Using Sweet Orange Oil in Biocontrol

Technical articles

Preparations based on essential oils of orange sweet are an alternative to conventional products in the fight against various diseases caused by fungi and pests of crops^[1]. They are notably used against:

downy mildew of grapevine
lettuce downy mildew
the powdery mildew
alternaria of carrot
scab
soft-bodied insects (Thrips, Whiteflies, Leafhoppers)

How does it work?

Sweet orange essential oil has a very rapid effect on fungi spores, due to its drying capacity, but its action is short-lived. It is therefore recommended to use this product in combination, while reducing the doses of the associated products. Sweet orange essential oil is thus an interesting alternative in a strategy of reducing conventional products and lowering IFT.

Fungicidal action

Products based on sweet orange essential oil act by contact on pests (fungi or insects)^[2]:

They provide a curative and eradicating shock effect, complementary to preventive protection.
They allow to strongly reduce the number of secondary infections by drying sporulations.
They limit the wetting of vegetation, even in case of light rain.
They destroy spores present on leaves.

Products based on sweet orange essential oil, associated or not with copper (50g/ha), provide comparable efficacy to copper alone at 600g/ha in the fight against downy mildew^[3].

Insecticidal and acaricidal actions

Products based on sweet orange essential oils act by contact on soft-bodied insects^[4]:

they degrade the insect cuticle
they dry out the body and wings of the pest
they block respiratory pathways causing the death of the insect

These products are very effective on larvae and adults.

Benefits

No residues (no Maximum Residue Limit, making it interesting in quality approaches such as « residue-free »)
Usable in Organic Farming
No risk of resistance
Not counted in IFT
Short pre-harvest interval allows flexibility of intervention up to the eve of harvest

Application modalities

Volumes

Vine (wine grape): 2 applications at 0.9L/ha – 1.2L/ha (0.6 – 0.8L/hL based on 150L of water) replacing 2 fungicide treatments against powdery mildew, or 6 applications at 0.6L/ha (0.4L/hL based on 150L of water) in combination with fungicide program applications against downy mildew and powdery mildew at reduced dose. Depending on the chosen strategy, the IFT reduction will be 1.5 to 3 per year. In situations of high disease pressure, sweet orange essential oil provides additional protection when using fungicides without modulating their dose and thus without reducing the IFT^[5].
Arboriculture (pome fruits, peach tree, apricot tree, small fruits): 2 applications at 0.4L/hL (2L/ha based on 500L of water) replacing 2 fungicide treatments against powdery mildew, and/or throughout the program (max 6 applications) at 0.2L/hL (1L/ha based on 500L of water) in combination with fungicide applications against powdery mildew at reduced dose.
Market gardening (carrot, strawberry, cucumber, lettuce, melon, tomato): The use of sweet orange essential oil allows saving between 0.5 and 2 IFT per year on a standard protection program against powdery mildew, downy mildew and/or alternaria (depending on crops and approved uses), either replacing conventional solutions or in strategies combined with dose reduction.
Ornamental Plants (Trees and shrubs, Flower crops and green plants, rose): The use of sweet orange essential oil allows saving between 0.5 and 2 IFT per year on a standard protection program against powdery mildew, downy mildew and/or black spot diseases (depending on crops and approved uses), either replacing conventional solutions or in strategies combined with dose reduction.
Tropical crops (mango tree, papaya tree): 2 applications at 0.4L/ replacing 2 fungicide treatments against powdery mildew, and/or throughout the program (max 6 applications) at 0.2L/hL in combination with fungicide applications against powdery mildew at reduced dose.

Products based on sweet orange essential oil are registered on the standardized action sheet No. 2018-044 giving entitlement to CEPP.

Barriers to overcome and success conditions

Sweet orange essential oil can be applied just before a contamination period to reduce the inoculum present in the plot thanks to its action on spores. It can also be positioned at symptom appearance to benefit from its eradicating action. Treatment efficacy is observable within 7 days following application. Repeated applications of low doses will provide better efficacy than a single application at a high dose.

Spraying quality, especially coverage of the entire vegetation with a sufficient volume of water, is crucial to maximize the contact action of the solution.

The impact of sweet orange essential oil on beneficials (predatory mites, parasitoids, predatory bugs, pollinators, lacewings…) has been evaluated by an independent organization according to IOBC standards, and for most of them, the impact is neutral to slightly toxic when used at recommended doses, on an already established population. The volatility of sweet orange essential oil limits persistence on the plant compared to conventional insecticides. Its impact duration is therefore short, and a release of beneficial organisms is possible shortly after application. However, certain recommendations should be followed when using sweet orange essential oil.

Favor releases of beneficials after application.
Apply on already established beneficial populations. Generally, avoid applications during the establishment phase of beneficials, avoid targeting young stages.
Respect maximum product concentration conditions to avoid phytotoxicity risks (burns) on crops (tomato and cucumber are particularly sensitive).

Cost

Between €20 and €40 / ha depending on the solution used (for a maximum dosage of 1.6 L/ha)^[6]

Commercial solutions

Sweet orange essential oils are present in various commercial solutions, find them here.

Sources

↑ Andrivon D., Bardin M., Bertrand C., Brun L., Daire X., Fabre F., Gary C., Montarry J., Nicot P., Reignault P., Tamm L., Savini I., 2017. Can we do without copper in organic crop protection? Summary of the collective scientific expertise report, INRA, 66 p.
↑ Vivagro, Vine: Strengthen your Downy Mildew protection
↑ Réussir Vigne, 2014, Using Prev-Am in combination.
↑ Oro Agri, Prev-AM Plus: how does it work?
↑ Contrat Solutions: https://contratsolutions.fr/le-contrat-de-solutions/utilisation-de-lhuile-essentielle-dorange-pour-le-controle-des-maladies-cryptogamiques-en-viticulture-arboriculture-maraichage-et-sur-plantes-ornementales/
↑ Cost of supplies, Fungicides

Appendices

Est complémentaire des leviers

S'applique aux cultures suivantes

[1] Andrivon D., Bardin M., Bertrand C., Brun L., Daire X., Fabre F., Gary C., Montarry J., Nicot P., Reignault P., Tamm L., Savini I., 2017. Can we do without copper in organic crop protection? Summary of the collective scientific expertise report, INRA, 66 p.

[2] Vivagro, Vine: Strengthen your Downy Mildew protection

[3] Réussir Vigne, 2014, Using Prev-Am in combination.

[4] Oro Agri, Prev-AM Plus: how does it work?

[5] Contrat Solutions: https://contratsolutions.fr/le-contrat-de-solutions/utilisation-de-lhuile-essentielle-dorange-pour-le-controle-des-maladies-cryptogamiques-en-viticulture-arboriculture-maraichage-et-sur-plantes-ornementales/

[6] Cost of supplies, Fungicides

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