. Sooty blotch won’t cause decay but it does shorten fruit storage life by increasing water loss.


    • Monitor precipitation during harvest, especially for late-season varieties. Cumulative rainfall of 25-50 mm washes off fungicide protection.
    • The group 7 & 11 products Pristine and Merivon can be applied up to 5 days before harvest. They are labelled for the control of scab, black rot, flyspeck, and sooty blotch. The short PHI and good activity are especially helpful for protecting apples being placed in long-term storage.
    • Of course, avoid bruising or wounding to prevent infections of blue and gray moulds. Take the time to educate staff on the proper way to handle fruit.


    Insect management programs should be based on grower monitoring and/or scouting reports.

    • White apple leafhopper
      • Nymphs from the second generation appear and cause feeding damage in early August. Insecticides labelled for leafhoppers include Assail/Aceta, Calypso/Theme, Savanto Prime and Exirel.
    • Potato leafhopper
      • The potato leafhopper feeds on the young leaves of terminal shoots leading to yellowing at leaf edges, and cupping that will eventually turn brown. Adults are pale yellow-green and walk sideways whereas the white apple leafhopper is white and moves forward and back.
      • Potato leafhoppers can transmit fire blight. Their presence in young plantings and nurseries is concerning, especially in areas of active fire blight infections.
    • Apple Maggot
      • The economic threshold is 1 maggot fly per orchard on a yellow sticky board. Apply a treatment 7-10 days after the first fly is captured on a yellow sticky board or immediately after a female is captured on a red sphere.
      • Note the different re-entry intervals for hand thinning from longest to shortest: Imidan 30 days, Danitol 23 days, Cormoran 7 days, Assail/Aceta 6 days, Calypso/Theme 12 hr, Exirel 12 hr, Harvanta 12 hr, Vayego 12 hr, and Delegate (suppression) 12 hrs. 
      • Note the preharvest intervals from longest to shortest: Calypso/Theme 30 days, Danitol 16 days, Imidan 14 days, Cormoran 14 days, Assail/Aceta 7 days, Harvanta 7 days, Vayego 7 days, Delegate 7 days, and Exirel 3 days.
      • Clean maggot traps 7 to 10 days after treating a block for maggot and monitor for new trap captures. Retreat if new maggot flies are caught.
      • Significant rainfall will wash off insecticide residues that are needed to ward off apple maggot flies. Re-treatment is required after 10-14 days or cumulative rainfall of 12.5-25 mm (0.5-1 inch). Insecticide residue should generally be maintained through to the end of August.

    Stone Fruit Insects

    • Spotted wing drosophila (SWD) in stone fruit
      • Spotted wing drosophila lay eggs in ripening tender fruit, and larvae may be present at harvest. If monitoring indicates treatment is required, use insecticides weekly. These products rely on contact with spotted wing drosophila adults.
      • Products registered for control of SWD in peach and plum are listed in the Stone Fruit Management Guide. PHI varies widely:
        • longer PHIs for Danitol, Harvanta, and Imidan
        • shorter PHIs for Delegate, Exirel, Entrust and Success


    Leaf Tissue Sampling for Nutrient Analysis

    Nutrient levels in leaf tissues change throughout the growing season. The nutrient analysis for apple tree leaves has historically been done after terminal buds set and recommendations are based on that specific timing (late July to early August in Nova Scotia). Collecting samples prior to or after the specified period may give inaccurate nutrient level readings. Annual fertilizer applications should be based on tissue analysis reports and other factors such as pruning, vegetative growth and anticipated crop load.


    Collect leaves for nutrient analysis after terminal buds set on this season’s extension growth. Complete sampling by mid-August.

    The protocol:
    • A sample usually represents a block of orchard 1 to 2 hectares in size.
    • Sample 10 apple leaves from each of 10 representative trees of the same variety for a total sample size of 100 leaves. Sample from the same trees every year to limit the variation between years. Try marking the tree with spray paint.
    • Collect leaves from the mid-point of the current year’s growth from all sides of the tree.
    • Place the leaf samples in a paper bag.
    • If there are problem areas within the orchard, then sample trees in the areas separately.
    • The leaf sample needs to be submitted as soon as possible after collection in order to obtain an accurate nutrient analysis. If the sample cannot be submitted right away, refrigerate until it can be submitted.
    • Always label samples with the grower or farm name, mailing address, phone number, farm registration number, orchard block name, variety and sample number.
    • Take an accurate sample by reviewing some guidelines on 'How to take a plant tissue test'
    • For fees, contact the lab or your choice.

