Paper · 2026 · Smart Agricultural Technology

Early detection of plant pathogens in the asymptomatic phase: A scoping review of hyperspectral imaging combined with machine learning

Weiqun Wang; Shirin Ghatrehsamani

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26
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0
citations
2
research areas
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Open access · cc-by-nc-nd

Abstract

• First PRISMA-ScR mapping of 79 HSI-ML asymptomatic detection studies (42 species, 74 pathogens) • Controlled-to-field accuracy gap quantified: 91.4% vs. 86.3% (5.1 pp, p = 0.0163 ) • 56.8% of studies omit temporal sampling documentation (CV = 139%) • SWIR underutilization (11.8%) reflects economic, not scientific, barriers • DBVS proposed as standardized temporal metric for cross-study comparability Plant disease management requires non-invasive detection methods capable of identifying infections before visible symptom manifestation, thereby enabling timely intervention. Hyperspectral imaging combined with machine learning and deep learning (HSI-ML) achieves 90.2% classification accuracy in controlled environments for asymptomatic plant detection; however, systematic characterization of methodological practices across this rapidly expanding field remains absent. This PRISMA-ScR compliant scoping review mapped 79 peer-reviewed studies (2010–2025) encompassing 42 plant species and 74 pathogenic agents using a Population-Concept-Context framework. Visible-near-infrared (VNIR) systems dominated deployment (61.8%, n = 49 ), while short-wave infrared (SWIR) systems remained substantially underutilized (11.8%, n = 9 ) due primarily to economic rather than scientific constraints. Among 67 unique algorithms identified, machine learning methods accounted for 30.7% (SVM, random forests, and PLS-DA predominant), whereas deep learning represented 28.4% (2D-CNN, 3D-CNN, and hybrid architectures). Critical methodological gaps emerged: 56.8% of studies omitted temporal sampling documentation (detection latency range: 1–56 days post-inoculation; coefficient of variation = 139%). Platform-stratified analysis revealed controlled environments achieved 91.4% ± 6.6% classification accuracy ( n = 48 ) versus 86.3% ± 9.1% for field/UAV deployments ( n = 26 ), representing a significant 5.1 percentage-point performance decrease ( p = 0.0163 ). Detection accuracy exhibited a weak negative correlation with detection timing ( ρ = − 0.33 , p = 0.067 ), though this association did not reach conventional statistical significance. Methodological heterogeneity—rather than algorithmic limitations—constitutes the primary barrier to field operationalization. Adoption of Days Before Visible Symptoms (DBVS) as a standardized temporal metric could resolve an estimated 40–50% of cross-study variance currently attributed to inconsistent asymptomatic-phase definitions.

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Claims 12

Observationobservedoriginal resultmeasured

Claim · model-written summary

VNIR systems were the dominant sensor type in the reviewed asymptomatic detection studies (61.8%)

Taxon
plant speciese0
Outcome
Visible-near-infrared (VNIR) systemse1
Value
61.8%e1
Qualifier
n = 49e1

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e1

“Visible-near-infrared (VNIR) systems dominated deployment (61.8%, n = 49 )”

✓ located verbatim in the source · abstract, characters 1063–1137 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

SWIR systems were substantially underutilized (11.8%), mainly for economic rather than scientific reasons

Taxon
plant speciese0
Outcome
short-wave infrared (SWIR) systemse1
Value
11.8%e1
Qualifier
due primarily to economic rather than scientific constraintse1

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e1

“short-wave infrared (SWIR) systems remained substantially underutilized (11.8%, n = 9 ) due primarily to economic rather than scientific constraints”

✓ located verbatim in the source · abstract, characters 1145–1293 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

Machine learning methods accounted for 30.7% of the algorithms identified

Taxon
plant speciese0
Outcome
machine learning methodse1
Value
30.7%e1
Qualifier
SVM, random forests, and PLS-DA predominante1

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e1

“machine learning methods accounted for 30.7% (SVM, random forests, and PLS-DA predominant)”

✓ located verbatim in the source · abstract, characters 1334–1424 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

Deep learning accounted for 28.4% of the algorithms identified

Taxon
plant speciese0
Outcome
deep learninge1
Value
28.4%e1
Qualifier
2D-CNN, 3D-CNN, and hybrid architecturese1

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e1

“deep learning represented 28.4% (2D-CNN, 3D-CNN, and hybrid architectures)”

✓ located verbatim in the source · abstract, characters 1434–1508 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

Of the reviewed studies, 56.8% did not document temporal sampling

Taxon
plant speciese0
Outcome
temporal sampling documentatione1
Value
56.8%e1

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e1

“56.8% of studies omitted temporal sampling documentation”

