Tech Guide - BASF Serifel - 230607

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Serifel® Biological Fungicide

Technical guide

Break the mould

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Serifel® Biological Fungicide

Breaking the Mould

Serifel® Biofungicide will change the way strawberry and grape growers manage their botrytis programs. Its complementary multiple modes of action provide an alternative to conventional fungicides and will reduce total residues as it controls the disease – including strains with developed resistance – right up to harvest.

As a biological fungicide, Serifel can be used up to ten times each growing season and has no withholding period. Adding it to the rotation makes the total spray program much more flexible, reliable and sustainable.

Applying Serifel right up to picking is an attractive option because the formulation is much more concentrated than other biological fungicides. Achieving control with significantly less active ingredient means that Serifel is much less likely to leave visible spray deposits that could affect the marketability of fresh strawberries and table grapes.

General Characteristics of Bacillus Amyloliquefaciens Strains

• Naturally occurring soil-borne bacteria
• Found all over the world
• Produce extremely stable spores
• Produce a unique combination of metabolites
• Are NOT toxic to human beings

Contents

• Product profile 3
• Use profile 3
• Crops 4
• Mode of action 5
• Factors affecting performance 6
• Resistance management 7
• Compatibility 7
• Spray deposition 7
• Serifel in grapes
  • Trial results 8
  • Application guidelines 9
• Serifel in strawberries
  • Trial results 10
  • Application guidelines 11

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[Image: Close-up of green grapes]

Product Profile

• Active ingredient: Bacillus amyloliquefaciens strain MBI600 (min 5.5 x 10^10 cfu/g)
• Mode of action: Group 44. Microbial disruptors of pathogen cell membranes.
• Formulation: Wettable powder
• Pack size: 2 kg
• Compatibility: Serifel can be tank-mixed with a range of other fungicides and other crop protection products. See page 7.
• Rainfastness: Serifel shows excellent rainfastness.

Use Profile

• Target disease: Botrytis cinerea (Botrytis bunch rot/grey mould)
• Crops: Strawberries, Table grapes, Wine grapes
• Rates:
  • Grapes: 50-75g/100L (dilute spraying)
  • Strawberries: 500 g/ha
• Maximum sprays per growing season: 10
• Spray intervals: 3–14 days
• Withholding period: None

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Modes of Action

Serifel’s active ingredient – Bacillus amyloliquefaciens strain MBI600 – is a beneficial spore-forming, rod-shaped bacterium that colonises the leaf surface of plants.

Serifel works best as a preventative treatment. Application before disease pathogens have established on the plant gives Serifel time to germinate, colonise the plant surface and produce its disease-fighting metabolites.

As a contact biological fungicide, Serifel forms a ‘shield of protection’ against a broad spectrum of plant pathogens, including Botrytis cinerea, thanks to three modes of action:

[Images: Three petri dishes showing: 1. Botrytis applied before Serifel, 2. Serifel and botrytis applied in the same time, 3. Serifel applied before botrytis inoculation]

1. Competition for space: When the Serifel spores are the first to occupy the limited space on the plant, they physically exclude plant pathogens from occupying the same space.
2. Competition for sustenance: Serifel depletes the supply of nutrients available to the pathogen spores on the plant surface.
3. Production of antifungal metabolites: Serifel produces specific metabolites – called iturin and surfactin – that prevent pathogens from germinating by disrupting their cell membranes.

Membrane Disruption

Serifel is a pure spore formulation. It doesn’t contain metabolites, but they are produced by the bacteria that grow on the plant surface after application.

The metabolites produced are iturin and surfactin – lipopetide metabolites that are able to penetrate into membranes and disrupt them.

The Serifel metabolites are similar enough to membrane building blocks to penetrate and disrupt the normal packing.

The altered membrane structure is less stable due to buckling and pore formation. The membranes begin to leach, the cell functionality is disrupted and the cell dies.

[Diagram: Showing a biological membrane with water-soluble and greasy components. Iturin and Surfactin molecules infiltrate the membrane, causing it to be disrupted, leading to cell death.]

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Optimal Conditions Produce Optimal Results

Its unique modes of action mean Serifel needs to be used strategically and as recommended to achieve its full benefit.

When conditions are not ideal, the rates of growth and colonisation will be slowed and control may be reduced.

Agronomists and growers who understand how the factors listed below affect Serifel’s performance will have the most success in creating fully integrated botrytis management programs.

Optimal Environmental Conditions

• Temperature: 25–45° C Serifel is able to grow under a wide range of temperatures (from 15° up to 50° C). At extremes, the rate of bacterial growth (and therefore efficacy) will be lower.
• Leaf surface water: >90% Moisture is needed for spore germination and growth of Serifel.
• pH: 5.4–6.8 Serifel is effective across a broad pH range, but slightly acidic conditions are optimal for rapid growth.

