Orchard Outlook Newsletter Vol. 24, No 3

Tuesday, April 30, 2024

Today's newsletter reviews the conditions of the latest rainfall with regard to apple scab risk and powdery mildew is discussed because the risk period will begin soon. If freezing temperatures are no longer forecast then this week could be a good opportunity to apply oil for mites. There are a few new notes about weed management and you are invited to a Growing Good Growers tailgate meeting about weeds on Wednesday, May 1. We review horticulture practices including notes on planting this early. Thanks to the ongoing commitment of the Orchard Outlook Committee members.

Table of Contents:

  • 2024 Degree Day Accumulations
  • Soil Temperature
  • Apple Buds
  • Pear and Stone Fruit Buds
  • Apple - Scab
  • Apple - Powdery Mildew
  • Fire Blight Sanitation
  • European Red Mite

Weed Management

  • General
  • Notching for Blind Wood
  • Pruning
  • Fertilizing
  • Liming
  • Nursery Trees
  • Planting Trees
  • Windbreaks

Events and Notices

  • Growing Good Growers Tailgate Session
  • Marbicon Inc. / Jim Jotcham Pesticide Exam Preparation Courses
  • Perennia Food Ventures Program Now Open
  • Resilient Agriculture Landscape Program

Online Pest Management Guide



2024 Degree Day Accumulations

Over the last week there have been slow gains in degree days. The degree day accumulations beginning on March 1 are now essentially equal to the 5-year average (Figure 1). April temperatures have been an overall average of 5.6°C even though throughout the month the observed temperatures have sometimes been above typical maximum temperatures and below typical minimum temperatures. There were several occurrences of temperatures well below zero.
Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to April 29 for the past 17 seasons. Provided by Jeff Franklin (AAFC).
  • Approximately 2% more plant development heat units compared to the 5-year average, and 11% more compared to the 10-year average.
  • Approximately 10% more plant development heat units compared to 2023, and 1% less compared with 2022.
  • Approximately 8% less insect development heat units compared to the 5-year average, and 9% less compared to the 10-year average.

Soil Temperature

The soil temperature this year is above the 10-year average but it is similar to what we've observed in recent years (Figure 2).  Likely the warm soil temperature is attributed to less than average rainfall. Kentville recorded 54 mm of rain for the month of April compared to a 25-year average of 81 mm.

Typically new root growth occurs when soil temperature reaches around 9°C to 10°C. Temperatures ideal for root growth are expected in the near future as air temperatures continue to rise. The start of root activity would be an ideal time to apply granular fertilizer for immediate uptake.
Figure 2: Soil temperatures at 35 cm depth at the Kentville Research Station from 2020 to 2024. The current year is shown in red. Provided by Jeff Franklin (AAFC).

Bud Development

Apple Buds

An early region on Middle Dyke Road in the Kentville area is monitored to guide this newsletter. Yesterday on April 29, the Idared buds were at late half-inch green, Honeycrisp was at half-inch green and Ambrosia was at quarter-inch green (Figure 3).

Figure 3: Bud development in an early region on Middle Dyke Road in Kentville on April 29. Shown from left to right: Idared, Honeycrisp, Ambrosia.

Pear and Stone Fruit Buds

Yesterday on April 29 at an early region in Greenwich, the pear buds were beginning bud burst, peach was at late quarter-inch green, and European plum was at green tip/bud burst (Figure 4).

Figure 4: Bud development in an early region in Greenwich on April 29. Shown from left to right: pear, peach, and European plum.


Apple – Scab

Table 1: Apple scab infection events in Kentville from April 23 to April 30, 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 Saturday, April 15th. 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.


  • We could get into the nitty gritty details but the takeaway message is that tissues should be covered with fungicides prior to wetting events. The decision is yours about whether you now need to follow up with a fungicide if you were caught without one. There were many variables with this most recent wetting, such as:
    • The exact timing of leaf drying depends on microclimates, regions, and varieties. The risk is present because ascospores were mature and present for release. Let's not overthink it.
    • Leaf wetness sensors should be used for guidance only. They often become wet before leaves and dry sooner than leaves. Observe leaf tissue to determine when it becomes dry (Figure 5).
    • The only way to be sure that plant tissues are safe is to maintain regular fungicide protection when new tissue grows. 
    • Remember, you are not getting a week's worth of coverage if leaves are expanding and fungicide products do not move with the new growth.
  • Some of you may have been lured into a false sense of safety when the forecast was only a 30% chance of rain and then were greeted with puddles on Monday morning. If you apply Mancozeb products then it may provide kickback activity for up to 48 hrs after Monday morning if average temperatures are around 6°C. Buran provides post-infection activity of up to 90 hrs. Likely there is not enough leaf area present for the uptake of systemic products.
  • According to the forecast, ascospores are expected to mature at a rate of about 1% per day and by next Sunday 8.5% of ascospores are expected to mature and be available for release (seasonal total of 13%).
  • 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.
  • 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.
  • Remember that Manzate (mancozeb) products may be applied 4 times/ha/year, the re-treatment interval is 7 days, the REI for hand thinning is 35 days (12 hrs for all other activities), and the PHI is now 77 days.
  • If you plan to use oil for European Red Mite control, Captan should be avoided within 7-14 days of an oil application.
Figure 5: When did leaves dry off on Monday? Do not rely on only leaf wetness sensors and be sure to check leaf tissues. This is a magnified photo of an Idared bud on Monday, April 29 at 2:30 PM where a pool of water still sat on the leaf. Overcast conditions without wind led to slow leaf drying times.

