Orchard Outlook Newsletter Vol. 22, No 3

Tuesday, April 26, 2022

This newsletter focuses on early season disease management including the progression of apple scab and how to spot fire blight cankers. With the soil heating up, we consider what's needed for nematode sampling. And we review horticulture practices including weed control and reminders for planting. Thanks to the ongoing commitment of the Orchard Outlook Committee members.

Table of Contents:

  • 2022 Degree Day Accumulations
  • Soil Temperature

  • Apple - Scab
  • Apple - Fire Blight Prevention
  • European Red Mite
  • Nematode (Pre-plant samples)

Weed Management

  • Pruning
  • Fertilizing
  • Liming
  • Planting
  • On-farm Nursery

Pest Management Guides 2022

Events and Notices

  • NSDA Soil and Water Samples



2022 Degree Day Accumulations

The past week's accumulation of degree days was slightly below seasonal but cumulative totals are still above average (Figure 1). For the month of April, temperatures have been close to the 10-year trend.

Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1st to April 24th for the past 17 seasons. Provided by Jeff Franklin (AAFC).
  • Approximately 18% more plant development heat units compared to the 5-year average, and 9% more compared to the 10-year average.
  • Approximately 27% less plant development heat units compared to 2021, and 90% more compared with 2020.
  • Approximately 12% less insect development heat units compared to the 5-year average, and 27% less compared to the 10-year average.

Soil Temperature

For those of you waiting for spring fumigation or spring nematode sampling, the temperature of interest is 10°C. Currently, the temperature at 35 cm deep is around 8°C (Figure 2, red line) and the upcoming rain will likely have a slight cooling effect. The soil temperature is relatively warm compared with recent years. Typically 10°C is reached in early to mid-May.
Figure 2: Soil temperatures at 35 cm depth at the Kentville Research Station from 2017 to 2022. Provided by Jeff Franklin (AAFC).

Bud Development

An early region on Middle Dyke Road in the Kentville area is monitored to guide this newsletter. Yesterday on April 25th, the Idared buds were at 1/4 inch green, and Honeycrisp and Ambrosia were at green tip (Figure 2).

Figure 2: Bud development in an early region on Middle Dyke Road in Kentville on April 25th. Shown from left to right: Idared, Honeycrisp, Ambrosia.

Orchard Outlook committee members reported that Honeycrisp, McIntosh, and Cortland in the Morristown area ranged from 1/4 inch green to green tip. Gravenstein and Jonagold were at 1/2 inch green. Pear was at the stage of bud burst. Plum was at the green cluster stage.


Apple – Scab

Table 1: Apple scab infection events in Kentville from April 19 to April 26, based on the Modified Mills Table. 

1 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.
2 Assuming a green tip date of Sunday, April 17th. Please use this as a guide because microclimates will cause conditions to vary on individual farms.
3 All forecasts are estimates. Observe forecasts daily for more accurate predictions.
Note: The environmental conditions for an infection are listed in the Modified Mills Table.

Variable wetting also occurred on April 21 and 22 but at an estimated 7 hours of wetness at 7.9°C it was not sufficient to cause infection (minimum 16 hours under these conditions).


  • Apply a protectant fungicide to green tissue prior to an infection event and reapply on a 7-day interval, with a shorter interval after wet weather (cumulative 1-2” rain) or rapid tissue growth.
  • Vigilant protection of primary scab will prevent the challenges that come with chasing secondary scab. Secondary scab will be increasingly challenging with recent product restrictions.
  • Always tank mix single site fungicides with a group M for resistance management.
  • 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.

Apple – Fire Blight Prevention

Blossom blight symptoms are relatively easy to spot as the dying leaves contrast the healthy surrounding foliage, but the canker symptoms are a little more mysterious. When cankers are not removed, they're a source of bacteria for infection at blossom time. There are many different types of cankers (ie. European canker, anthracnose, etc.) so let's take a look specifically at fire blight cankers. 

Dormant fire blight cankers are a sunken area of bark that can be black to almost purple in colour. The bark might also be cracked or peeling but it does not encircle a branch like the ring-shaped cracks of European canker. The fire blight cankers are often associated with nearby branches that were killed last year. 

