Seed health 2.0: An analysis of portable DNA testing for PVY, PLRV, and blackleg that lets growers triage seed lots the same day

By Lukie Pieterse, Potato News Today

On-farm PCR and CRISPR tools that compress diagnostics to minutes, align with certification, and sharpen virus and wilt control before the first cut

Why on-farm DNA diagnostics now

For seed potato growers, the window between receiving lots and planting is unforgiving. Traditional lab workflows for virus and blackleg testing can take days to weeks, during which risky seed may already be cut, treated, and staged. A new class of portable DNA tools – built around isothermal amplification, handheld qPCR, and, increasingly, CRISPR-based detection – is shifting that timeline to same-day answers.

The core promise is practical: screen more tubers, sooner; rogue or reject with confidence; and reduce the viral pressure and soft-rot risk that compound through the season. This is not a replacement for accredited laboratory testing. It is a front-end triage layer that helps growers make faster, cleaner decisions before planters roll.

Targets: PVY/PVA/PLRV panels, Dickeya/Pectobacterium, and blackleg risk indicators

The surveillance priorities are clear. For viruses, growers need rapid calls on Potato virus Y (PVY) – including necrotic strains – Potato virus A (PVA), and Potato leafroll virus (PLRV). These pathogens are well characterized, with robust primers and probes available, and they strongly influence certification outcomes, stand vigor, and tuber quality.

For bacterial wilt and blackleg, the targets are Dickeya spp. (notably D. solani and D. dianthicola) and Pectobacterium spp. (e.g., P. atrosepticum, P. parmentieri). Field experience and research both point to the same operational need: identify contaminated lots and hotspots prior to cutting and planting, then pair those results with sanitation and handling discipline to prevent spread.

Where available, assays that flag general soft-rot risk factors – such as total Dickeya/Pectobacterium loads in wash water, stems, or lenticels – can help set action levels for rejection or stricter hygiene.

Critically, PVY/PLRV infections and blackleg risk do not distribute evenly within a lot. Rapid, higher-throughput spot checks across pallets or totes, combined with statistically thoughtful sampling, give growers a more faithful map of where risk concentrates. That map drives better decisions: targeted rogueing when prevalence is low, or full lot rejection when prevalence crosses predetermined thresholds.

Workflows: crude prep, isothermal amplification, and sealed-tube readouts on farm

What makes these platforms farm-friendly is the combination of simple sample prep and closed-tube chemistry. In practice, the workflow looks like this:

Sampling. Pull representative sprouts, heel ends, or stem pieces using a clean blade, rotating across bags or bins to avoid cluster bias. For bacterial targets, sterile swabs from stems or cut surfaces often suffice.
Crude extraction. Many modern kits use buffer-based lysis or magnetic beads that take 5–10 minutes without a benchtop centrifuge. For RNA viruses, the extraction step preserves RNA integrity without a full lab workflow.
Amplification. Isothermal methods (LAMP and RPA) run at a constant temperature on compact instruments, avoiding thermal cycling. Handheld qPCR devices now operate from battery packs and smartphone interfaces. Total run times commonly fall in the 20–45 minute range.
Detection. Fluorescence readouts (in-tube) or lateral-flow strips (post-amplification) deliver a binary call, with some platforms providing real-time curves and quantification cycles (Cq) to support semi-quantitative interpretation.
Containment. Sealed-tube or no-open-lid workflows are preferred to prevent amplicon contamination. Where lateral-flow strips are used, strict one-direction handling and bleach cleanup protocols are essential.

Isothermal assays are increasingly favored for field use because they tolerate crude extracts and temperature variation. qPCR remains the reference standard when quantitation and strain discrimination matter most. A sensible hybrid emerges on farm: screen with isothermal amplification for speed and breadth; confirm critical calls (especially lot rejections or regulatory implications) with lab qPCR.

