Table of Contents:
- 2021 Degree Day Accumulations
- Soil Temperature
- UPDATE on Weather Stations in the Valley
- Apple - Scab
- Apple - Fire Blight Prevention
- European Red Mite
This year's growing degree day accumulations continue to lead over the 5- and 10-year averages.
Figure 1: Heating degree day accumulations for plant (above 5°C) and insect (above 10°C) development from March 1st to April 26th for the past 17 seasons. Provided by Jeff Franklin (AAFC).
- Approximately 77% more plant development heat units compared to the 5-year average, and 63% more compared to the 10-year average.
- Approximately 161% more plant development heat units compared to 2020, and 39% more compared with 2019.
- Approximately 108% more insect development heat units compared to the 5-year average, and 75% more compared to the 10-year average.
Soil Temperature
The soil temperature maintains its lead over previous years and is certainly ahead of last year's cool temperatures. A temperature of at least 10°C is recommended for soil fumigation with PicPlus. Although the temperature at the 35 cm depth has not yet reached 10°C it is currently on track to reach that point in the near future. Air temperatures will continue to cycle but overall average temperatures will contribute to the rise in soil temperature. Moisture and soil tilth also play a role in fumigation so fumigation will begin when soil conditions are appropriate.
Figure 2: Soil temperatures at 35 cm depth at the Kentville Research Station from 2016 to 2021. Provided by Jeff Franklin (AAFC).
UPDATE on Weather Stations in the Valley
Two more stations are live!
By now you're well aware that the Nova Scotia Fruit Growers’ Association through federal and provincial funding with the Nova Scotia Department of Agriculture has embarked on a smart farm demonstration project to install and maintain weather stations.
Seven of the ten weather stations are now operational. Both Melvern Square and Woodville stations were installed on April 24th. Other operational stations include: Atlanta, Aylesford, Grafton, Mochelle, and Morristown.
Information session - Recording now available
Last Thursday we got together virtually for an information session on weather stations and tools. Candy described the project, Jonathan Bent (Perennia) introduced the technical components of the weather stations, and Michelle Cortens (Perennia) shared advisory information about accessing the data, Maryblyt alerts, and a smart tools project that's under development.The recorded presentation is 35 minutes in length and it's now available to watch on YouTube or in the embedded video below. If you would like to jump to sections of interest, follow the link to YouTube and in the video description you'll find timestamps for topics throughout the video.
Accessing the weather data
There are four locations where anyone can access the live weather data. Choose the formats that work best for you:
- Davis WeatherLink for desktop computer (NSFGA or free account required)
- Davis WeatherLink application for smartphones (NSFGA or free account required)
- NS Tree Fruit Blog
- Cape Breton Mesonet
Historical weather data is a feature of a paid account so NSFGA members and their advisors have access. On April 22nd, Candy sent the login information to members. If you’re not a member, you can access the live/current weather data by creating your own free account on Davis WeatherLink. Search for weather stations and add them to your account.
Bud Development
Buds have continued to grow relatively slowly over the last week. An early region on Middle Dyke Road in the Kentville area is monitored to guide this newsletter. On April 26th, the Idared buds were at the stage of late half-inch green with McIntosh close behind at half-inch green. Honeycrisp was at half-inch green. Ambrosia were at quarter-inch green.
Figure 3: Bud development in an early region on Middle Dyke Road in Kentville on April 26th. Shown from left to right: Idared, Honeycrisp, Ambrosia.
Orchard Outlook committee members reported that apple trees in later regions are generally around green tip to quarter-inch green.
At the Kentville Research and Development Centre, sweet cherries are showing late swollen bud and nearing bud burst. Pear is at late swollen bud.
Diseases
Apple – Scab
Table 1: Apple scab infection events at the Kentville Research Station from April 21st to April 27th, based on the Modified Mills Table.
** 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.
This Orchard Outlook has been published with the input of the Orchard Outlook Committee
Edited by Michelle Cortens, Tree Fruit Specialist
Recommendations:
- A period of rainfall is currently forecast for Thursday, April 29th. With the currently forecast temperatures being a high of +12°C and a low of +3°C, it would take around 16 hours of leaf wetness for an apple scab infection event to occur, according to the Modified Mills Table.
- 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 upcoming product discontinuations.
- 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.