Apple – Powdery Mildew

Typically, conidia are released around the tight cluster stage. Powdery mildew infections can be expected when conditions are warm (10-25°C), humid and dry.


  • As opposed to scab, powdery mildew protection should be applied prior to a period of warm and dry weather when infections are expected. Do not apply a product for powdery mildew before a heavy rain is expected because:
    • The product will wash off.
    • Powdery mildew spores will not germinate on a wet leaf surface. 
    • Rain removes powdery mildew spores in the air and destroys spore-producing structures.
  • Application of a protectant mildew fungicide at tight cluster prevents primary infections of leaf clusters. Timely application early in the season will reduce the risk of secondary infections later. 
  • 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.
  • Practice resistance management:
    • Powdery mildew: Group Ms do not have activity on powdery mildew so they will not help prevent powdery mildew resistance development. Products in the groups 3, 7 and 11 are registered for control of PM. Resistance to group 11 products was reported in a survey in 2013. Therefore, whenever the remaining groups 3 & 7 are used, careful consideration must be given to rotating the groups to slow resistance development. Avoid more than two consecutive applications of a single group.
    • Scab: Although Group 3 fungicides Nova and Fullback are also labeled for apple scab, they are not expected to provide control because of resistance in the local scab population. Another product is required for scab protection.

Research Note: I am very happy to share that project work with NSFGA funded through the cost-shared NSDA and SCAP programs will be occurring this year. Perennia will be doing the field work to meet the following objectives. The project aims to identify fungicide resistance of groups 3, 7, and 11 products. On-farm trials at two sites will evaluate FIVE new conventional and biological products that have the potential to improve local management programs. At the farm trials, we will also monitor infection risk according to a decision support tool using on-farm weather stations to refine application timing. Stay tuned!!

Fire Blight Sanitation

Typically the ooze begins to appear between tight cluster and early pink. Initially the ooze is a watery light tan that darkens to amber. When the canker blight bacteria are active, water sprout shoots close to cankers will wilt. 


  • Cankers are visible now before they become hidden by this year's foliage. Scout for cankers now.
  • If in doubt, take it out! No cankers are helpful and they harbour diseases. If you need a second opinion, I can take a look. Cankers are especially risky in young orchards because they harbour the bacteria for new blossom infections that give bacteria rapid access to the leader of the tree. Consider completely removing young trees that have cankers.
  • Copper can be applied to nonbearing trees and processing varieties where fruit russet is not a concern.
  • When ooze is active, 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.
  • Be cautious when applying post-emergent herbicides to prevent injury to young trees. 


European Red Mite

A delayed dormant oil is effective at managing European red mite if monitoring indicates a treatable overwintering egg population. The oil is most effective when applied around egg hatch (typically around tight cluster and before pink) but if practical it may be applied earlier. 

European red mite eggs overwinter in the cracks on buds and spurs so adequate water volume is needed to reach all of the crevices. The oil treatment is not effective for rust mite or two-spotted spider mite.

If freezing temperatures are no longer in the forecast, this week might be a good opportunity to apply oil. Avoid oil if freezing temperatures will occur within 48 hrs and no captan within 7-14 days. Oil should not be applied to young trees at less than 3 years old, and the risk on varieties with Delicious parentage (Ambrosia, Gala) increases after tight cluster.

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.