    Soil Sampling for Nutrient Analysis

    A leaf nutrient test tells you whether a nutrient has been absorbed. A soil analysis, on the other hand, shows what levels are available. If a tree cannot uptake nutrients from adequate soil levels then perhaps your limiting factor is not related to nutrient availability and is more likely related to compaction, nematodes or pathogens affecting the root system. Or more simply, a soil nutrient test could determine a soil nutrient deficiency.


    • Soil samples do not need to be collected on an annual basis but should be collected at least once every three years.
    • Two to four soil cores should be taken at the drip line from each of 10 trees. The soil cores should be mixed and a representative sample placed in a soil box or sealable plastic bag for analysis. 
    • Early August is a good time to sample orchard soil unless the soil is unusually dry or recently leached by heavy rains. If the soil is too dry it is very difficult to extract full 0-15 cm (0-6") soil samples and a better sample will be obtained by waiting until light rain has moistened the topsoil.

    Preparing for Fumigation

    If you want fumigation done this fall contact Danny Davison at Scotian Gold to express your interest. Sites that will be fumigated early this fall need to have the soil prepared to where it is in a seed bed condition. A poorly prepared site could result in the fumigant being ineffective. This means that there should be no large clumps of soil or vegetative matter that will hinder the sealing of the soil surface. Preferably, the fumigation strip should also be deep ripped to bring up roots or stones that may damage the fumigator. 

    Calcium Nutrition

    • Note that nutrient product formulations with calcium may contain boron that would interact poorly with water soluble packaging.
    • Calcium applied at two-week intervals is better than occasional, high-rate applications. 
    • The recommended rate is 4 to 14 pounds of elemental calcium per acre in a season spread over six to eight cover sprays. The percentage of elemental calcium will be listed on the label.
    • 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.
    • Calcium chloride flake (77% Ca) is the most economical Ca material to use but also the highest risk for foliar burn. Apply calcium chloride flake at no more than 4.5 kg per 1000 L of spray solution. 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.

    Mowing and Weed Control

    • Mowing will help to conserve moisture so that it is not transpired by the large surface area of tall weeds and grasses. Mowing and blowing the clippings into the tree row can also help to conserve moisture.
    • Mowing and herbicide strips help to prevent issues with two-spotted spider mite (John Michael Hardman).
    • Maintain good weed control during July and August on young plantings that need to develop vegetative growth. Studies have shown that weed competition during this time can have a significant negative impact on early cropping of young blocks.

    Harvest Fruit Quality

    Summer Pruning for Red Colour

    Vigorous shoot growth in orchards could present a fruit shading problem. Summer pruning could be used to expose the fruit to more sunlight to improve fruit colour. Also, summer pruning controls vigour so it could divert more calcium to fruit. The practice might help reduce the risk of bitter pit. 


    • Summer pruning should be a simple process of making the pruning cuts to one- and two-year old wood. Remove vigorous shoots in the entire canopy but especially at the top.
    • Leave the weaker side laterals to supply the fruit with carbohydrates. If you over prune you could end up reducing fruit size.
    • Avoid leaving short stubs as they will produce two or more shoots next spring.

    Harvesting Early with Ethrel (Final Year)

    The registration of the product Ethrel is changing. The previously approved label is being phased out but it is valid until September 24, 2022. After September 24, Ethrel cannot be applied to bearing fruit trees so this year will be the final opportunity to use Ethrel for hastening fruit maturity for early markets. 

    Delaying or Synchronizing Maturity with ReTain and Harvista


    • ReTain will be discussed at the Aug 11 NSFGA summer orchard tour. See the events section for more detail.
    • As even more new plantings come into bearing, consider the advantages of harvest management tools to help slow fruit maturity as you manage labour resources. 
    • Both ReTain and Harvista can help reduce the incidence of watercore and internal browning by delaying maturity. 
    • The economic return for these products is expected to be greatest with good crop loads, high-value varieties, and good fruit quality.
    • Consider testing ReTain or Harvista on a small block and talk to others who have experience using them.


    ReTain’s active ingredient (aviglycine hydrochloride) inhibits the production of ethylene in plant tissues, delaying fruit maturity. Potential benefits of ReTain include harvest management to delay the maturity in blocks of a single variety, improved fruit size (as fruit hangs longer on the tree), maintenance of firmness, and reduced greasiness and cracking. ReTain can also offer additional benefits including improved storage quality. However, Retain can also slow red colour development. Delays to fruit colour development can be minimized by lowering the rate of application or by delaying the harvest period.