Decision thresholds: setting cutoffs for rogueing or lot rejection

The utility of rapid testing lives and dies with pre-agreed thresholds. Without them, results invite second-guessing in the rush of spring. Practical programs codify thresholds in three tiers:

Clean proceed. No positives detected in a statistically defined sample (e.g., 0/60 tuber sprouts for PVY using a validated kit; 0/30 stem swabs for blackleg bacteria). Proceed with planting under standard sanitation.
Rogue and contain. Low but non-zero prevalence (for example, 1–3 positives in 60 PVY tests) triggers targeted rogueing, stricter knife and belt sanitation, and possibly segregated planting to limit mosaic hot spots and aphid exposure. For blackleg, any positives in a small sample may justify enhanced hygiene only if the sample size is small and the lot is otherwise high value – but that policy should be explicit.
Reject / divert. Positives above a defined prevalence (e.g., ≥5% PVY in a representative sample; repeated Dickeya positives across multiple subsamples) trigger lot rejection for seed use or diversion to non-seed channels, subject to regulations and buyer agreements.

Cutoffs should be tuned to local disease pressure, seed class, and buyer expectations. Importantly, thresholds for PVY and PLRV should account for strain context and downstream vector pressure. A low PVY prevalence planted into a high-aphid landscape can still escalate; planting clean into low vector pressure buys margin.

For blackleg, environmental and handling conditions (cold, wet cutting; delayed suberization; poor box hygiene) modulate the tipping point from latent presence to symptomatic breakdown. Thresholds must be coupled to handling standards, not applied in isolation.

Certification fit: complementing – not replacing – accredited lab tests

Seed certification systems in North America and Europe rest on accredited labs, validated methods, and documented chain-of-custody. On-farm tests cannot – and should not – claim to replace that backbone. Their best fit is pre-certification triage and in-season management:

Pre-plant screening. Quickly screen incoming lots to direct sampling for official tests, identify suspect pallets, and make early rogue/reject calls when time is tight.
Cutting and storage checks. Spot-check for blackleg bacteria around cutting lines, water tanks, and storage intakes. Use results to justify intensified sanitation or to isolate suspect bins.
In-season scouting. Where regulations allow, test symptomatic leaves for PVY or PLRV to decide whether field rogueing is likely to make a difference, and to refine vector control intensity.

Certification agencies increasingly accept field screening as complementary evidence while requiring lab confirmation for official status. Growers benefit when they treat on-farm results as a decision support tool that triggers either immediate action or formal submission to the lab, depending on the threshold crossed.

Resistance stewardship: tuning control based on rapid results

Rapid diagnostics pay off only if they change actions. Two levers matter most:

Virus management. If pre-plant PVY screening suggests non-zero prevalence, step up early aphid monitoring, tighten the timing of mineral oil or alternative anti-feeding strategies where used, and consider earlier vine-kill in high-risk fields to limit secondary spread. In regions with PVY strain variability, prioritize varieties with partial resistance or tolerance where seed is not perfectly clean. Adjust spatial layout to avoid downwind exposure to high-risk blocks.
Blackleg/soft rot sanitation. A single on-farm Dickeya/Pectobacterium positive is a red flag for hygiene. Respond with knife sanitation after every box or defined tuber count, replace or disinfect cutting tables and conveyors more frequently, flush and chlorinate recirculated water per label, and enforce dry, warm suberization windows post-cutting before planting. Segregate suspect seed to the last planted fields to limit cross-contamination.

Stewardship also includes record-keeping. Track test results against actions taken and harvest outcomes. Over a couple of seasons, those data will sharpen thresholds and reveal which interventions actually bent loss curves in your operation.

What’s real today: technologies that already work on farm

Field-ready options now span lateral-flow immunoassays, isothermal DNA/RNA amplification kits, and portable qPCR. Each class has a role.

Lateral-flow immunoassays. Fast, simple strips for PVY and PLRV remain the quickest front-end screen. They detect viral proteins, not nucleic acids, and typically trade sensitivity for speed and ease. They are cost-effective for broad triage, especially from sprout sap in late dormancy.
Isothermal amplification (LAMP, RPA). These methods run at fixed temperatures, tolerate crude extracts, and finish in under an hour. Many kits now integrate fluorescent detection in sealed tubes, reducing contamination risk. For Dickeya and Pectobacterium, LAMP assays have been demonstrated for field use; commercial availability varies by region, but the chemistry is mature.
Portable qPCR. Handheld or small-footprint thermocyclers with battery power and smartphone interfaces bring lab-grade sensitivity closer to the field. While they demand more rigorous extraction and handling, they deliver confirmatory confidence and, in some cases, multiplexing across virus panels (e.g., PLRV/PVY duplex).

