Eastern Filbert Blight Spray Schedule (Month-by-Month Calendar)¶
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Managing Eastern Filbert Blight (EFB) requires a disciplined approach, as the disease kills trees slowly and fungicide benefits may not be visible for 3 to 6 years. This eastern filbert blight spray schedule calendar provides the critical timing and application strategies growers need to protect new growth and ensure long-term orchard health.
When EFB Infection Happens (Spray Timing Basics)¶
Effective control of Eastern Filbert Blight hinges on understanding its latent period and infection window. The primary goal of chemical control is to protect all new growth from infection, which makes thorough coverage of branches essential. Because the disease has a significant latent period, the full impact of your fungicide applications will only become evident several years after treatment begins.
The most critical window for application starts at budswell and continues through budbreak. Applications should begin at these early phenological stages and continue at two-week intervals until early May. This timing ensures that protective layers are present on the tissue when spores are most likely to land and infect. Missing this early window significantly reduces the efficacy of the program, as later applications cannot reverse infections that have already established themselves in the wood.
Month-by-Month Fungicide Spray Calendar¶
Creating a precise calendar is vital because EFB management is not a one-time event but a seasonal commitment. Below is a month-by-month breakdown based on standard temperate hazelnut growing regions.
January–February: Dormant Season Preparation During the dormant season (Stages 1-2), no fungicide sprays are typically applied for EFB. Instead, this period is dedicated to scouting. Growers must identify and remove all infected wood. This physical removal reduces the inoculum load for the upcoming season. It is crucial to destroy this material properly to prevent spore dispersal.
March: Budswell to Budbreak This is the start of the active spray window. As buds swell and break, the first application should be made. The objective is to cover all emerging shoots. Since orchards can be dense and tall, achieving good coverage is challenging even with high-quality air-blast sprayers. Ensure your equipment is calibrated to penetrate the canopy effectively.
April: Early Shoot Elongation By April, shoots are elongating, and the first leaves are fully open. This is typically the second application window, occurring roughly two weeks after the March spray. Consistency in timing is key; aim for 10 to 14-day intervals between sprays if using protectant fungicides like copper-based products.
May: Final Protective Spray Continue the two-week interval schedule until early May. This usually constitutes the third or fourth application of the season, depending on the exact timing of budbreak. After early May, the risk of new infections that can be controlled by sprays diminishes significantly for the current season’s growth cycle.
June–July: Monitoring and Pruning No fungicide sprays are recommended for EFB during June and July. Instead, focus shifts to scouting. New cankers may develop during this time, but fungicides applied in late summer have no efficacy against these new infections. Use this time to mark infected branches for removal.
August–September: Post-Harvest and Dormancy Prep In late August and September, no EFB-specific fungicides are applied. However, this is a critical time for managing other diseases like bacterial blight, particularly in young orchards (less than 10 years old). Copper applications may be used post-harvest and before fall rains for bacterial blight control, but these do not target EFB. Continue scouting for new cankers that must be removed before the next budbreak.
Contact vs Systemic Fungicide Rotation¶
Choosing the right fungicide mode of action is as important as timing. Effective products include various forms of copper, chlorothalonil, fenarimol, and propiconazole. However, not all products are registered in every region, so growers must verify local regulations and consult resources like the PNW Plant Disease Control Handbook.
Contact Fungicides (Protectants) Copper-based products, such as copper octanoate or copper oxychloride, act as protectants. They remain on the surface of the plant tissue and prevent spores from germinating. These are non-systemic, meaning they do not move within the plant. They often have curative properties if applied very early, but their primary role is prevention. A major limitation is that they typically allow only three applications per season to avoid phytotoxicity and resistance issues.
Systemic Fungicides Systemic fungicides, such as those containing propiconazole or fenarimol, are absorbed by the plant and can provide longer-lasting protection. They are effective against established infections if applied early enough. However, relying solely on systemic fungicides can lead to rapid resistance development. Therefore, they should be used in rotation with contact fungicides.
Rotation Strategy To maximize efficacy, rotate between different chemical groups. For example, alternate a copper-based spray with a systemic application. This approach disrupts the pathogen’s ability to adapt. Always check the label for specific reentry intervals and preharvest intervals (PHI). For instance, some copper products require a 24-hour reentry interval, while others may require 48 hours.
Resistance Management Table¶
Resistance management is critical for the longevity of your fungicide program. Overusing a single mode of action can render products ineffective. Below is a general guide to managing resistance based on common fungicide groups used for EFB.
| Fungicide Group | Example Active Ingredients | Mode of Action | Max Applications/Season | Resistance Risk | Management Tip |
|---|---|---|---|---|---|
| M (Multi-site) | Copper (octanoate, oxychloride) | Protectant / Non-systemic | 3 | Low | Use as a backbone of the program; rotate with site-specific fungicides. |
| 3 (DMI) | Propiconazole, Fenarimol | Systemic | Varies by label | High | Limit to 1-2 applications per season; always mix or rotate with a protectant. |
| 4 (SDHI) | Various (check local labels) | Systemic | Varies by label | High | Do not exceed label limits; ensure thorough coverage to reduce selection pressure. |
Note: Always refer to Health Canada’s Pest Management Regulatory Agency website or local extension services for the most current label information and registration status. Do not exceed the maximum number of applications specified on the product label.
Pruning Out Cankers Alongside Sprays¶
Chemical control alone is insufficient for managing Eastern Filbert Blight. Physical removal of infected tissue is a cornerstone of an integrated management strategy. New cankers develop throughout the growing season, particularly in late summer. These cankers serve as sources of inoculum for the following year.
Growers must scout orchards regularly to identify infected wood. All infected branches should be removed and destroyed prior to budbreak in the next growing season. This timing is crucial because removing cankers after budbreak allows spores to be released during the critical infection window. Destruction methods should include burning or deep burial to ensure spores are not dispersed by wind or machinery.
Pruning should be done carefully to avoid damaging healthy tissue. Cuts should be made well below the visible canker, as the fungus can extend further into the wood than the symptoms suggest. Seal large pruning wounds if recommended by local guidelines to prevent secondary infections.
Adjusting the Schedule by Climate and Variety¶
The standard spray schedule assumes a typical temperate climate. However, growers in regions with extended wet springs or delayed budbreak may need to adjust their timing. If budbreak is delayed, the first application should also be delayed to coincide with the actual emergence of new growth. Applying fungicides too early, before budswell, wastes product and provides no benefit.
Variety susceptibility also plays a role. Some hazelnut varieties are highly susceptible to EFB, while others may have partial resistance. Highly susceptible varieties require strict adherence to the spray schedule and thorough coverage. In dense orchards, achieving coverage is more challenging, so growers may need to increase spray volume or use adjuvants to improve penetration.
Finally, consider the age of the orchard. Young orchards (less than 10 years old) may require additional attention to bacterial blight, which can be managed with copper sprays post-harvest. However, for EFB, the focus remains on the spring window. Always monitor local weather conditions; heavy rains can wash off protectant fungicides, necessitating reapplication within the safe interval limits. By combining precise timing, proper fungicide rotation, and diligent pruning, growers can effectively manage Eastern Filbert Blight and protect their hazelnut investments for years to come.