Special notes on products containing Captan:
- The product formulations Maestro 80 DF and Supra Captan 80 WDG are being phased-out. The last date of use is May 10, 2021 and it is fast approaching. The PMRA identified issues with the dry flowables in terms of applicator exposure when mixing and loading. Studies show that water soluble packaging (WSP) reduces handler exposure so it’s an acceptable risk mitigation measure. There are new registrations for the formulations Supra Captan 80 WSP and Maestro 80 WSP.
- Water soluble packaging has been used in the past but now we are looking at more frequent use. Consider these best practices:
- Make sure packets fully dissolve and disperse before adding other products. Packets dissolve faster in warm water than cold water, like dishwasher pods.
- Check the filter after the first use and every couple of uses.
- Be careful mixing. Do not use WSP in a tank mix with boron and rinse the tank well before and after boron.
- If you plan to use oil for European Red Mite control, Captan should be avoided within 7-14 days of an oil application.
- Note that the new captan containing product Maestro 80 WSP has re-entry periods that differ depending on the orchard density and activity (anywhere from 2-24 days).
Apple – Fire Blight Prevention
The goal of copper application is to cover the bark with copper to reduce the population of bacteria on plant surfaces that arise from bacterial ooze around the pink stage. The copper treatment will reduce the initial inoculum and limit the spread of fire blight bacteria to blossoms or wounded tissue on the tree. This strategy is most effective in blocks that had fire blight cankers in the previous two seasons.Recommendations:
- If limited by time, prioritize high risk blocks.
- A copper application is recommended when buds have reached green tip. 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. If applied later than green tip, residues that persist on fruitlets can cause russetting.
- 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.
Insects
European Red Mite
To be most effective, oil application for ERM should be targeted closer to egg hatch – around tight cluster and before pink. Avoid oil if freezing temperatures will occur within 48 hrs. For varieties with Delicious parentage, early applications of oil prior to tight cluster are less likely to result in bark blistering.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.Recommendations:
Residual Herbicides
- Spring is an ideal time for using residual weed control products and they offer a much longer weed control period than post-emergent products such as Ignite and Glyphosate.
- Note the differences in the application directions for the residual herbicides Chateau and Alion.
- Chateau can be applied to young trees (note specific label directions). 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 (note specific label directions).
- 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.
- Note that residual herbicides can damage single tree replacements.
- If weeds are already present, consider adding a post-emerge to a residual herbicide to achieve control.
Post-emerge Herbicides
- Take time to allow concentrated products like Roundup to mix into the solution before adding other products.
- Be careful with tank mixing herbicides. At the Orchard Outlook committee, there was a report that the mixture of Roundup Transorb and 2,4-D Amine herbicide can form a white precipitate. New formulations may behave unexpectedly. If in doubt, consider performing a jar test to test compatibility. The jar test is described in a post by Sprayers 101.
Horticulture
Pruning
- If pruning is delayed, plan a strategy to get the most value for your time. Prioritize young blocks and high value varieties and return to low value areas. This strategy is especially important considering the new captan limitations.
- 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.
- Bearing blocks can be pruned later and are best when pruned prior to bloom.
Fertilizing
- Bud break to bloom is the ideal time for granular fertilizer application to maximize tree growth.
Liming
- 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.
Planting & Nursery Trees
- Remember to document the quality of your 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.
Figure 4: Document the quality of your nursery trees with pictures and notes. Shown from left to right: 1) Trunk damage and canker; 2) bulbous growths known as crown gall; 3) a group of trees with roots washed to document quality even if no issues are apparent.
- If fumigating in the spring, observe the warnings on the label prior to planting to avoid crop injury. Leave the soil undisturbed for 10 to 14 days or longer in wet weather. To verify plant safety, follow the safety germination test described on the label for PicPlus.
- 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.
Pest Management Guides 2021
The pest management guides are available online for download. All changes new to 2021 are made in red text. The information on all expected changes was summarized in a blog post on April 9th.
- Download the 2021 Pome Fruit Schedule
- Download the 2021 Organic Apple Schedule
- Download the 2021 Stone Fruit Schedule
- Download the 2021 Thinners and Growth Regulators Schedule
- Download the 2021 Tree Fruit Weed Management Guide
Events and Notices
For upcoming events, visit the ‘Events’ tab on the NS Tree Fruit Blog. Specific events will be described here when available.
This Orchard Outlook has been published with the input of the Orchard Outlook Committee
Edited by Michelle Cortens, Tree Fruit Specialist
Perennia Food and Agriculture Inc.
