Today's newsletter focuses on early season disease management including the season's first apple scab infection event and considerations for fire blight sanitation. We review horticulture practices including notching for blind wood, reminders for planting, and resources on planning windbreaks. Thanks to the ongoing commitment of the Orchard Outlook Committee members.
Table of Contents:
- 2024 Degree Day Accumulations
- Cumulative Precipitation
- Apple Buds
- Pear and Stone Fruit Buds
- Apple - Scab
- Fire Blight Sanitation
- European Red Mite
- Pre-emergence Residual Herbicides
- Post-emergence Herbicides
- Notching for Blind Wood
- Pruning
- Fertilizing
- Liming
- On-farm Nursery
- Land Preparation
- Windbreaks
- Resilient Agriculture Landscape Program
Weather
2024 Degree Day Accumulations
- Approximately 9% more plant development heat units compared to the 5-year average, and 25% more compared to the 10-year average.
- Approximately 26% more plant development heat units compared to 2023, and 2% less compared with 2022.
- Approximately 3% less insect development heat units compared to the 5-year average, and 9% more compared to the 10-year average.
Cumulative Precipitation
Bud Development
Apple Buds
Pear and Stone Fruit Buds
Diseases
Apple – Scab
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.
Recommendations:
- Currently there is no rain in the forecast but do not let it lure you into a false sense of safety because precipitation forecasts can change quickly. There has been more tissue exposed and spores are maturing so orchards should receive regular fungicide protection. According to the forecast, ascospores are expected to mature at a rate of 0.5% per day and within the next five days about 4% ascospores are expected to mature and be available for release.
- 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.
Fire Blight Sanitation
Recommendations:
- Please note that tissue injury could occur when copper is used alone or combined with oil when hard frosts/freezing temperatures occur, such as those temperatures currently forecast for the next few nights.
- A copper application is recommended when buds are at the green tip stage. A fixed copper product such as Copper Spray Fungicide (50% copper oxychloride) is recommended because it is resistant to being washed off by rain. If applied later than green tip, residues that persist on fruitlets can cause russetting which is a concern for fresh fruit varieties. Processing varieties where russet is tolerable can be treated later as well as nonbearing trees.
- 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.
- 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.
Insects
European Red Mite
Weed Management
Recommendations:
- 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.
- 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.
- 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.
Horticulture
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. 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.
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
- 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. Rods may also be put into place early to avoid knocking off buds if done at a later timing.
- Early application of granular fertilizer can minimize the risk of leaf burn. Otherwise, granules can get trapped and sit in new leaf tissue that is close to ground level.
Land Preparation
- Wet conditions are a great opportunity for marking wet spots in the field to repair tile drainage.
- 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. 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.
Windbreaks
- If you are considering installing a windbreak, listen to last year's podcast episode about species composition, design and maintenance tips, "E1 S4. From Windstorms to Windbreaksl Guest Jenny Liu".
- Be careful that your windbreak design does not create issues with snow accumulation in the orchard that could break tree limbs.
- Review the following resources that have been recommended for our region, "Selection and arrangement of plants in shelterbelts and buffer strips" and an interactive website.
- Funding is available from the NSDA program 'Resilient Agricultural Landscape Program.'
Events and Notices
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. For more details, visit the NSDA Program page.Online Pest Management Guide
Perennia Food and Agriculture Corp.