    • Note that the amount of ethylene produced differs by apple variety and so the variety’s response to ReTain will also differ. McIntosh is a high ethylene-producing variety and the full rate is often needed 3 weeks before harvest to slow its maturity. Sensitive varieties like Gala, Jonagold and Honeycrisp produce low ethylene and are more sensitive and thus greatly delayed by full rates of ReTain.
    • ReTain applied 3-4 weeks before harvest will delay the harvest period up to 7 to 10 days.
    • The effectiveness of ReTain is dose-dependent and time-dependent. Later applications and smaller doses have less effect on maturity and colour development.
    • For a multi-pick harvest, ReTain applied 7 to 14 days prior to the anticipated start of the 1st harvest can improve the quality and storage potential of 2nd and later picked apples. First picks will not be affected but later picks will be delayed. Note the PHI of 7 days.
    • Xiameter surfactant is recommended at a concentration of 0.05 to 0.1% (v/v) in the spray tank. To prevent possible spotting on fruit, use the 0.05% (v/v) concentration.
    • ReTain is not a systemic product. Good coverage of both fruit and leaves is important to response.
    • On the label, there is a caution stating that the fruit on heat- and water-stressed trees may not respond to the product.


    Harvista (1-methylcyclopropene) is another product for preharvest management that was registered in 2017. The mode of action is different from Retain because Harvista blocks ethylene action in fruit, even after ethylene has been produced by fruit. Therefore, Harvista can act quickly to slow maturity whereas ReTain requires a timely application to fruit before ethylene production escalates.


    • Harvista can be applied 3 to 21 days before the anticipated harvest and at a higher rate for fruit that are more advanced in maturity and producing plenty of ethylene.
    • Harvista will delay the harvest period up to 7 to 14 days.
    • Typically the product will reduce the number of harvest picks because it helps synchronize the maturation rate.
    • Lower rates are recommended for biocoloured apple varieties to allow colour development to progress. It can delay red colour development on Gala and Ambrosia so apply after colour has developed at close to 3 days before harvest. It also reduces stem splits on Gala.
    • A customized sprayer system is required for Harvista applications.

    Estimating Bin Requirements

    Large apples fill bins a lot quicker than small apples. If fruit in a block are a relatively uniform size, then a little math can help you estimate bin requirements. The crop volume is determined by the number of trees, number of fruit, and fruit size.

    To approximate the number of bins required:
    1. Calculate the number of apples per acre (# trees per acre x avg # apples per tree)
    2. Refer to the table for the # of apples per 17 bu bin of a selected count size
    3. Bins/acre = # of apples per acre / # apples per bin for selected count size

    Table 1: Number of apples of a selected count size to fill a 17 bu bin.

    Example 1: 125 count size
    1. 1000 trees per acre x 60 apples/tree = 60,000 apples/acre
    2. There are 2125 apples per bin of 125 count size.
    3. Bins/acre = 60,000 apples per acre/2125 apples per bin = 28.2 bins/acre

    Example 2: 113 count size
    1. 1000 trees per acre x 60 apples/tree = 60,000 apples/acre
    2. There are 1921 apples per bin of 113 count size.
    3. Bins/acre = 60,000 apples per acre/1921 apples per bin = 31.2 bins

    Reducing Bruising


    • Apples picked after significant rain will bruise more easily than if they’re picked when the soil has a lower moisture capacity. This information might be helpful for varieties especially sensitive to bruising.
    • Let fruit warm up before harvesting. Apples picked in the cool weather of early morning bruise more easily than those picked in the day’s warmth. Generally, susceptibility to bruising decreases gradually from 0 to 15°C.
    • Take the time to educate staff about the proper way to perform harvest activities that reduce bruising. For example, pick the bottom of the tree first, don’t overfill the picking bag, avoid long harnesses that let the bag bump against knees when walking, explain the difference between varieties etc.
    • Re-grade orchard roads prior to harvest to lessen bumps that would jostle fruit being transported in bins.
    • Have an inspector sample fruit from various positions in the bin two times each week and leave at room temperature for 24 hours to check for signs of bruise development.
    • If bins of fruit will sit in the orchard during overnight freezing temperatures, place the bins where they will be shaded from direct morning sun. Direct sun will warm the fruit too quickly and can lead to deep and lasting bruises.

