Today's newsletter reports average king fruitlet diameters on varieties ranging from 15.5 mm to 23.2 mm so there may be a final opportunity for rescue chemical thinning. Some notes are shared on trying the new thinner Accede. Cell division is occurring right now and the forecast heat will help to encourage greater potential fruit size. Please be aware of the week-long risk of fire blight infections on open blossoms in young trees so you can develop a strategy. Information is shared on late codling moth trap captures. Finally, pictures of interesting horticulture observations are shared from the field. Thanks to the ongoing commitment of the Orchard Outlook Committee members.
Table of Contents:
- 2024 Degree Day Accumulations
- Apple Buds
- Pear and Stone Fruit Buds
- Apple - Scab
- Apple - Powdery Mildew
- Fire Blight Prevention
- Apple - Fire Blight Blossom Blight
- Fire Blight - Infection Management
- Apple - Black Rot
- Apple - Brooks Spot
- Apple - Flyspeck and Sooty Blotch
- Apple Insects
- Apple and Pear - Codling Moth
- Apple Fruitlet Thinning
- Defruiting Young Trees
- Pear Hand Thinning
- Peach Hand Thinning
- Notes from the Field
- Cover Crops
- Mowing
- Weed Management
- Pruning and Training
- Nursery Trees
- Marbicon Pesticide Exam Preparation Courses
- Save the Date - NSFGA Summer Tour August 7
- Perennia Webinars: Understanding Alternative Nutrient Amendment
- 2024 Virtual Orchard Meetups Series
Weather
2024 Degree Day Accumulations
The degree day accumulations for base 5°C plant development and base 10°C insect development are still ahead of the 5- and 10-year averages and will likely gain more above-average heat this week (Figure 1). Please note that the graph was last updated on Friday, June 14 because our amazing contributor Jeff is away this week.
Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1 to June 14 for the past 17 seasons. Provided by Jeff Franklin (AAFC).
- Approximately 12% more plant development heat units compared to the 5-year average, and 12% more compared to the 10-year average.
- Approximately 20% more plant development heat units compared to 2023, and equal to 2022.
- Approximately 16% more insect development heat units compared to the 5-year average, and 14% more compared to the 10-year average.
Bud Development
Apple Buds
An early region on Middle Dyke Road in the Kentville area is monitored to guide this newsletter. Yesterday on June 17, ten king fruitlets of each of the following varieties were measured to get a rough average (size of side fruitlets is irrelevant). The Idared measured 23.2 mm (grew 0.9 mm/day), Honeycrisp 17.4 mm (grew 0.8 mm/day), and Ambrosia 15.5 mm (grew 0.8 mm/day) (Figure 2).
Figure 2: Fruit bud development in an early region on Middle Dyke Road in Kentville on June 17. Shown from left to right: Idared, Honeycrisp, and Ambrosia. The king fruitlet is measured to represent fruit stage for thinning and the size of the side fruitlets is irrelevant.
Pear and Stone Fruit Buds
Figure 3: Bud development in an early region in Greenwich on June 17. Shown from left to right: pear, peach, and European plum.
Diseases
Apple – Scab
Recommendations:
- According to the model, total seasonal ascospores matured to 100% on Saturday, June 8 and then a wetting event on June 9 would have released the final primary spores. Models are not completely accurate so wait 2 weeks after ascospores are depleted and when you can assess your incidence of primary apple scab infections. Decisions about whether to lengthen fungicide intervals can be made on June 23.
- Product options at this time of the year:
- Captan may be used as long as it is not applied within 7-14 days of an oil such as Agral 90 (worse if applied after oil that preconditions leaves). The REI for hand thinning fruit in high-density systems is 15 days and in low-density systems it is 24 days. The product has activity on summer diseases. For high density, do not use more than 10 applications per year and for low density do not use more than 2 applications per year. Remember, if using SHARDA CAPTAN 48 the rate equivalent to other captan products is 5 L/ha (2.4 kg of active ingredient). Please note that this liquid format might improve uptake and also increase the risk of leaf injury.
- Allegro may be applied as long as oil has not been applied within 3 days (including Fontelis and Agral 90). The REI is short at 24 hrs.
- Do not apply: Folpan/Follow and Syllit should NOT be applied between tight cluster and 30 days after petal fall to avoid fruit russeting.
- Buran may be considered again. But remember that the product is registered for only suppression of apple scab and must be used post-infection only. Summer disease control is not likely strong.
- Note that single site products in group 3 are not expected to provide control of apple scab due to resistance. For other single site products, check the label for rates required for apple scab control because for Luna Tranquility the high rate is needed unless it is tank mixed with another product for scab control.