Optimal Application Conditions

• Timing: Pre-infection Serifel needs to be used preventatively so it can occupy space on the plant surface and leave no room for pathogens.
• Water volume: Point of run-off Using sufficient water volumes will help distribute the Serifel spores, but spray run-off should be avoided because it reduces Serifel activity on the leaf.
• Using adjuvants: Spreading or fixing agents with low impact on leaf water In 82% of studies across four pathogen/crop systems, using an adjuvant improved Serifel’s efficacy. Sticking agents may be used to increase retention on the plant surface. Spreading agents can be used to improve surface distribution, but may also result in a thinner water film on the leaf. The subsequent lack of moisture will potentially limit the growth of Serifel.
• Disease pressure: Low Serifel shows the highest efficacy when disease pressure is low.

[Image: Strawberries]

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Toxicity and Environmental Impact

The active ingredient in Serifel is a naturally occurring strain of bacteria. Contact between non-target organisms and Bacillus amyloliquefaciens occurs constantly in nature with no negative effects.

Its low environmental impact and toxicity allows Serifel to be used in sensitive areas and in cropping systems where pollinating bees are present. Serifel can also be used in Integrated Pest Management (IPM) programs where beneficial insects and mites are used for insect control.

Serifel Biofungicide has organic certification.

[Logo: Certified Allowed Input, ACO CERT. NO. 12801]

Spray Deposition

Serifel is one of the most concentrated biological fungicides available anywhere in the world. The high loaded, pure spore formulation allows effective application at lower rates compared to other biological products, normally leaving no detectable spray deposits.

[Images: Comparison of spray deposition on strawberries and grapes between "Biological competitor" and "Serifel"]

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Resistance Management

There is no cross-resistance between Serifel and conventional chemical fungicides. Trials have shown that Serifel can control botrytis with resistance to both QoI and SDHI fungicides. However, a spray program including chemical fungicides to which there is tolerance may involve high disease pressure – making early, preventive application of Serifel even more critical.

[Chart: Control of QoI-resistant botrytis. Shows % disease severity for UTC, Strobilurin 1, Strobilurin 2, and Serifel for both sensitive and resistant strains.]

[Chart: Control of SDHI-resistant botrytis. Shows % disease incidence for UTC, SDHI, and Serifel for both sensitive and resistant strains.]

Compatibility

Serifel is compatible with a range of potential tank-mix partners. These tables are based on the testing of relevant mixing partners at label rates and a dilute water volume per 100L water. Further testing is expected to increase the list of mixing partners.

Testing of further tank-mix partners is ongoing. For information about compatibility with products and active ingredients not listed here, contact your local BASF representative.

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Serifel in Grapes – Trial Data

[Chart: High disease pressure in chardonnay grapes. Shows % of bunches infected with botrytis at various days after treatment (DAT) comparing Untreated control, cyprodinil + fludioxonil, Serifel 50g/100L, and Serifel 75g/100L.]

[Chart: Lower disease pressure in chardonnay grapes. Shows % of bunches infected with botrytis at various days after treatment (DAT) comparing Untreated control, cyprodinil + fludioxonil, Serifel 50g/100L, and Serifel 75g/100L.]

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Serifel in Grapes – Application Guidelines

Serifel has no curative activity, so it must be applied preventatively. Applications should be at least 3 days and up to 14 days apart, but trial work suggests the spray interval should generally be no more than 7 days.

Serifel should only be applied when the temperature is unlikely to drop below 15°C. Applying Serifel with spreader-type adjuvants that improve leaf and cluster coverage can stabilise Serifel’s efficacy. Using greater water volumes for optimal crop coverage will also help ensure reliable performance. Serifel can be tank-mixed with conventional fungicides for application at the key crop stages (BBCH 68, 75, 81) and then used as a standalone spray for the final applications before harvest.

Application rates: 50–75 g/100 L Application timing: Apply preventatively, before disease develops. Key application timings include flowering, pre bunch closure, veraison and pre-harvest.

Suggested use patterns:

[Legend: Grey box = Conventional chemistry (with suggested mode of action group numbers), Light red box = Filan, Dark red box = Serifel]

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Serifel in Strawberries – Trial Data

The first graph below shows how Serifel can be used to complement conventional treatments rather than replace them altogether.

[Chart: Serifel as a complement to conventional treatments. Shows % of berries infected with botrytis at various days after treatment (DAT).]

[Chart: Botrytis control in strawberries. Shows % of berries infected with botrytis at various days after treatment (DAT).]

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Serifel in Strawberries – Application Guidelines

Serifel has no curative activity, so it must be applied preventatively. Applications should be at least 3 days and up to 14 days apart, but trial work suggests the spray interval should generally be no more than 7 days.

Serifel should only be applied when the temperature is unlikely to drop below 15°C. Applying Serifel with spreader-type adjuvants that improve leaf and cluster coverage can stabilise Serifel’s efficacy. Using greater water volumes for optimal crop coverage will also help ensure reliable performance. Serifel can be tank-mixed with conventional fungicides for application under low to medium disease pressure and used as a standalone spray between pickings and during the pre-harvest interval for chemical products.

Application rates: 500 g/ha Application timing: Apply preventatively, before disease develops. Apply again at 3–14 day intervals as required.

Suggested use patterns:

[Legend: Grey box = Conventional chemistry (with suggested mode of action group numbers), Dark red box = Serifel]

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Serifel® Biological Fungicide

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