Présentation de F. Joudelat Congrès IIRB février 2024

1. François Joudelat – 79th IIRB Congress
1
MANAGING CERCOSPORA WITH MODELING
AND IOT CAMERAS
CERCOCAP project

2. 2
Cercospora Leaf Spot management
• Concerning disease
• Advice for the beet sector :
– Cultural practices
– Spray timing
• Different points of view :
– farmers, industries, public policies, …
 Prototyping decision support tools

3. 3
CERCOCAP : a research project
Decision
support
Modeling +
assimilation
IoT cameras +
image
processing
Trials +
expertise

4. 4
Data available
• > 10 years of trials + monitoring
• 8km grid, daily weather reanalysis
• Several thousands of beet leaves images
Thanks everyone !

5. 5
First approaches
• Daily Infection Values sum : simple but imprecise
• Correlated weather variables
– Relative humidity not very significant
incidence
∑DIV

6. 6
Advanced approaches
• Linear Regressions : mitigated results
• Machine Learning (decision trees) : best results but more complex
 Complexity-accuracy tradeoff
accuracy

7. 7
Assisting monitoring
• Monitoring network
• IoT cameras
– 3G
– 8MP
• Disease quantification
 Goal : automated disease monitoring

8. 8
Technology improvements
• 2019 :
– robot 1MP images
– Color + texture segmentation
• 2020 : 5MP
– Unet segmentation
• 2023 : 8MP
– Image augmentation
– Segment Anything Model

9. 9
Algorithm optimization
• Size optimization
• Collaborative annotations
• Data augmentation
• Efficient retraining strategy
– Dimension reduction
– Outlier detection
• Software integration
Margin of improvement
F1≈0,63

10. 10
Assimilation for better accuracy
“Data assimilation is a mathematical discipline that seeks to optimally
combine theory […] with observations.” Wikipedia
• Observation @ j-7 as a covariable
• Simulation from time series
 Great improvement
on explained variance
Forecast Assimilation R²
(% variance
explained)
MAE
(mean error)
14 days no 39 10
14 days yes 87 4
7 days no 36 10
7 days yes 93 3

11. 11
Limits + perspectives
• Best models are black boxes
– Role of weather variables ?
– Collinerarity & interactions
• Future stakes : pathogen-host interactions
– New highly tolerant varieties
– Cercospora strains + virulence (ITB project « SUGAR »)
• A great part of variance remains unexplained
– Microclimate / Inoculum / Chaotic process ?
Model-only approach will not work in every situation
• Maintaining an IoT network is not « setup and forget »
• Deep learning is great for image analysis but struggles with small symptoms

12. 12
Thank you for your attention
+ time for questions