  • Please note that a new herbicide called Beloukha was added to the weed control guide. It is a group 26 contact herbicide with the active ingredient Pelargonic acid. The product is not registered organic in Canada. Beloukha also has a product registration for sucker control in apples.
  • See below for information on a Growing Good Growers tailgate meeting about weeds occurring tomorrow on Wednesday, May 1 at 11 AM.
  • If you are preparing the ground for planting, note that a pre-plant glyphosate application should be made at least 3 days before tillage. This is especially important to target perennial plants like quack grass and especially in cool temperatures.
  • Consider painting the trunks of newly planted trees white to prevent herbicide injury. Use a water-based white latex paint that may be diluted 50% with water.
  • Most residual herbicides need about 1/2" of rainfall within 7 to 14 days of application to deliver product to the germination zone and to activate the chemical by putting it in solution. 
  • 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 emergence herbicides are best applied on warm and sunny days. Glyphosate and 2,4-D require daytime highs of 10°C-15°C after a night above 3°C to have good activity.



  • Remove tree guards because otherwise they can trap moisture and encourage disease. 

Notching for Blind Wood

  • Notching and applying plant growth regulators (Promalin and MaxCel) is best done from green tip and up until bloom time. The ideal time is at the stage of half-inch green.
  • Please note that the success rate of inducing a branch depends on the age of the planting. Applying a mist of plant growth regulators to the notched area can increase the success rate, namely for older plantings of up to 7 years of age.
  • Notching is preferred over scoring (Figure 6). Scoring can oftentimes heal over and you lose the effect.
  • The plant growth regulators work in cooler temperatures but warm temperatures at the time of application increase the response. For more information, see an article by MSU Extension.
Figure 6: Notching trees above a paradormant bud removes the cambium and disrupts the flow of auxin. Doing so allows the buds to break dormancy.


  • Plan ahead and watch re-entry intervals for pruning activities. 
  • Ensure that youngest blocks are pruned first so growth is directed into desirable leader and terminal extension. Prioritize high value trees and then return to low value areas. Consider prioritizing pruning in fire blight blocks to finish prior to tight cluster when cankers begin oozing.
  • Pruning may be delayed for vigorous Ambrosia to reduce its vigour.
  • Mature blocks can be pruned later and are best when pruned prior to bloom.
  • A handout for farm workers 'The Fundamentals of Pruning' was published this year.


  • Bud break to bloom is the ideal time for granular fertilizer application to maximize tree growth. 
  • If leaf and soil samples show that phosphorus and potassium are adequate there is no need to apply phosphorus and potash. Granular formulations with 0.3 boron are encouraged for sandy soils.
  • If Honeycrisp is on the rootstock G.41 then potassium additions are discouraged.
  • Target 10-16 inches of new growth on bearing trees each year. More growth is a sign of excessive nitrogen.


  • Lime soils prior to planting an orchard with rates according to your soil report. Early spring is an option but fall can be a more practical time to apply lime to a new site and lengthen the time for acidity to become neutralized.
  • Orchard maintenance with surface applied lime twill take a number of years to adjust pH of the soil profile so it is best to apply annually or biannually where needed. If soil testing for pH, measure during the same time each year (August) as pH can change over the growing season. 
  • The provincial limestone trucking assistance program is open.

Nursery Trees

  • Rootstocks that were chip or t-budded last year may have buds pushing. Cutting rootstock tops early can help to prevent the rootstock from overpowering the new buds which often happens with Geneva rootstocks. If using M26 rootstock and tbuds, consider removing the root suckers slowly to avoid flooding the scion bud.
  • Rods may also be put into place early to avoid knocking off buds if done at a later timing.
  • 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.
  • Remember to document the quality of purchased nursery trees with pictures and notes. Did trees dry out? Any signs of disease (cankers, crown gall)? How do the roots look (rinse and take a photo)? Notify the appropriate people of issues you notice. Record the date of planting. An issue that shows up after planting is much easier to diagnose or prevent given this information.

Planting Trees

  • In most cases, the earlier a tree can be planted into friable soil the better. Conditions appear to be good right now for settling the soil around trees. There are likely fewer risks in planting early than late. However, if you are concerned that moisture is lacking, consider installing drip tape. Temperatures for root growth are right around the corner and the forecast for precipitation is unreliable.
  • A new report has now been published by Perennia to summarize local research on, "Developing knowledge-based strategies to manage plant parasitic nematodes in Nova Scotia apple orchards."
  • Avoid letting trees dry out. About 40% of trees can die from drying out, and surviving trees grow slowly. Survivors of 15-minute dry winds recover by year 3. Survivors of 45-minute drying winds still don't grow well by year 3.
  • Bundles of trees sitting in water awaiting planting can asphyxiate, especially in stagnant water and/or warmish water.
  • The length of the rootstock that is above ground level will influence tree growth. Tree size diminishes as the rootstock portion above ground increases. Trees should be planted so that the graft unions are at a uniform height of 8 to 10 cm above the soil line.
  • Wait for a settling rain before applying a residual herbicide to young plantings.
  • Remember the importance of soil preparation. Remove old roots and work to get a good soil tilth without sods and clods especially in the top 15 cm of soil.
  • When trees are first planted they need a high level of soil phosphorus because roots are too poorly developed to forage for it. If phosphate is needed, diammonium phosphate (DAP) can be banded in furrow and incorporated. There is no need to apply phosphorus if a soil test shows P2O5 to be high, such as on land with a history of manure application.