For a practical on-farm program, a two-step stack works: screen broadly with immunostrips or isothermal assays, then confirm positives – especially those driving rejection decisions – with portable qPCR or an accredited lab.

Emerging CRISPR diagnostics: what’s promising and what to watch

CRISPR-Cas12/13 detection systems combine an initial amplification step (often isothermal) with a sequence-specific cleavage event that yields a fluorescent or lateral-flow signal. For plant viruses, recent studies show high sensitivity and excellent strain specificity, with the potential for low-cost, disposable cartridges. The engineering trajectory points toward cartridge-based CRISPR panels that could, in time, cover PVY strain groups and PLRV in a single run, with visual readouts and no open-tube steps.

Where does this stand today? Pilot assays exist in academic and applied research settings; several diagnostics companies active in human health CRISPR testing are exploring agricultural use cases. Expect early commercial kits for common plant viruses to reach the market as manufacturing and regulatory pathways mature.

For growers and seed programs, the near-term role is pilot adoption under supervision – side-by-side with current methods, building local validation data before relying on CRISPR calls for commercial decisions.

Global vendor landscape: who offers what, and where

Growers can already source components for on-farm testing from established plant diagnostics companies and instrument makers. A non-exhaustive snapshot:

United States and Canada

Agdia (USA). Longstanding supplier of plant pathogen diagnostics. Portfolio includes ImmunoStrip® rapid tests for PVY and ELISA kits for PLRV, as well as AmplifyRP® (RPA-based) molecular kits for PVY that run quickly without full lab infrastructure. Distribution and technical support cover North America with global reach.
Biomeme (USA). Portable qPCR platforms with battery power and smartphone control. While widely used in wildlife, environmental, and medical settings, the same instruments and extraction kits can be adapted to plant pathogen assays developed by labs or partners. Useful for confirmatory testing where high sensitivity and quantitation are needed on site.
BIOREBA (Switzerland) via North American distributors. Although headquartered in Europe, BIOREBA’s qPCR kits – including duplex PLRV/PVY sets – are widely distributed and supported in North America. Suitable for lab and near-farm mobile lab setups.
Pocket Diagnostic (UK) via North American distributors. Lateral-flow PVY strips under the Pocket Diagnostic® brand are available through partners and online channels in Canada and the USA.

Europe (including UK)

BIOREBA (Switzerland). Broad catalogue of ELISA, PCR, and qPCR solutions for potato viruses; duplex kits for PLRV/PVY are a fit for mobile qPCR rigs or lab confirmation.
LOEWE Biochemica (Germany). Offers rapid on-site strips (LOEWE®FAST) for plant viruses and a wide range of ELISA and PCR kits, including PVY and PLRV. European distribution is strong, with availability into other regions via resellers.
OptiGene (UK). Maker of the Genie® series isothermal amplification instruments (LAMP), designed specifically for field robustness with sealed-tube fluorescence detection. The Genie III is commonly deployed by agriculture agencies and can run validated LAMP assays for bacterial soft rot species where available.
Pocket Diagnostic / Forsite Diagnostics (UK). PVY lateral-flow kits for fast triage in the field.
Fera Science (UK) and other accredited labs. While not on-farm kit vendors, these labs provide confirmatory PCR and sequencing options that pair well with field screening.

Australia and New Zealand

GeneWorks (Australia). Distributor and support partner for OptiGene Genie® instruments and LAMP workflows, including agricultural use. A practical route for Antipodean growers to source field-capable isothermal platforms.
Plant & Food Research (NZ) and regional labs. As with the UK, accredited lab partnerships are the backbone for confirmation and method validation.

Netherlands and broader EU

ClearDetections (Netherlands). Focused on molecular kits for plant pathogens (notably nematodes and the banana Fusarium TR4 pathotype). While potato virus kits are not the core here, the company illustrates the EU ecosystem supplying farm-adjacent molecular tools and DNA extraction kits for rugged use.

This landscape is evolving. For blackleg bacteria, LAMP assays validated in peer-reviewed studies are moving toward broader commercial access; regional diagnostics providers and universities often assist with assay transfer.

Growers should lean on local distributors and extension specialists to confirm which kits are validated for their area and which instruments are supported.