When temperatures warm up, the bacteria will begin to multiply and ooze from cankers. Initially the ooze is a watery light tan that darkens to amber. Typically the ooze begins to appear between tight cluster and early pink at which point pruning practices should be done on dry days, especially in high risk blocks. When the canker blight bacteria are active, water sprout shoots close to cankers will wilt. 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.

Figure 3: Fire blight canker showing purple to black bark, sunken tissue and cracks. Photo shared by committee member Joan Hebb, Scotian Gold.


  • If you haven't yet had a chance to apply copper, the window is shortening for fresh fruit application. If copper is applied later than green tip, residues that persist on fruitlets can cause russetting. Processing varieties where russet is tolerable can be treated later as well as nonbearing trees. Copper is most effective in blocks that had fire blight cankers in the previous two seasons. 
  • A fixed copper product such as Copper Spray Fungicide (50% copper oxychloride) is recommended because it is resistant to being washed off by rain. Cumulative rainfall of 100 mm will wash away most of the product, which is why it is applied no earlier than green tip. 
  • Copper can be applied as a tank mix with 0.5% by volume (5 L in 1000 L) dormant oil to increase adherence. Apply in a high water volume to cover plant surfaces. Do not use dormant oil within 14 days of Captan or within 48 hours of freezing temperature. A half rate of an EBDC can be included as extra protection for apple scab.


European Red Mite

To be most effective, oil application for European red mite should be targeted close to egg hatch – around tight cluster and before pink. Avoid oil if freezing temperatures will occur within 48 hrs and no captan within 7-14 days. 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.

Nematode (pre-plant samples)

Root and soil samples are best collected in the spring (May-June) or during the fall (September-October), both of which avoid the heat or drought conditions in summer. Soil temperatures at sampling should be above 10°C for adequate nematode presence in the upper soil levels. Soil temperatures are not yet warm enough but they should be soon.

Keep in mind that nematodes are killed over the winter so the carrying capacity of the site is best determined in fall. However, spring samples can be used to indicate nematode presence. 

Nematodes are unevenly dispersed in open fields so the sample should be made up of subsamples. Sample in a Z pattern, taking a soil core every 10-25 paces and changing direction. Sample to 20 cm deep and remove the top 2 cm of soil. Each soil sample should represent no more than 2.5 ha. Mix the soil, take the required sample size, and store it in the fridge.

The root lesion nematode is the biggest concern for apple growers. A threshold is difficult to pinpoint because a tree's tolerance to nematodes depends on it's overall health, but typically 40-100 root lesion nematodes/100 g of soil is enough to have an influence.

Recent on-farm research led by Perennia in the Valley aims to explore pre- and post-plant management options where nematode populations are at concerning levels. Pre-plant cover crops of interest include pearl millet, sorghum-sudangrass, and brown mustard. For post-plant management, the product Velum Prime is recently registered but it is applied through chemigation and would be best applied during active root growth in spring. 

Weed Management

Studies have shown maintaining weed free strips from bud break to 30-days after full bloom has the greatest impact on tree growth and yield. Timely herbicide application will ensure you make the most of the weed free window. Weeds are still small and post-emerge and residuals should have good impact when applied in the right weather conditions.


The forecast rain will likely contribute to a flush of weed growth but weeds are still relatively small. Management soon after the rainy period is still an opportunity to target small weeds early in the season.

Residual Herbicides
  • Residual herbicides such as Chateau, Alion and others offer a much longer weed control period than post-emergent products including Ignite and Glyphosate. Note the differences in the application directions for Chateau and Alion and refer to the labels for more detailed information:
    • Chateau can be applied to young trees. Chateau should not be applied after budbreak unless application equipment is shielded to prevent crop injury. 
    • On the other hand, Alion can be applied only to mature orchards with trees established for 3 growing seasons. Alion can be applied anytime throughout the growing season.
  • Authority is a good product but it does not have a lot of grass control so rotate with other products to avoid shifting toward more grass population. 
  • Note that residual herbicides can damage single tree replacements. 
  • 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.
  • If weeds are already present, add a post-emerge to a residual herbicide to achieve control. 

