By Grace Kim

Swedish researchers advance RNA spray method for crop protection

Swedish University of Agricultural Sciences (SLU) plant pathologists have published fresh findings on spray-induced gene silencing (SIGS), an RNA-based crop protection method designed to replace broad-spectrum chemistry in cereals, potatoes, and oilseeds.

SLU's research communications channel framed the work as a contribution to Europe's pesticide-reduction drive under Farm to Fork targets, which aim to cut chemical pesticide use and risk 50% by 2030. The technology is sequence-defined and target-specific by design.

How does SIGS work?

A laboratory-synthesized double-stranded RNA strand is applied to plant surfaces. The strand matches a single gene inside a feeding pest or fungal cell. It binds to that gene's messenger RNA. The cell can no longer build the matching protein. The pest dies or the pathogen stops. Pollinators and beneficial predators are not affected.

Spray residues degrade in the field within days. No chemical load reaches grain, milk, or water tables. Production cost at scale runs a few cents per microgram, with per-hectare application rates expected to track conventional contact chemistry once commercial formulations arrive.

What is the regulatory picture?

The U.S. EPA registered the first RNAi-based corn rootworm trait inside a Bt stack in 2017. No stand-alone SIGS spray has full U.S. or EU registration today. EFSA has issued scientific opinions on dsRNA-based pesticides, but the EU has not completed a regulatory pathway specific to topical RNA sprays. A draft Commission proposal on new genomic techniques could fold certain SIGS uses into a lighter notification regime if adopted.

That timing matters. Standard active-substance review in the EU typically runs 24 to 36 months from dossier submission. A low-risk-substance route under Regulation 1107/2009 can clear in roughly half that time. The cost gap between the two routes can exceed €2 million in dossier preparation, a meaningful difference for start-ups.

Who is positioning for the shelf?

Bayer's BioDirect platform, Syngenta's collaboration with Ginkgo Bioworks, and U.S. start-ups including GreenLight Biosciences and AgroSpheres have built IP around RNA design and manufacture. Active programs cover Colorado potato beetle, varroa mite, and diamondback moth. Horticulture and specialty crops are likely first to commercialize, where per-hectare treatment value is highest.

For input makers, cooperatives, and farm-supply retailers, the implication is inventory planning, not sales force expansion. SIGS candidates are likely to ship in 250-milliliter to 500-milliliter bottles, refrigerated for shelf life, and may require cold-chain distribution that not every ag-input dealer can support.

The bottom line

SLU's progress adds peer-reviewed weight to a field that has produced more published papers than registered sprays. Commercial scale-up at commodity price points, not greenhouse efficacy, is the binding constraint going forward. Distributors who warehouse SIGS inventory in 2026 will hold channel position when the first EU approvals land.