Practical sampling plans and QA: making farm data trustworthy

Portable diagnostics are only as good as the sampling plan behind them. Practical guidance for seed lots:

Define the unit. Treat each pallet or tote as a sampling unit. Pull subsamples across the stack, not just the face.
Sample size. For PVY/PLRV, 60–100 sprouts per lot (or per block within a large lot) gives useful prevalence estimates at low infection levels. For blackleg bacteria, 20–30 stem or cut-surface swabs per unit can reveal problematic clusters.
Avoid cross-contamination. Change gloves and blades between subsamples; move from “cleanest” to “riskiest” units; keep a bleach or peracetic solution at hand for tools and surfaces.
Controls. Run a positive control and a no-template control each session. Keep a small aliquot of original extract frozen or chilled for lab confirmation if a result will drive a commercial decision.
Documentation. Record lot IDs, sample positions, test type, kit lot numbers, and operator. Attach photos where helpful. This creates an audit trail if questions arise and accelerates continuous improvement.

Economics: where the ROI shows up

The direct costs of field testing – instruments, kits, consumables, labor – must be justified. In practice, returns accrue in four buckets:

Avoided downstream spread. Early removal or diversion of infected lots prevents the multiplicative costs of vector-mediated virus spread, mosaic hot spots, and downgraded progeny.
Reduced soft-rot losses. Identifying blackleg-risk lots pre-cutting allows sanitation and handling changes that prevent seed breakdown and rejections at delivery.
Better use of lab resources. Field screening focuses official submissions on suspect samples, reducing turnaround risk and potential resampling delays.
Buyer confidence. Documented on-farm screening that complements certification can be attractive to discerning buyers, especially under tight planting calendars.

A simple way to test the economics is to pilot on half your incoming lots for one season, track actions taken and outcomes, and compare losses and rejections to the untreated half. If the pilot yields even one averted high-prevalence PVY planting or prevents a blackleg flare-up in storage, the program often pays for itself.

Guardrails: limitations, training, and when to send to the lab

Three cautions keep on-farm DNA testing honest:

False confidence from poor sampling. A negative from a small, biased subsample does not mean the lot is clean. Invest in disciplined sampling.
Open-tube contamination. Isothermal methods can generate abundant amplicons. Favor sealed-tube workflows and physical separation between extraction and amplification.
Result interpretation. For borderline calls or when results will affect certification or contracts, confirm with an accredited lab. Keep the relationship with your lab strong – they are your backstop and method validation partner.

Training helps. Short operator courses on sampling, aseptic technique, and result logging dramatically improve data quality. Many vendors and extension programs provide practical SOPs; internal refreshers before planting season are cheap insurance.

What’s next: integrated panels, CRISPR cartridges, and data pipelines

The direction of travel is clear. Expect to see:

Multiplex field panels. Duplex and multiplex qPCR and isothermal panels that cover PVY/PLRV plus internal controls in one run, with ruggedized extraction that tolerates sprout sap.
CRISPR cartridges. Disposable, self-contained cartridges combining lysis, amplification, and CRISPR detection, with smartphone readouts. Early plant virus panels are the logical first wave.
Cloud-linked QA. Instruments that automatically log kit lot, temperature profiles, GPS, and operator ID, generating an encrypted record that can be shared with buyers or certification bodies as supplementary evidence.
Decision support. Threshold calculators that convert prevalence estimates to recommended actions – rogue, segregate, or reject – based on local aphid risk, weather, and variety.

The seed sector will still need accredited labs and field inspections. But the tempo of decisions is changing. Portable DNA tests pull crucial information forward in time, where it does the most good.

Companies and tools to explore by region (illustrative list)

North America

Agdia (USA): ImmunoStrip® for PVY and ELISA kits for PLRV; AmplifyRP® molecular kits for PVY suited to field workflows.
Biomeme (USA): Franklin® and other portable qPCR systems with battery power and smartphone interfaces; adaptable to plant assays for confirmatory testing.
Pocket Diagnostic (via distributors): PVY lateral-flow kits for quick, in-field triage.