Post-Emerge Herbicides 
  • Applying 2,4-D in temperatures below 10°C has historically been ineffective. 
  • Applying Ignite when leaves are wet is also relatively ineffective.
  • Unfortunately, this year there are widespread shortages of herbicides, in particular glyphosate and glufosinate. Reduce the reliance on post-emerge products by starting clean with residual herbicides.  Treat emerged weeds when they are small and succulent.



  • If pruning is delayed, plan a strategy to get the most value for your time. Prioritize young blocks and high value varieties and then return to low value areas.
  • Ensure that youngest blocks are pruned first so growth is directed into desirable leader and terminal extension. Prune early to encourage vigour or delay pruning to remove vigour.
  • Mature blocks can be pruned later and are best when pruned prior to bloom.


  • Bud break to bloom is the ideal time for granular fertilizer application to maximize tree growth.


  • Lime especially if a site is being planted this year. When applied in spring the lime works best when applied as soon as possible to get the product working in the top layer of soil. 
  • Surface applied lime will 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 as pH can change over the growing season. 
  • The provincial limestone trucking assistance program is open.


  • If you fumigated last fall, remember to practice tillage within the same direction as fumigated rows and not across. Tillage across rows would mix fumigated soil in the tree row with non-fumigated soil in the laneway.
  • If fumigating in the spring, remember the importance of soil preparation to get the most out of the fumigant. Remove old roots and work to get a good soil tilth without sods and clods especially in the top 15 cm of soil.
  • If growing your own trees, criticize their quality and don't plan to plant 100% of the trees. Planting small (<4 ft), weak trees will delay production. Trees are typically small for a reason and will continue to be weak trees. Commercial nurseries grade their trees and build in the cost of discarded trees so the same approach is recommended for on-farm nurseries. Tree losses of at least 10% are common.

On-Farm Nursery

  • 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. 

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.
As we look to the future, we really want your feedback on how you access the guides, as well as some things we are considering when sharing the information to make it easier for you to use. If you can please take 2 minutes to complete this short survey for us that would be very helpful and much appreciated.

Events and Notices

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

NSDA Soil and Water Samples

Message from NSDA: Regional offices are accepting soil and water samples for the lab. We are pleased to return this service for the farming community. Please note this does not include water sampling services for the general public. Individuals with those samples should continue to ship or deliver directly to the lab.

As we roll out this service again there are a few changes that will be utilized:

Water Sample Day is TUESDAY – Water samples will only be accepted at the regional offices between 8:30 to noon each Tuesday. If samples are required on other days, individuals must ship or deliver directly to the lab.

Soil Samples will be shipped on Tuesdays with the water and as needed depending on the volume of samples received. If sample results are time sensitive - please drop off before noon on Tuesdays for shipping with water samples or ship or deliver directly to the lab.

IMPORTANT – No cash payments will be accepted

In Antigonish and Kentville payment for samples can be made by credit/debt machine, cheque or billed to your account with the lab. (Cheques to be made out to Nova Scotia Department of Agriculture)

In Sydney, Cornwallis, and Lunenburg - you will need to have an account set up with the lab or include a cheque to send to the lab with the sample - no cash or debit/credit service is available.

Please contact Ross (902-521-5409) to ensure availability before delivering samples to the office Lunenburg.

IMPORTANT – Kentville Agricultural Centre – Under current protocols only visitors by appointment are allowed to drop off samples or meet staff in Kentville. Please call Nicole at 902-679-6021 to arrange a drop off time for your samples. Reminder that masks are mandatory at the Kentville Agricultural Centre.

To set up an account with Laboratory Services please contact the Lab at: (902) 893-7444 or your regional office can assist your in setting up the account. If you have questions, please contact the AEC at your regional office. 

This Orchard Outlook has been published with the input of the Orchard Outlook Committee including this week's participants: Jeff Wentzell, Dr. Suzanne Blatt, Jeff Franklin, Joan Hebb, Colin Hirtle, Dr. Mathew Vankoughnett, Dustin McLean, Danny Davison, Dr. Vicky Levesque, Keith Fuller, and Dr. Ian Willick.

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

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