- Several of the single site products do not have activity on scab after petal fall (fruit scab). Such products include Fullback, Nova, Cevya, Aprovia, Sercadis, Excalia, Scala, and Vangard.
- Pears: For pear scab, Allegro and mancozeb are NOT registered uses. Captan may be used 2 times for low density and 10 times for high density. Note that for pears, Scala and Luna Tranquility have a 72 day preharvest interval. The registered products are listed in the online guide under Tree Fruit and Pears.
Apple – Powdery Mildew
Powdery mildew infections can be expected when conditions are warm (10-25°C), humid and dry.
Recommendations:
- Protection may continue for 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.
- The forecast of warm and rain-free periods would continue to suggest that this week offers the opportunity for infections to happen.
- If you're using Luna Tranquility for powdery mildew, concurrent activity for scab control is only provided at the high rate. If you're using a full rate of Nova, Fullback or Cevya, no scab activity is expected due to resistance. If using Nova, the water soluble packaging should not be mixed with oil or boron.
- Avoid more than two consecutive applications of products with a group 3, 7, or 11. Powdery mildew resistance to group 11 products was reported in a survey done in 2013 so success is unlikely. Group M products do not have activity on powdery mildew.
- Buran is registered for control of powdery mildew in apples under low to moderate disease pressure and local research is ongoing. Apply with 0.1% Agral 90. This product does not have protectant scab activity so will only provide scab protection post-infection.
Fire Blight Prevention
Recommendations:
- Pruning and training 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.
- Even if bacterial EIP populations are low, do not pinch flowers in wet weather. Pinching causes open wounds like a trauma event and bacteria are transported to wounds in wet weather. Remember that any remaining flowers are susceptible to infection if the EIP becomes high.
Apple – Fire Blight Blossom Blight
Current and Forecast Blossom Blight Risk
- Industry alerts will continue while bloom in young plantings is present.
- An alert was sent on Monday for high risk all week. As stated in the alert, all regions are forecast to exceed the EIP threshold of 100 on open blossoms every day this week. If wetting occurs an infection is expected.
- An antibiotic is forecast to provide protection on only the day of application. In the heat, new flowers open and bacteria grow quickly. Phone me for more details.
- Ideally you can monitor your own farm-specific conditions and improve your management decisions using PomeBlight that was developed for Nova Scotia apple and pear growers.
Recommendations:
- Do not underestimate the risk of infections on late flowers. By the time of late flowers there is already plenty of bacteria established throughout the environment.
- How many blooms per tree is a concern for fire blight? Consider that one blossom per tree is one potential infection per tree. One infection is enough to kill a tree so one infection per tree is too many infections.
- Have a strategy for a week-long risk of infections. You may pinch the flowers on dry days or rely on an antibiotic. If possible, use Kasumin during bloom when conditions allow in order to save streptomycin applications for less-flexible risk periods.
Fire Blight - Infection Management
Symptoms of blossom infections are becoming visible but the incidence has been limited so far. Symptoms might only be showing for early bloom infections.
Recommendations:
- As soon as you find fire blight infections, an application of Apogee/Kudos (prohexadione calcium) can help to suppress the progression of infection that buys you time for cutting it out. Use a lower rate if trees have not filled their space or the full rate if tree growth is not an issue.
- Do not break off branches with fire blight infections as you navigate the orchard. Research shows that the bacteria becomes systemic in the tree because branches are not adequately removed. There are then a high number of new infections and significantly more canker tissue and cankers on structural wood.
- Prune out fire blight infections on young trees in the current year, don't wait for winter.
- Remove fire blight strikes at least 2-4 ft below active infections to remove the leading edge of the bacteria. The younger the tree, the deeper the cut. Being aggressive at the first sign of symptoms will help prevent the re-occurrence of symptoms and the need for continuous cutting back. Repeat tree inspections.
- If you feel confident that you can monitor the formation of a canker on a stub cut for later removal, then a stub cut may be appropriate. A 4-inch stub cut causes a canker to form on the stub before reaching structural wood like the leader of the tree. However, do not forget to remove the stub because otherwise the canker will serve as a source of bacteria. Mark the tree for revisiting.
Apple – Black Rot
Recommendations:
- Based on our limited knowledge, the highest risk of infections is theoretically between petal fall and 4-6 weeks after bloom.
- A 10 hr wetting period at 16°C to 32°C allows infection.
- The optimum temperature for infection is 20°C to 24°C.
