1. Presentation

Characterization of the technique

Description of the technique:

Why sugar in agriculture?

Sucrose is present in all plants containing chlorophyll; it is a natural product of photosynthesis. We speak of soluble sugars because they are dissolved in water. These sugars are therefore present on the surface of plants, more or less depending on the time of day, leaf age, plant physiology, and plant species. These sugars are responsible for important signals in the plant and in pests, which is why they interest us. They also play a role in integrating internal and external elements to maintain nutritional characteristics for the plant. They are involved in managing hormonal growth and development processes of the plant as well as responses to biotic and abiotic stresses. Some genes are regulated by sugar.

What objectives and interests?

Find alternatives to phytosanitary products in view of the Eco-phyto law
Reduce environmental impacts of certain inputs in agriculture
Find viable solutions that integrate easily into technical itineraries

What are the advantages of using sugar?

Acts in just a few hours and lasts for several days
Not persistent nor toxic in the environment or on plants
Natural molecules, inexpensive and reproducible
Wide range of uses: Pests (Fungi; insects; "nematodes") and crops (Perennials; annuals; monocotyledons; dicotyledons; varietal resistances)
Systemic: Non-sprayed parts are also protected (Epigeal and hypogeal)
Possibility to combine with phytosanitary products by reducing dose but increasing efficacy
Positive effects on the plant (stem growth, roots, and yields) but confirmations are still needed.
Easy integration into technical itineraries

Example of implementation:

Maize

European corn borer: Foliar application at the 4 to 5 leaf stage (10 ppm sucrose), it must be done before the attack (preventive) and egg-laying of the borer so the plant has time to prepare its defenses since sugar creates a signal. The intervention affects egg-laying even 20 days after application. Positive effects on stem and root growth are observed. Several effects are noted depending on the different sugars.

Rootworm: Application of 10 ppm sucrose or fructose => reduction of root damage comparable to FORCE 1.5G

Calculation of ppm: 10 ppm = 1g/100 l

Details on the technique:

The technique itself

When sprayed in underdose, soluble sugars can penetrate a plant, thus they travel between the plant surface and its tissues via the cuticular pathway. The insect uses soluble sugars as a plant recognition signal. Sugars prepare the plant to defend itself against different stresses at different times; a soluble sugar spray in underdose thus modifies the plant/insect relationship. They are said to intervene in the signaling pathway of attacks. Sugar signaling pathways are complex phenomena, still little known and unexplained today, but this spraying, early in the morning (8 to 9 solar hours), causes a biochemical stimulus in the plant or a signal that induces antixenosis¹; moreover, it is a systemic resistance induction reaction² because sugars penetrate the plant. It is a preventive and partial action.

Why apply early in the morning?

Between 8 and 9 am is when the leaf contains the least sugar, so the penetration rate will be highest. This can be seen on the graph. Application must also be rigorous; the spray mixture must be applied shortly after preparation.

Implementation period On established crops

Partial action and low persistence over time, applications must be renewed if disease and/or pest pressures persist

Spatial scale of implementation Plot

Application of the technique to...

All crops: Not generalizable

Not all pests are sensitive to sugar underdoses.

Moreover, for the same crop, some varieties do not respond to sugar addition (e.g., for apple Jonagold).

All soil types: Easily generalizable

A priori, technique independent of soil type.

All climatic contexts: Easily generalizable

A priori, technique independent of climate type.

However, it is necessary to respect:

sugar application period => rather early in the morning when sugar quantity on leaf surfaces is low
"quick" application after spray mixture preparation

Regulation

Approval of Fructose and sucrose as basic substances (August 2014, 2015)

2. Services provided by the technique

3. Effects on the sustainability of the cropping system

"Environmental" criteria

Effect on air quality: Increasing

acidification: NEUTRAL

phytosanitary emissions: DECREASE

GHG emissions: NEUTRAL

particulate emissions: DECREASE

Effect on water quality: Increasing

pesticides: DECREASE

turbidity: NEUTRAL

Effect on fossil resource consumption: Decreasing

fossil energy consumption: DECREASE

phosphorus consumption: DECREASE

Other: No effect (neutral)

"Agronomic" criteria

Productivity: No effect (neutral)

Some favorable effects on yield depending on species and varieties grown

Production quality: Increasing

Less pesticide residues at harvest especially on late applications (e.g., regulation of bruchid on faba bean at "young pod" stage)

Soil fertility: Increasing

No destruction of auxiliary by fungicide or insecticide use => increase in biological soil fertility (no impact on chemical and physical soil fertility)

Water stress: No effect (neutral)

Functional Biodiversity: Increasing

No destruction of auxiliaries by fungicide or insecticide use

"Economic" criteria

Operating costs: Decreasing

Sugar is cheaper than phytosanitary products, but this technique retains mechanical intervention (sprayer).

Mechanization costs: No effect (neutral)

May increase if multiple passes are necessary.

Margin: No effect (neutral)

"Social" criteria

Working time: No effect (neutral)

Neutral to increase if interventions are renewed

Peak period: No effect (neutral)

Effect on farmer health: Increasing

Reduced exposure to phytosanitary products

Observation time: No effect (neutral)

4. Favored or disadvantaged organisms

Favored pests

Organism	Impact of the technique	Type	Details

Disadvantaged pests

Organism	Impact of the technique	Type	Details
Codling moth (Cydia pomonella)	LOW	pest, predator or parasite
Lobesia botrana	LOW	pest, predator or parasite	Lobesia botrana of the vine test: sugar + copper
bruchid beetle of faba bean	LOW	pest, predator or parasite	To be confirmed!
western corn rootworm	LOW	pest, predator or parasite
downy mildew	LOW	pathogen (pest)	Downy mildew of clusters test: sugar + copper
European corn borer	LOW	pest, predator or parasite
European corn borer	LOW	pest, predator or parasite	European corn borer on melon To be confirmed!

Favored Auxiliaries

Organism	Impact of the technique	Type	Details

Disadvantaged Auxiliaries

Organism	Impact of the technique	Type	Details

Favored climatic and physiological accidents

Organism	Impact of the technique	Details

Disadvantaged climatic and physiological accidents

Organism	Impact of the technique	Details

5. For more information

SWEET: Biocontrol project by micro-doses of sugar
-ITAB, Website
Use of micro-doses of sugars in plant protection
-Arnault I., Bardin M., Ondet S., Furet A., Chovelon M., Kasprick A.-C., Marchand P., Clerc H., Davy M., Roy G., Romet L., Auger J., Mançois A., Derridj S.

Innovations Agronomiques, Peer-reviewed journal article, 2015

Soluble sugars, an opportunity for sustainable agriculture?
-Derridj S., Arnault I., Nicholas A., Birch E., Elad Y., Lombarkia N., Couzi P., Pierre P., Auger J.

Phytoma, Peer-reviewed journal article, 2011

Use of Sugars in Crop Productions
-Sabourin T. Minette S.

CRA Nouvelle Aquitaine, Technical brochure, 2017

Fructose: Substance usage sheet
-Deniau M.

ITAB, Technical brochure, 2019

Sucrose: Substance usage sheet
-Deniau M.