Events and Notices

Growing Good Growers Tailgate Session

We hope that you can join us for the next Growing Good Growers tailgate session hosted by NSFGA and Perennia. These pop-up sessions are meant to offer the space to discuss questions during the season and will offer learning opportunities from one another.

The Growing Good Growers tailgate session will be held at CAP Farms on Wednesday, May 1 at 11 AM. The topic is weed management in young orchards including some weed identification and discussion about pre emergence and post emergence herbicides. For this session we will be joined by Sonny Murray with Perennia. Please bring your thoughts and experiences on weed management including herbicide products and weeds of concern. Please contact me for the address if you did not already receive the email invite (I will not post the address online).

There is no need to RVSP, and we encourage you to bring your own coffee and snacks. Everyone is welcome to attend!

Marbicon Inc. / Jim Jotcham Pesticide Exam Preparation Courses

Marbicon Inc. / Jim Jotcham is offering another round of in-person exam-preparation courses (T2380). 
5 recertification points are available (you can only get credit for T2380 once).
The following locations are confirmed to date, with possible additional courses pending demand.
May 14 Tues – Berwick – Berwick Legion Hall, 232 Main St.
May 16 Thurs – Truro – Douglas St Recreation Centre, 40 Douglas St.
May 21 Tues – New Germany - Anglican Church Hall, 5311 Hwy 10.

The full course, preparing for the exam (all pesticide applicator categories), is $125.
Doors open at about 8:30. Instruction starts at 9:00. Expect to be done around 4:00-4:30.
For only 5.0 recertification points (T2380), the fee is $110 and finished by around 3:15 pm.
A manual is provided. Bring a pen or pencil. Food & drink is not offered. Bring your own or go buy it.

NOTE: Pesticide exams are normally written online, NOT at this course.
Contact NS Environment for further details on writing the exam.
A course is not required before challenging the pesticide exam, but it usually helps.

HST is included in the above prices.
Cash or cheques (payable to Marbicon Inc) or e-transfer (marbicon[at]eastlink.ca).
If paying by e-Transfer, please add a message (for who and for which course).
Pay at the door or by corporate/government purchase order.
Sorry, no Visa, MC, or Debit.

Contact Jim Jotcham at marbicon[at]eastlink.ca or at 902-538-7101 for more details and/or to pre-register.

Perennia Food Ventures Program Now Open

The Food Ventures program is now open and accepting applications for the 2024/25 year! This program provides financial support for the acceleration of innovative and safe Nova Scotia local products to market using Perennia’s food safety and product development services.

Nova Scotia registered farms and agri-food and beverage businesses can apply for cost-shared funding for Perennia services. The Food Ventures Program also provides technical support and educational resources

NEW FOR 2024-25 Businesses with gross annual income between $1,500 and $15,000 are now eligible for Food Ventures Program funding to help them reach new markets. Please see the Program Guidelines for more information.

The current intake period for application is open until November 30, 2024. Learn more about the program eligibility requirements and how to apply on the website!

Resilient Agricultural Landscape Program

The Resilient Agricultural Landscape Program helps to improve the environmental resiliency of agricultural landscapes by accelerating the adoption of on-farm land use and management practices that maximize benefits for the environment and society. Buffers and shelterbelts are listed in the program guidelines for 100% of the establishment costs up to $1,500/acre for creating or widening buffers. The maximum assistance is on a case-by-case basis. The application is due June 30, 2024. For more details, visit the NSDA Program page.

Online Pest Management Guide

Beginning this year, all of the pest management guides are available from an online tool. On the tool you will find guides for organic and conventional apples, pears, peaches/nectarines, plums, and sour/sweet cherries. You can search and filter the information and/or print. To help you navigate the guide, we have developed a brief tutorial video as well as a how to use guide.

The apple and pear guide have been fully reviewed. The stone fruit guides are currently under review. I will post the growth regulator guide soon. This year is a transition year as Perennia has migrated all of the information to a new format and this tool will continue to improve as we actively work on it. Please stay tuned.

This Orchard Outlook has been published with the input of the Orchard Outlook Committee including this week's participants: Larry Lutz, Suzanne Blatt, Danny Davison, Ian Willick, Joan Hebb, and Dustin MacLean.

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

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