Using Diatomaceous Earth for Grain Storage
Diatoms are unicellular micro-algae enclosed by an external skeleton mainly composed of silica. Fossil deposits of diatom skeletons are called diatomaceous earth. Diatomaceous earth is an active substance authorized in the European Union since 2009. It has no Maximum Residue Limit (MRL). An insecticidal and acaricidal formulation based on diatomaceous earth has a Marketing Authorization (MA). This product, named Silicosec®, is manufactured by a German company and distributed in France by Kreglinger. This formulation in the form of a Contact Powder (CP) containing 920 g/kg of diatomaceous earth is authorized for two uses:
- General treatments: disinsection of premises, structures, and equipment, at a maximum dose of 10 g/m² with a limit of one application per year;
- Treatment of cereals: treatment of harvested products against pests of stored products, at a maximum dose of 2 kg/t with a limit of one application per year.
How does it work?
Due to its composition (silicon dioxide, chemically inert compound), Silicosec® absorbs the fatty bodies of the cuticle of insects and by a complementary abrasive effect, causes the death of insects by desiccation. The higher the grain temperature, the more active the insects and the higher the mortality. The nature of the product might suggest an absence of danger. It is therefore specified that "to protect the operator and the worker if they must intervene in the application area, wearing gloves, work clothing, and respiratory protection (FFP2 mask compliant with EN 149 standard) is necessary. Indeed, although this substance is not classified as toxic, it may nevertheless present an inhalation risk for exposed operators." Finally, the marketing authorization of Silicosec® comes with a single usage constraint: the prohibition of pneumatic transport of grains after treatment.
All species of pests of stored products do not have the same sensitivity to diatomaceous earth. Insects have been ranked from most to least sensitive during treatment on the total grain mass: the flat grain beetle > the grain beetle > the weevils > the rice weevil > the triboliums.
In the trials conducted, the efficacy is comparable to the reference treatment Pirigrain (Pirimiphos Methyl) at a temperature of 25°C, as observed in the weeks following harvest. It was noted that a temperature drop of 10°C results in an average efficacy loss of 60% on rice weevils. The contact duration of insects with the product must be 14 days to approach 100% mortality.
Benefits
- Thorough cleaning of premises with an application at a dose of 10 g/m² one to two months before grain reception
- Possibility to intervene as a catch-up treatment on the grain
- Efficacy enhanced by warm temperatures and dry grain
Limitations
- Respiratory protection for the applicator is mandatory and consideration of constraints related to grain transport
- Lower efficacy on tribolium
- Application on grain causes significant specific weight losses (from 3 to 5 kg)
Advisor's opinion
Diatomaceous earth is one of the available solutions to combat insects in storage. It is now available in France with the formulation Silicosec®. Except for exceptional treatment of an entire batch at a high dose, diatomaceous earth is not suitable for curative treatment. It is more of a tool for preventive protection against infestations. It is an effective lever under certain conditions of use (high temperatures and low humidity), which should not be used alone but in combination with other measures such as prior cleaning for premises treatment.
Cost
7.5 to 10 €/kg
Sources
- This article was written based on the document The fields of possibility in biological control on large crops jointly authored by François DUMOULIN, Hélène BAUDET, Gilles SALITOT, and Inma TINOCO from the Chamber of Agriculture of Oise.
Appendices
Est complémentaire des leviers
- Practicing biocontrol using natural substances
- Practicing biocontrol=== S'applique aux cultures suivantes ===
- Cereals=== Défavorise les bioagresseurs suivants ===
