First Newsletter of 2025!
The Orchard Outlook newsletter will now be published every Tuesday on a regular weekly schedule during the main management season. In this first newsletter we review winter weather to find that in general the temperatures were reasonable. We discuss green tip predictions, and prepare for early season diseases and insects. To help with herbicide programs, the weed management options for different planting ages are listed but will be discussed in more detail at an upcoming tailgate meeting on April 17.
Familiar faces gathered this morning for the first meeting of the Orchard Outlook Committee that informs this newsletter. Please give a warm welcome to our volunteer contributors:
- AAFC - Jeff Franklin, Harrison Wright, Ian Willick, and Suzanne Blatt
- Lutz Family Farm - Larry Lutz
- Scotian Gold - Danny Davison and Ariana Willick
- NSDA - Colin Hirtle
- There are even more committee members and our weekly contributors will be listed at the end of each newsletter to recognize their contribution to industry.
Table of Contents:
- Winter Weather Review
- 2025 Degree Day Accumulations
- Cumulative Precipitation
- Green Tip Prediction
- Bud Observations
- Apple - Scab
- Stone Fruit - Black Knot
- Stone Fruit - Peach Leaf Curl
- Delayed Dormant Oil - Cautions and Considerations
- Scale Insects
- Post-emergence Herbicides
- Pre-emergence Residual Herbicides
- General
- Pruning
- Fertilizing
- Liming
- Growing Good Growers Tailgate Meeting - April 17
Weather
Winter Weather Review
The Environment Canada weather station in Kentville is used for comparison because historical data is available. The average monthly temperatures in Kentville for this past season are shown in red in Figure 1. The average monthly temperatures in January and February were colder than the 5- and 10-year averages. However, in March the story reversed and the average monthly temperature was warmer than historically.
Figure 1: Average monthly temperatures from December through March for the past three winters, and for 5- and 10-year averages at Kentville AAFC.
However, the on-farm Davis weather stations are more representative of Valley microclimates and they did record cold temperatures during an inversion event on February 10. The Melvern Square station recorded -22.3°C. If minor damage (10%) is observed in peach buds then it can be explained by this event. Having said that, damage is unlikely because the winter was consistently cold and plant hardiness should have been acceptable. Peach buds should be able to tolerate temperatures down to -23°C.
Figure 2: Extreme minimum monthly temperatures from December through March for the past three winters, and for 5- and 10-year averages at Kentville AAFC.
2025 Degree Day Accumulations
Figure 3: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to April 14 for the past 17 seasons. Provided by Jeff Franklin (AAFC Plant Physiology).
- Approximately 6% more plant development heat units compared to the 5-year average, and 27% more compared to the 10-year average.
- Approximately 3% less plant development heat units compared to 2024, and 63% more compared with 2023.
- Approximately 33% more insect development heat units compared to the 5-year average, and 58% more compared to the 10-year average.
Cumulative Precipitation
So far in 2025, the early season precipitation totals are slightly below average.
Bud Development
Green Tip Prediction
Over the last 15 years, the first green tip date of apple recorded in Orchard Outlook has ranged anywhere from April 6 (2010) to May 6 (2015). The average green tip date is April 20. In recent years, Jeff Franklin has helped to estimate green tip dates based on degree day accumulation. This year the prediction based on the weather forecast is for early varieties to reach bud break on April 23 in Kentville. The date may be sooner if warmer-than-forecast weather is observed.Bud Observations
Yesterday on April 14, I checked the bud stage of several different fruit trees in the Greenwich area. The Honeycrisp buds were at silver tip, peach/nectarine were at late swollen bud, pear was dormant, and European plum was dormant (Figure 4).
Figure 4: Bud development in an early region in Greenwich on April 14. Shown from left to right: Honeycrisp, peach/nectarine, pear, and European plum.