- There are few management options to cover such a long risk period. Captan has activity but note the REI for orchard activities. Merivon has activity but this group 7 + 11 product should not be used more than 4 times each year. Folpan has activity but should not be applied until 30 days after petal fall to avoid russet. We do not have a model for black rot infection but protection would need to be targeted prior to wetting and ideal weather conditions.
- The fruit cuticle is sensitive to damage at this stage. Be cautious with spray mixtures (calcium, foliar nutrients).
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. Include a product for cover sprays that is labelled for brooks spot such as Inspire Super and Aprovia Top (or Folpan 30 days after petal fall).
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. Include a product for cover sprays that is labelled for flyspeck and sooty blotch such as Captan, Maestro, Inspire Super, Aprovia Top, Cevya, Allegro, Pristine, and Merivon (or Folpan 30 days after petal fall).
Insects
Apple Insects
Please refer to the petal fall insecticide decision table for a quick overview of your choices for apple trees. Choose insecticides by considering what you are targeting and what the products control. Often your hardest to control pest will determine what you need to use, then check the label of that product for all pests that are also controlled by the product.More Notes:
- Monitor for white apple leafhopper. Sevin XLR applications for thinning in mature blocks will control leafhopper but monitor non-bearing plants for leafhopper. If treatment is required, a neonicotinoid, Sivanto Prime, or Exirel would control leafhopper.
- Monitor for green aphid in young trees and nursery plantings where feeding can disrupt shoot growth. If leaves are curling high, high water volumes are needed for effectiveness.
Apple and Pear: Codling Moth
Degree Day and Treatment Timing Predictions
The biofix dates for this season are June 1 for early and June 5-6 for late regions determined by Erika Bent, APM. Jeff Franklin, AAFC, last ran the degree day model on Friday, June 14 to predict when degree day thresholds will be met for treatments. The predictions have not changed.
Codling Moth Treatment with Rimon
Timing: The treatment timing for Rimon is 80 degree days Celsius from biofix. Suzanne explains that the benefit of targeting the eggs is that they are more exposed. Once the larvae burrows into the fruit the exposure is lower, which could explain why Rimon used later (targeting larvae) is less effective than using it earlier (on eggs).
Prediction: According to the current forecast, the 80 degree day threshold is expected to occur by June 14 for early regions and June 16 for late regions.
Codling Moth Treatment with Egg Hatch Products
Products: Assail, Calypso, Delegate, Intrepid, Altacor, and Exirel
Timing: The treatment timing for egg hatch products is 100 degree days Celsius from biofix.
Prediction: According to the current forecast, the 100 degree day threshold is expected to occur by June 16 for early regions and June 18 for late regions.
Products: Assail, Calypso, Delegate, Intrepid, Altacor, and Exirel
Timing: The treatment timing for egg hatch products is 100 degree days Celsius from biofix.
Prediction: According to the current forecast, the 100 degree day threshold is expected to occur by June 16 for early regions and June 18 for late regions.
Product: Imidan
Caution: All hand thinning activities must be completed prior to application. No hand thinning can occur on trees treated with Imidan.
Timing: Control of codling moth with Imidan is typically slightly later at 140 degree days after biofix.
Prediction: According to the current forecast, the 140 degree day threshold is expected to occur by June 20 for early regions and June 22 for late regions.
The models were run on Friday, June 14 with a degree day threshold of 10 degrees (C) using Kentville weather station data. Stay tuned for updates as the model will be recalculated with changes in the forecast.
Timing: Control of codling moth with Imidan is typically slightly later at 140 degree days after biofix.
Prediction: According to the current forecast, the 140 degree day threshold is expected to occur by June 20 for early regions and June 22 for late regions.
The models were run on Friday, June 14 with a degree day threshold of 10 degrees (C) using Kentville weather station data. Stay tuned for updates as the model will be recalculated with changes in the forecast.
How does the biofix apply in situations with late trap captures?
Anything burrowing into the fruit (like codling moth and European apple sawfly) are timing-specific and while the DD model can give you an idea of when they are at what stage, it really is a challenge to correlate trap captures (tell you the ‘when’ for your site) with the when and what to spray.
This is where the biofix can be helpful (to start the DD model for your site) but can also miss the mark [for some sites]. For example: biofix is set at June 5 this year. That starts the clock ticking for those growers who have catches, but it doesn’t start the clock for growers who have no [or below threshold] catches.
Once a grower starts to catch and has their own ‘biofix’, the clock begins. This is especially true in the case where a grower has interlopers from the neighborhood and thus egg laying will occur later than the 80 DD post-biofix.
