First Newsletter of 2024!
The Orchard Outlook newsletter will now be published every Tuesday on a regular weekly schedule during the main management season.
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 - Keith Fuller, Jeff Franklin, Harrison Wright, Ian Willick, Suzanne Blatt, and Jill MacDonald
- Lutz Family Farm - Larry Lutz
- Scotian Gold - Joan Hebb and Danny Davison
- Perennia - Dustin MacLean
- Retired AAFC/Consultant - Bob Prange
- NSCC - Matthew Vankoughnett
- 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.
Also, thank you to everyone who completed the survey regarding tree fruit extension this past winter. It is clear that this newsletter is valuable to many and I will use your suggestions and priorities to guide future content.
Table of Contents:
- Winter Weather Review
- 2024 Degree Day Accumulations
- Weather Stations in the Valley
- Apple Buds
- Pear and Stone Fruit Buds
- Apple - Scab
- European Red Mite
- European Fruit Scale
- Pre-emergence Residual Herbicides
- Post-emergence Herbicides
- Pruning
- Fertilizing
- Liming
- On-farm Nursery
- Polar Vortex Recovery Program Phase 2
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. In each month this past winter, the average monthly temperatures were warmer than the 5- and 10-year monthly averages, especially in March.
Figure 1: Average monthly temperatures from December through March for the past three winters, and for 5- and 10-year averages at Kentville AAFC.
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.
2024 Degree Day Accumulations
In addition, soil temperatures are about 2°C above-average (not shown).
Figure 3: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to April 17 for the past 17 seasons. Provided by Jeff Franklin (AAFC Plant Physiology).
- Approximately 18% more plant development heat units compared to the 5-year average, and 33% more compared to the 10-year average.
- Approximately 52% more plant development heat units compared to 2023, and 2% less compared with 2022.
- Approximately 22% more insect development heat units compared to the 5-year average, and 25% more compared to the 10-year average.
Weather Stations in the Valley
Perennia continues to provide technical maintenance of the ten Davis weather stations owned by the Nova Scotia Fruit Growers Association through a contracted service. The maintenance includes replacing sensors, updating firmware, changing batteries, levelling, and cleaning sensors etc. If you are concerned with any readings from a station please contact Michelle.
Notices:
- We are aware that the Grand Pre weather station is not operational. Our technician has been working to resolve the issue but unfortunately the issue is not typical and could not have been anticipated. Our technician is waiting for pricing and parts before advising how to proceed with this unexpected issue.
Bud Development
Apple Buds
An early region on Middle Dyke Road in the Kentville area is monitored to guide this newsletter. Yesterday on April 15, the Idared buds were at green tip, Honeycrisp was at scale separation to early green tip and Ambrosia was at early scale separation (Figure 4). Growth appears to be 4- to 5-days ahead of last year.
Figure 4: Bud development in an early region on Middle Dyke Road in Kentville on April 15. Shown from left to right: Idared, Honeycrisp, Ambrosia.
Pear and Stone Fruit Buds
Yesterday on April 15 at an early region in Greenwich, the pear buds were at swollen bud, peach was at swollen bud, and European plum was at bud burst (Figure 5).
Figure 5: Bud development in an early region in Greenwich on April 15. Shown from left to right: pear, peach, 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:
- If bud development is not yet at the green tip stage, it is not at risk of apple scab infection.
- According to the current forecast, a prolonged wetting period may occur on the weekend and may signal the possibility of this season's first infection event. Monitor the forecast as green tissue could be widespread by then. Assuming a green tip date of April 15, by the weekend about 2% of total ascospores are expected to be mature and available for release.
- Green tissue signals the need to apply a protectant fungicide prior to the first infection event and reapplication 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 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.
Insects
***IMPORTANT NOTE: 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. Please note that there are freezing temperatures currently forecast for the evening of Thursday, April 18.
European Fruit Scale
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 defenses. The scale that are under the waxy coating are the adults that are preparing to give birth to live young. The live young are the active stage known as crawlers. When the crawlers leave the waxy coating they become susceptible to insecticides. Typically the crawlers are active in July in Nova Scotia but they should be monitored for more specific timing.
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 with less effective results. European red mite eggs overwinter in the cracks on buds and spurs so high water volume is needed to reach all of the crevices. The oil treatment is not effective for rust mite or two-spotted spider mite.
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.
Weed Management
Interesting observation: Common chickweed is currently in bloom. If you see common chickweed in bloom in the tree row right now then you have a population of winter annuals that germinated last fall and are currently completing their life cycle to produce seeds that will germinate this coming fall. Treat the winter annual population in the fall to achieve control in early spring.
Recommendations:
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 in Table 1 offer a much longer weed control period than post-emergent products in Table 2. Residual herbicides kill viable weed seeds and then the undisturbed soil surface will be weed-free even after the chemical degrades.
- 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.
- Alion can be applied only to mature orchards with trees established for 3 growing seasons. Alion can be applied anytime throughout the growing season.
- Note that residual herbicides can damage single tree replacements. The Alion label says that individual plants within an orchard may be replanted by removing all treated soil from the transplant hole and refilling with soil that has not been treated.
- 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.
- Chateau and Authority are good products but they do not have a lot of grass control so rotate with other products to avoid shifting toward more grass population. Chateau may be tank mixed with Prowl H2O to widen the weed spectrum for selective control of annual grasses and extend control.
- 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.
Table 1: A list of pre-emergence herbicides registered for use on apple trees. Modified from Kristen Obeid, OMAFRA, 2019.
Post-Emergence Herbicides
- Weeds emerging after treatment are not controlled (no residual).
- Treat early at the 3-6 leaf stage for optimum weed control. Young leaves have a less well-developed cuticle and absorb more. Crop damage is also minimized.
- 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.
- Venture takes about 3 weeks to kill labelled annual and perennial grasses. Growth ceases immediately but the death is slow. Don't use Ignite with Venture because Ignite will burn top growth before Venture kills it. If grasses become tall you may use Ignite to burn the grass down and then during grassy regrowth apply Venture to kill systemically. Wait at least 3 days after Venture before applying an herbicide for broadleaves.
- 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.
Table 2: A list of post-emergence herbicides registered for use on apple trees.
Horticulture
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.
- 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.
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 is open.
On-Farm Nursery
- Trees that overwintered in nurseries are at bud break and will become difficult to handle if tissues grow. Trees are being dug and stored for the short term in a dark room or longer in cold storage. Do not store trees in rooms containing apples because the ethylene gas from fruit will damage tree buds.
- Do not overwater trees in storage.
Events and Notices
Polar Vortex Recovery Program Phase 2
The Polar Vortex Industry Recovery Program Phase 2 is open. The activity period is until April 30, 2024. All of the information is on the Horticulture Nova Scotia website.Online Pest Management Guide
Beginning this year, all of the pest management guides are now 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.
Changes of note for apples in 2024:
- Calypso is due for cancellation and the last date of use is on Dec 31, 2025.
- Many product labels have been updated recently and occasionally there are changes to max applications and new minimum application intervals are stated.
- New tank mix regulation must be fully implemented by Dec 20, 2024. You will notice that new labels either, 1) have a general statement that permits tank mixing, 2) mentions a specific tank mix partner, or 3) has wording to prohibit or limit tank mixing.
- The chemical thinner Accede is registered and will be included in the growth regulator guide.
Edited by Michelle Cortens, Tree Fruit Specialist
Perennia Food and Agriculture Corp.
Perennia Food and Agriculture Corp.