Europe and UK

BIOREBA (Switzerland): qPCR kits including duplex PLRV/PVY sets; ELISA and PCR catalogue widely used in seed programs.
LOEWE Biochemica (Germany): LOEWE®FAST rapid strips for plant viruses; ELISA and PCR kits for PVY, PLRV.
OptiGene (UK): Genie® III LAMP instrument designed for outdoor use and sealed-tube fluorescence detection.
Pocket Diagnostic / Forsite Diagnostics (UK): Lateral-flow PVY tests.

Netherlands / EU

ClearDetections (Netherlands): Molecular diagnostic and extraction kits for plant pathogens (notably nematodes and Fusarium TR4); useful extraction workflows for field-adjacent work.

Australia / New Zealand

GeneWorks (Australia): Distribution and support for OptiGene Genie® LAMP instruments; regional technical support for agricultural deployments.

Before purchasing, growers should confirm local availability, validation status for intended targets, and after-sales technical support.

Bottom line

On-farm DNA diagnostics have crossed from promise to practice. When embedded in disciplined sampling and clear thresholds, they help seed growers act earlier and with more confidence. Use them to triage, not to certify; to trigger actions, not to decorate a file. Pair fast screening with accredited confirmation where it matters. Do that consistently, and you reduce hot spots, protect downstream crops, and keep quality momentum on your side.

Sources and further reading

Portable solutions for plant pathogen diagnostics – development, usage, and future potential (Frontiers in Microbiology, 2025). https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2025.1516723/full
Development of a robust, field-deployable LAMP assay for Dickeya detection (Peer-reviewed open access). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6590888/
Loop-mediated isothermal amplification assay for Dickeya and Pectobacterium – specificity and performance. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9649655/
Genome-informed LAMP for Pectobacterium parmentieri in potato. https://www.nature.com/articles/s41598-021-01196-4
One-step multiplex DiRT-PCR for PLRV, PVY and other potato viruses using diluted sap (Plant Disease, 2023). https://link.springer.com/article/10.1007/s10658-023-02722-y
Portable real-time microchip PCR for on-field plant pathogen detection (PLOS ONE). https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0082704
Agdia – PVY ImmunoStrip®, AmplifyRP® XRT PVY, and PLRV ELISA overview. https://orders.agdia.com/potato-test-kits
BIOREBA – qPCR PLRV/PVY duplex kit user guide (PDF). https://www.bioreba.ch/saas/CustomUpload/374O357O340O370O356O369O350O321O360O366O369O356O353O352O350O320O326O/qPCR_PLRV_PVY_User_Guide.pdf
LOEWE Biochemica – PVY kits and LOEWE®FAST rapid tests. https://loewe-info.com/category-loewefast-rapid-tests-plant-viruses/ and https://loewe-info.com/product/potato-y-potyvirus-pvy/
Pocket Diagnostic® – PVY lateral-flow rapid test. https://www.pocketdiagnostic.com/product/potato-virus-y-test/
OptiGene – Genie® III field-portable LAMP instrument. https://www.optigene.co.uk/instruments/genie-iii/
Genie® III distribution in Australia (GeneWorks). https://geneworks.com.au/OPG-GEN3-01/
Biomeme – portable qPCR platforms and applications. https://biomeme.com/applications/infectious-disease
Next-generation methods for early disease detection in crops (Pest Management Science, 2023). https://onlinelibrary.wiley.com/doi/10.1002/ps.7733
Review: CRISPR-Cas-assisted diagnostics for plant viruses (Virology, 2024). https://pubmed.ncbi.nlm.nih.gov/38955083/
Dickeya solani – a critical quarantine pathogen in potato (Microbiology Spectrum, 2025). https://journals.asm.org/doi/10.1128/spectrum.00784-24
PCR macroarray potato virus kit (multiplex virus panel overview; PDF). https://www.diamet.lv/files/PCR_CA–GO–2102EN.pdf
USDA-NIFA project page – diagnostics development and blackleg outreach context. https://portal.nifa.usda.gov/web/crisprojectpages/1012737-development-of-multiplex-detection-methods-and-management-tools-for-dickeya-dianthiocola-on-potato.html

Note: CRISPR-based plant pathogen diagnostics are advancing quickly. Growers considering early pilots should coordinate with their accredited lab or extension service to ensure local validation and appropriate interpretation before using results for commercial decisions.

Author: Lukie Pieterse, Potato News Today
Cover image: Credit Alexei from Pixabay