Researchers from North Carolina State University in the United States have developed an electronic patch that can be applied to the leaves of plants to monitor crops for different pathogens – such as viral and fungal infections – and stresses such as drought or salinity. In testing, the researchers found the patch was able to detect a viral infection in tomatoes more than a week before growers would be able to detect any visible symptoms of disease.
The technology builds on a previous prototype patch, which detected plant disease by monitoring volatile organic compounds (VOCs) emitted by plants. Plants emit different combinations of VOCs under different circumstances. By targeting VOCs that are relevant to specific diseases or plant stress, the sensors can alert users to specific problems.
“This is important because the earlier growers can identify plant diseases or fungal infections, the better able they will be to limit the spread of the disease and preserve their crop,” says Qingshan Wei, corresponding author of a paper on the work and an assistant professor of chemical and biomolecular engineering at NC State. “In addition, the more quickly growers can identify abiotic stresses, such as irrigation water contaminated by saltwater intrusion, the better able they will be to address relevant challenges and improve crop yield.”
The patches themselves are small – only 30 millimetres long – and consist of a flexible material containing sensors and silver nanowire-based electrodes. The patches are placed on the underside of leaves, which have a higher density of stomata – the pores that allow the plant to ‘breathe’ by exchanging gases with the environment.
“The new patches incorporate additional sensors, allowing them to monitor temperature, environmental humidity, and the amount of moisture being ‘exhaled’ by the plants via their leaves,” adds Yong Zhu, co-corresponding author of the paper and Andrew A. Adams Distinguished Professor of Mechanical and Aerospace Engineering at NC State.
The researchers say they are two steps away from having a patch that growers can use. First, they need to make the patches wireless – a relatively simple challenge. Second, they need to test the patches in the field, outside of greenhouses, to ensure the patches will work under real-world conditions.