Diseases
Apple – Scab
Beginning at green tip, apple tissues are susceptible to infection from the fungus that causes apple scab, Venturia inaequalis. The environmental conditions for an infection are listed in the Modified Mills Table. Primary infections are caused by ascospores present in the leaf litter and infections develop on spur leaves, terminal shoots, and young fruitlets. Ascospore maturity is aligned with bud development so that mature spores are ready to be released when buds show green tissue. If not controlled, primary infections will create spores that generate secondary infections for the rest of the season. The best approach to fruit protection is to control primary scab.
Recommendations:
- Apple scab spores are mature but if bud development is not yet at the green tip stage, it is not at risk of apple scab infection.
- Monitor for green tissue on early varieties that signals the need to apply a protectant fungicide prior to the first infection event. Protection will then need to be reapplied on a 7-day interval, with a shorter interval after wet weather (cumulative 1-2” rain) or rapid tissue growth.
- Remember that mancozeb products (manzate, penncozeb) may be applied only 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 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.
Stone Fruit – Black Knot
Recommendations:
- Prune limbs 15 cm beyond the knot and destroy knots (burn or flail mow).
- Complete knot removal before the new shoots that develop in late bloom are exposed to new infection risk.
Stone Fruit – Peach Leaf Curl
Apart from a spring protectant fungicide I don't have new recommendations to offer here. However, there is some new information and work underway that I learned at OFVC this past winter that might be of interest. Although not actionable right now, it might come into play in future management approaches.
- Work in Ontario shows that the foliage is susceptible to peach leaf curl infections for up to 40 days after bud break, not just at bud break.
- A guest speaker from Italy, Irene Salotti, described the occurrence of peach leaf curl infections. Early infections (green tip to petal fall) are severe and are responsible for causing complete defoliation. Middle infections (6th to 12th leaf) cause symptoms of leaf margins and can cause partial deformation. Late infections (after 12th leaf) cause leaf margins to become moderately deformed in small sections. Fruit infections can occur during petal fall to 3-4 weeks later when there is a heavy rain event (>15 mm) and temperatures below 18°C. The onset of symptoms is about 10-30 days after infection.
- A protectant fungicide applied before bud break may provide adequate protection during a dry spring but it is possible to observe more infections in an unusually wet year if the protectant is washed off before the infection period is complete.
- High volume sprays of 1000 L/ha work the best for protectant fungicide.
- There is some ongoing research work in Ontario that appears promising for fungicides with activity on peach leaf curl. Stay tuned!
Insects
Delayed Dormant Oil - Cautions and Considerations
As delayed dormant oil season approaches, consider the following.
CAUTIONS: DELAYED DORMANT OIL:
- When green tissue is present, do not use dormant oil 48 hours before or after freezing temperature. Oil that is applied before freezing temperatures breaks down and adheres to the plant tissues unevenly instead of the target insects. Also if the oil and water mixture freezes before it dries then the green tissue can be injured.
- 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.
- Consider the greater water volumes needed for large canopy trees that have not been pruned yet versus trees that have been pruned.
- At OFVC this past winter there was an interesting presentation by Brett Blaauw about using horticultural oils on stone fruit trees before and after pruning for control of scale insects. In the stone fruit example, a water volume of 1,870 L/ha was required pre-pruning for adequate coverage of the extra limbs and control of scale. On pruned trees the water volume of 935 L/ha was adequate. This example is not directly applicable to apple but suggests the importance of using oil with water volumes that provide thorough coverage of the bark that is appropriate for the orchard situation.
Scale Insects
The best time to target scale is ideally just before the tree breaks dormancy or with a delayed dormant spray of oil by green tip. Scale cannot develop resistance to the smothering action of the dormant oil so the oil can help to slow resistance to insecticides. Also, the spring oil application is more effective than insecticides at reducing the overall scale population. After green tip, the scale insects start building their waxy coating so the oil does not affect them after they have built their defences.
- The timing for targeting scale is not similarly effective for mites. The timing for mites is geared toward egg hatch after bud break and closer to tight cluster. Target your oil application for the more important pest issue.
Weed Management
Join us at the Growing Good Growers meeting on April 17 for a group discussion! See the events section below for details. I will have a handout with herbicide summaries available.