Fruitlet Thinning
Apple Fruitlet Thinning
Please note that the timing of chemical thinning is based on the average size of the king fruitlet. The size of the side fruitlets is irrelevant because all of the research is based on the size of the king fruitlet as a timing/development stage. After petal fall, fruitlets typically grow about 1 mm each day in average temperatures. Chemical thinning occurs when king fruit are 5 to 18 mm in diameter and is most effective from 7 to 12 mm.
This year a new thinner called Accede is registered and has activity at up to 25 mm fruitlet diameter but supposedly works best at 18 mm. Product supply is limited but you may wish to try it on a small scale.
Recommendations:
- If rescue thinning is necessary, Accede treatments may be applied to high value varieties this week when they are expected to measure 18-25 mm. Earlier treatments are expected to be most effective.
- The Accede label warns, “Avoid spraying Accede when ambient temperatures exceed 30°C on the day of application and for the following 2-3 days.” We are still learning about this product. There is evidence to suggest that the warm temperatures might give good activity so phone me for details.
- Remember that you can adjust your spray pattern based on fruit set on the top versus bottom of the tree. Usually late in the thinning window the target is excess fruit set in the top of the tree so you may direct your spray.
Defruiting Young Trees
- Defruiting young trees can be accomplished with a combination of Sevin XLR at 2.5 L plus Maxcel/Cilis Plus at 5.0 L per 1000 L of water applied using dilute nozzles to the point of drip. A few litres of oil (10.6 L/1000 L water) can also be added as a spreader sticker to this combination unless the variety is sensitive to oil (avoid Gala, Ambrosia, Golden Delicious, Red Delicious).
- This mixture should cover more than an acre of young trees.
- Apply from petal fall until 8-10 mm. A second application can be done before 18 mm if additional thinning is needed. A second application will likely still miss some fruit so consider that hand thinning may still be required anyway.
- This week's heat would aid in the defruiting activity.
- Choosing to use Fruitone (NAA) in this mixture instead of MaxCel will result in chemical pinch at the terminal bud that stunts growth.
- Using currently available products, the amount of product that would be needed to completely defruit trees in our climate would likely negatively affect tree growth. Therefore, expect that hand thinning will still be required.
Pear Hand Thinning
- On mature trees, if the total crop load is high then reduce the number of fruit per cluster to 1 or 2. During years of light fruit set, leaving 2-3 fruit per cluster will still produce good sized fruit. Space clusters 12-15 cm apart.
Peach Hand Thinning
- Hand thin early-maturing varieties first for increasing the chances of fruit sizing.
- Start thinning after natural drop is clear.
- Space fruit clusters about 15 cm apart.
Horticulture
Notes from the Field
Last week several interesting horticultural observations were pointed out to me in the field that may be of interest. See the Figure 4 images associated with these details:
A) Curling leaves from cluster leaves may be a result of April freezing temperatures.
B) Vineland 1 (V1) rootstock pushes new unwanted shoots on paradormant buds at the base of the tree.
C) Frost heaving that was corrected by hilling with a finger weeder has lead to healthier trees the following season. On heavy soil sites, the lateral roots heave easily. When hilling, make sure the apex of the hill is on the tree line so water moves away from the tree trunk.
D) Symptoms of replant disease may become more apparent in droughty conditions. Trees in the foreground are on non-orchard soil and in the background an old orchard site.
E) G202 rootstock has bark peeling off that may be a lingering effect of the polar vortex.
F) Trees that were pruned prior to the 2023 polar vortex may be less healthy than those pruned after the polar vortex. Some trees still appear to be showing lingering signs of winter injury and eventually collapse.
Figure 4: Observations in the field on the week of June 10, 2024.
Solstice Reminders
- Top dressing is not recommended after the end of June. Late release will prevent trees from hardening off before the winter.
- Around July the trees are storing reserves in the roots for next year’s growth. When they are storing reserves, late glyphosate applications can be damaging if taken up by root suckers and transported to the root system. Avoid the risk by avoiding glyphosate applications after the end of June.
Cover Crops
- Perennia has a series of videos about cover crops by Sonny Murray and Rosalie Gillis-Madden that can be accessed from our website.
- Summer grasses such as pearl millet and sorghum-sudangrass that have been growing in popularity lately can be planted from mid-June until early August.
Mowing
- Keeping the orchard floor cover mowed to minimize dandelion flowers that attract bees, which increases the safety of insecticide applications.
- Mowing and herbicide strips help to prevent issues with two-spotted spider mite (John Michael Hardman).
Weed Management
- Note that 2,4-D has an 80-day PHI.
- 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.
- Create a plan for the whole year. Put on residual products before weeds emerge and use the post-emerge products as backup.