    Considering Watercore

    Watercore is a fruit disorder closely associated with over-mature apples along with several other factors. It happens most frequently in years with high sunshine and lack of cloudy, rainy days. Also, highly coloured and large fruit are most prone to the disorder. Fruit with the disorder have an appearance of water-soaked flesh because the spaces between the cells become concentrated with sugars instead of air. Small signs of watercore can disappear in storage and add sweetness to fruit. However, more serious watercore can reduce gas exchange in the fruit and lead to internal breakdown.


    • Mature fruit are more likely to develop the disorder because as fruit mature the starches are converted to sugars. The sugar solution builds up in the fruit. Blocks that have a history of watercore should be harvested before other blocks.
    • Consider products to delay harvest maturity. Both ReTain and Harvista labels state delayed onset and incidence of watercore.
    Figure 1: An example of watercore symptoms in Honeycrisp from 2018. Note the areas of water-soaked flesh.

    Avoiding Internal Browning

    Internal browning is likely related to carbon dioxide injury. The disorder frequently occurs in overmature and large fruit that have high carbon dioxide concentrations. In particular, fruit harvested late in the harvest window are most susceptible because as fruit mature their ability to diffuse internal carbon dioxide concentrations decreases. The internal carbon dioxide builds up and increases the chance of injury. Consider using products that delay harvest maturity.

    Consequences of Harvesting too Early

    While trying to avoid overmature fruit, avoid the other extreme as well – immature fruit. Picking fruit too early has penalties. Fruit continue to grow as they mature so a 1/4 inch increase in size from 2 3/8 to 2 5/8 can translate into a 35% increase in fruit volume. It takes just as long to pick one large (88 count) apple as it does to pick one small apple (160 count). But it will take half as long to make up a bushel of large apples than small. So picking cost and time required are less for larger fruit. Picking too early can also sacrifice fruit colour and reduce pack out. Immature fruit bruises easily and is subject to scald, shriveling in storage, and poor flavour.

    Pest Management Guides 2022

    All changes new to 2022 are made in red text directly on the guides. The information on all changes was summarized in a blog post on April 8th.

    Events and Notices

    For upcoming events, visit the ‘Events’ tab on the NS Tree Fruit Blog. Specific events will be described here when available.

    NSFGA Orchard Tour this Thursday! See you there!

    August 11th has been selected as the date for the 2022 Summer Orchard Tour. For the full agenda, visit the NSFGA website. The Orchard Tour will begin at Miner’s Marsh in Kentville at 87 Cornwallis Street (behind the Justice Building). There will be ample parking for those wanting to take the bus. They are asking folks to arrive at 8:15AM for introductions and greetings. Buses will be boarded at 9:00AM sharp and return at 4:00 PM. There will be five different orchard stops, with lunch along the way at Northville Farm Heritage Centre. Please complete registration for each person attending the tour from your farm, business, or association to allow them to gauge numbers for both the bus and for the lunch orders.

    Michelle and Emily spent an afternoon mapping out the Orchard Tour route with our gracious hosts! Photo by Emily Lutz, NSFGA.

    Field Day - The Dirt on Cover Crops

    August 23rd from 9:00-12:30 PM
    Brooklyn Corner, NS (Field location will be sent in advance of the day)

    Please join Horticulture Nova Scotia and Perennia Food and Agriculture specialists for a morning of cover crops! Seeding methods, the effects of residual herbicides on cover crop establishment, cover crop species conversations, equipment show-and-tell, brown mustard management strategies, and more! Pesticide points and CCA points will be available. To register for this event, please click here.

    Farm Transition Seminar Series from Farm Credit Canada

    Join Farm Credit Canada for a 9-part virtual event series on farm transition. Hosted by FCC Business Advisors and transition experts, each month will feature a new topic, highlighting a different step in the process.  Registration at their website.

    Can’t attend a live event? No problem – check back to watch the recordings at your convenience!

    • August 9, 2022 – Crunching the numbers: Assessing farm transition financials
    • September 20, 2022 – Value, vision, and goal setting - a farm transition powerhouse
    • October 11, 2022 - Building a farm transition team – how to find the right fit
    • November 8, 2022 - Will and estate planning: The key to any successful farm transition
    • December 13, 2022 - Creating a business plan that fits your farm transition vision
    • January 10 , 2023- Handing over the keys: Transferring knowledge in farm transition
    • February 14, 2023 - Unlock your inner CEO: Leading a successful farm transition
    • March 14, 2023 - Review, revisit, repeat: Keeping your farm transition plan alive

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

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