To get out of the cycle of trying to manage large weeds with post-emergent herbicides, think about pre-emergent/residual herbicides as filling windows of time. Most residual products will give about 4-6 weeks of weed control. Use residual herbicides through periods of high weed germination like in spring. Post-emergent herbicides help with clean up when weeds are small.
Recommendations:
Post-Emergence Herbicides
- Weeds emerging after treatment are not controlled (not residual).
- Treat early at the 3-6 leaf stage for optimum weed control. Young leaves have a less well-developed cuticle and absorb more. The risk of crop damage is also minimized.
- Options according to tree age:
- Preplant:
- It is very valuable to use glyphosate to clean up tough perennials before planting. Weeds need to be actively growing and the glyphosate should be applied at least 3 days before tillage when temperatures are at least 10°C day/3°C night.
- Planting year:
- Largely Reglone for grasses, Venture for grass, Lontrel for spot spraying listed perennials, Basagran for broadleaf
- Established >1yr:
- Similar to planting year plus Ignite for broadleaf and grass
- Mature >3 yr:
- Similar to young tree options plus 2,4-D and glyphosate
- 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.
- Applying Ignite when leaves are wet is relatively ineffective.
- In the USA, there are concerns about Ignite causing bark cracking. The specific risks are yet to be defined but just be cautious that Ignite is not sprayed onto or drifts onto young tree bark.
- Perennial weeds may be targeted in spring when new perennial plants are at the seedling stage. Other timings are spot sprays at the early flowering stage or during fall re-growth after a minor frost. Glyphosate and group 4 products are systemic and work on certain perennial plants.
Pre-emergence Residual Herbicides
- 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.
- Residual herbicides offer a much longer weed control period than post-emergent products. Residual herbicides kill viable weed seeds and then the undisturbed soil surface will be weed-free even after the chemical degrades.
- Options according to tree age:
- Planting year:
- Chateau for broadleaf + Prowl H2O for added grass control
- Simazine products for broadleaf and some grasses
- Sinbar for broadleaf and some grasses.
- Established >1yr:
- Similar to planting year plus additional broadleaf options Authority and Sandea.
- Dual II Magnum offers some grass control.
- Mature >3 yr:
- Similar to young tree options plus products Alion and metribuzin (Sencor) with broadleaf and grass activity. Alion is preferably applied in the fall as it requires a lot of water to become activated.
- Chateau should not be applied after budbreak unless application equipment is shielded to prevent crop injury.
- If you are taking out orchard within the next 2-3 years for replanting, avoid applying residual herbicides. The Alion label says to allow at least 12 months from last application to replanting an orchard.
- Note that residual herbicides can damage single tree replacements because the trees are not yet established for longer than 3 years.
- 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.
Horticulture
General
- Keep ahead of brush because the spraying season will begin soon.
- Remove tree guards to prevent trunk diseases.
- If digging nursery trees, be mindful of the soil moisture. Digging trees too early in wet soil can lead to root damage and soil clumps brought into storage. Trees should be dug before vegetative buds start to push (which happens after established trees have pushed flower buds).
Pruning
- Plan ahead and watch re-entry intervals for pruning activities when fungicide programs begin.
- 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. Cut out cankers, whether fire blight or other diseases.
- Pruning may be delayed closer to bloom 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' is available in English and Spanish.
Fertilizing
- 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 each year. More growth is a sign of excessive nitrogen.
Liming
- 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 will be open soon. A summary of the programs was released last week but they are not yet open for application. When the program opens, early applications will be considered first in line for available funds.
Events and Notices
Growing Good Growers Tailgate Meeting - April 17
The Growing Good Growers tailgate session will be held at Eisses Farm on Thursday, April 17 @ 11am. The topic is weed management 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 programs and weeds of concern. What works and what doesn’t? How are the economics and labour requirements for applications? Let’s continue the conversation from last year!
Please meet us in the orchard across from the house at 1190 Thorpe Road, Northville, NS. There is no need to RVSP, and we encourage you to bring your own coffee and snacks.
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.
Edited by Michelle Cortens, Tree Fruit Specialist
Perennia Food and Agriculture Corp.
Perennia Food and Agriculture Corp.