- If using glyphosate alone, consider coarse droplets and low pressure to reduce drift. Use Ignite during hot days in full sun if possible.
- In young plantings, weed control is essential. If newly planted trees have received a settling rain then you may consider a residual herbicide before the next rain.
- Understand and consider using more Venture for grass control in young orchard. Venture is slow to work (2-3 wks) but you can check for activity by removing the flag leaf on treated grass and examining the base of that shoot for rot.
- Add Prowl H2O or Dual II Magnum to improve your grass control spectrum in young orchard. These pre-emerge products won’t work for bluegrass species however.
- Sinbar is good for pre-emerge grasses in young orchard.
- Lontrel is a great post-emergent for vetch, clovers, and sheep sorrel.
- Chateau has activity on Ragweed whereas Authority does not.
Pruning and Training
- Start selecting strong terminals on young trees and remove competing terminals to single the tops if there are no re-entry intervals active.
- Pruning and training practices should be done on dry and sunny days, especially in blocks with high risk of fire blight. Wounds can take about 2 days to heal. Do not work in trees when they are wet from dew.
- Ensure that deer fencing is installed as soon as possible to protect new growth on young trees. Prior to deer fencing, the product Bobbex may be used as a deer repellent but it requires frequent application to new growth and after rainfall.
- Newly planted trees should be pruned for tree structure and supported as early as possible after planting. Prioritize trees that are known to be brittle at the union, including many of the new Geneva rootstocks (G.11, G.41, G.16 etc).
Nursery Trees
- Consider staking to prevent blowouts. Even if not tied, the rod acts as a physical barrier to mechanical injury.
- Treat for tarnished plant bug and green aphids.
- Remove rootstock leaves when they are tender and before shoots become woody.
- For bench grafts, leave some shoots on the rootstock to feed the scion as the callus tissue develops. Locally, rootstock leaves have been stripped when the scion has 8-10 leaves. Early in the season, leave at least an extra scion leader for insurance.
- Remember the importance of weed control in nurseries. Management practices now will impact the outcome of the final tree.
Events and Notices
Marbicon 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 and dates are confirmed.
June 26 Weds – New Germany - Anglican Church Hall, 5311 Hwy 10.
June 27 Thurs – Berwick – Berwick Legion Hall, 232 Main St.
June 28 Fri – Truro – Douglas St Recreation Centre, 40 Douglas St.
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@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@eastlink.ca or at 902-538-7101 for more details and/or to pre-register.
Save the Date - NSFGA Summer Tour August 7
The 2024 NSFGA Summer Orchard tour will be held on Wednesday, August 7th, 2024. This year NSFGA is bringing back the evening portion of the tour and hosting a barbecue chicken dinner, with families welcome to join for an evening meal! A bus will be provided, seats are limited. Registration is not required and the event is free of charge.Events like this are only possible through sponsorship! NSFGA has announced that sponsorship opportunities are now available.
Perennia Webinars: Understanding Alternative Nutrient Amendment
You’re invited to a summer webinar series with local and passionate professionals discussing the world of nutrient amendments that can be used to help producers in transitioning from synthetic nitrogen fertilizer, assist in utilizing resources, and adding nutrient and microbial diversity in agricultural systems through the use of composts, manure, by-products, and more. For more information and to register, visit the Perennia website.
2024 Virtual Orchard Meetups Series
Every Thursday until June 27 at 8:00 PM Atlantic time
Since 2021, the North American Summer Virtual Meetup Program has brought together growers, researchers, extension, and government to have a conversation about important tree fruit topics. Connecting industry leaders across North America, over 20 experts are involved in these 90-minute online forums, interacting with more than 1,000 participants.
The fourth series will focus on "Water Wisdom: Navigating Tree Fruit Production Through Drought and Deluge". Over the past decade, growers have experienced unpredictable rainfall, water availability challenges, droughts and deluges. We want to explore methods for adapting to these challenges and discuss alternatives for efficient irrigation practices, including advances in irrigation technologies that help growers produce high quality fruit.
In addition to the primary speakers, viewers are invited to share solutions, ask questions, and interact with the specialists and grower panelists. Preregistration is not required to attend. To join, simply go to the Meet-Up Zoom Site. If you can't access, copy and paste the URL in your browser. https://bit.ly/2024-virtual-meetup
Topics
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. If you wish to view growth regulators only, then under the 'Advance Search' for 'Pesticide Type' choose growth regulator. To help you navigate the guide, we have developed a brief tutorial video as well as a how to use guide.
Edited by Michelle Cortens, Tree Fruit Specialist
Perennia Food and Agriculture Corp.
Perennia Food and Agriculture Corp.
