ATR-IR spectroscopy for early detection of strawberry powdery mildew
A rapid, non-destructive detection method using ATR-IR spectroscopy to identify powdery mildew infection in strawberry leaves at an early stage, before visible symptoms appear. The technology uses specific IR peak ratios to enable timely disease management, potentially saving significant crop losses.
Overview
Strawberry powdery mildew, caused by Sphaerotheca macularis, is a major fungal disease responsible for over 1 billion CNY in annual losses across China's 154,000+ hectares of strawberry cultivation. The pathogen spreads rapidly because visible symptoms (white spots) only appear approximately seven days after initial infection, by which time containment becomes difficult. This research offers an early detection solution using Attenuated Total Reflectance-Infrared (ATR-IR) spectroscopy to identify infection before symptoms are visible to the naked eye, enabling growers to intervene proactively and reduce crop losses.
Technical specifications
Detection method:
- ATR-IR spectroscopy is applied directly to strawberry leaves at room temperature (23±1 °C)
- The 1703 cm⁻¹ spectral peak serves as a reliable indicator of pathogen presence during early infection stages
- The peak area ratio of 1703/2920 cm⁻¹ is calculated on both sides of strawberry leaves
- A fitting curve (y = -0.0192x² + 0.1036x - 0.0809, R² > 0.90) quantifies infection progression
Validation status:
- Tested on 10 healthy and 30 infected strawberry leaves across four infection stages
- Spectra are normalized for quantitative analysis of peak area ratios
- Non-destructive measurement preserves leaf integrity during testing
Development roadmap:
- Design of a portable infrared spectrometer within one year of funding
- Improved accuracy of IR peak intensity measurements (approximately six months)
- In-situ field testing planned after equipment development
Technology readiness level
The technology is currently at TRL 3–4 (analytical proof-of-concept to laboratory validation). Laboratory experiments have confirmed the correlation between the 1703 cm⁻¹ peak and early-stage infection, with consistent results across multiple leaf samples and infection stages. The next phase involves developing a portable spectrometer for field deployment and conducting in-situ tests with industry partners. The research team is actively seeking partners to support equipment testing and validation in real-world agricultural settings. Collaborative opportunities exist for co-development of the portable device, sponsored research, and pilot trials to advance the technology toward commercial readiness.
About Nanjing Agricultural University
Nanjing Agricultural University is a public research university with an agricultural focus in Nanjing, advancing national and regional priorities through integrated basic-to-applied research and field training. Industry engages through experimental farms, field stations, controlled-environment facilities, and pilot processing spaces for prototyping and scale‑up. An industry liaison team supports sponsored research, testing services, and joint labs, while regional demonstration sites speed on‑farm trials across the Yangtze River Delta. Research is supported by national and provincial programs, including the National Natural Science Foundation of China and the Ministry of Science and Technology. A technology transfer office manages IP, licensing, and startup incubation.
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