✓ located verbatim in the source · abstract, characters 1548–1604 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

Detection latency varied widely across studies, with a coefficient of variation of 139%

Taxon
plant speciese0
Outcome
detection latencye1
Value
1–56 days post-inoculatione1
Qualifier
coefficient of variation = 139%e1

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e1

“detection latency range: 1–56 days post-inoculation; coefficient of variation = 139%”

✓ located verbatim in the source · abstract, characters 1606–1690 · show in text ↑
Method / resourceobservedoriginal resultmeasured

Claim · model-written summary

In controlled environments, HSI-ML classification accuracy averaged 91.4% ± 6.6%

Taxon
plant speciese0
Outcome
classification accuracye1
Value
91.4% ± 6.6%e1
Setting
controlled environmentse1

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e1

“controlled environments achieved 91.4% ± 6.6% classification accuracy ( n = 48 )”

✓ located verbatim in the source · abstract, characters 1731–1811 · show in text ↑
Method / resourceobservedoriginal resultmeasured

Claim · model-written summary

In field and UAV deployments, HSI-ML classification accuracy averaged 86.3% ± 9.1%

Taxon
plant speciese0
Outcome
classification accuracye2
Value
86.3% ± 9.1%e2
Setting
field/UAV deploymentse2

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e2

“classification accuracy ( n = 48 ) versus 86.3% ± 9.1% for field/UAV deployments ( n = 26 )”

✓ located verbatim in the source · abstract, characters 1777–1868 · show in text ↑
Method / resourceobservedoriginal resultnegativesignificant (as stated)measured

Claim · model-written summary

Field and UAV deployments showed a significant 5.1 percentage-point decrease in classification accuracy compared with controlled environments

Taxon
plant speciese0
Outcome
classification accuracye2
Direction
decreasee3
Value
5.1 percentage-pointe3
Qualifier
p = 0.0163e3
Comparator
controlled environmentse1
Setting
field/UAV deploymentse2

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e1

“controlled environments achieved 91.4% ± 6.6% classification accuracy ( n = 48 )”

✓ located verbatim in the source · abstract, characters 1731–1811 · show in text ↑
e2

“classification accuracy ( n = 48 ) versus 86.3% ± 9.1% for field/UAV deployments ( n = 26 )”

✓ located verbatim in the source · abstract, characters 1777–1868 · show in text ↑
e3

“representing a significant 5.1 percentage-point performance decrease ( p = 0.0163 )”

✓ located verbatim in the source · abstract, characters 1870–1953 · show in text ↑
Associationobservedoriginal resultno effectnot significant (as stated)measured

Claim · model-written summary

Detection accuracy showed a weak negative correlation with detection timing, not statistically significant

Taxon
plant speciese0
Outcome
Detection accuracye1
Direction
negativee1
Value
ρ = − 0.33e1
Qualifier
p = 0.067e1
Comparator
detection timinge1

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e1

“Detection accuracy exhibited a weak negative correlation with detection timing ( ρ = − 0.33 , p = 0.067 ), though this association did not reach conventional statistical significance”

✓ located verbatim in the source · abstract, characters 1955–2137 · show in text ↑
Recommendationhypothesisoriginal resultpositivebasis n/a

Claim · model-written summary

Adopting Days Before Visible Symptoms (DBVS) as a standardized temporal metric could resolve an estimated 40–50% of cross-study variance

Taxon
plant speciese0
Outcome
Days Before Visible Symptoms (DBVS) as a standardized temporal metrice1
Value
40–50%e1
Qualifier
an estimatede1

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e1

“Adoption of Days Before Visible Symptoms (DBVS) as a standardized temporal metric could resolve an estimated 40–50% of cross-study variance”

✓ located verbatim in the source · abstract, characters 2265–2404 · show in text ↑
Mechanismauthor interpretationoriginal resultbasis n/a

Claim · model-written summary

Methodological heterogeneity, rather than algorithmic limitations, is the primary barrier to field operationalization of HSI-ML

Taxon
plant speciese0
Outcome
primary barrier to field operationalizatione1
Qualifier
Methodological heterogeneitye1

Verbatim

e0

“encompassing 42 plant species and 74 pathogenic agents”

✓ located verbatim in the source · abstract, characters 962–1016 · show in text ↑
e1

“Methodological heterogeneity—rather than algorithmic limitations—constitutes the primary barrier to field operationalization”

✓ located verbatim in the source · abstract, characters 2139–2263 · show in text ↑