Feasibility of Little Cherry Disease/X-disease detection in Prunus avium using field asymmetric ion mobility spectrometry

Authors: KOTHAWADE, GAJANAN - Washington State University; KHOT, LAV - Washington State University; CHANDEL, ABHILASH - Virginia Tech; MOLNAR, CODY - Washington State University; HARPER, SCOTT - Washington State University; Wright, Alice

Submitted to: IEEE Sensors Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Little cherry disease/X-disease (LCD/XD) is present in Pacific Northwest sweet cherry (Prunus avium) orchards. LCD/XD detection is by visual scouting and/or molecular testing. Visual symptoms only appear near harvest making visual scouting inefficient. Testing is expensive and demands skilled resources. This study examines a field asymmetric ion mobility spectrometry (FAIMS) system for detecting LCD/XD in sweet cherry trees after harvest. Samples were taken from different orchards in central Washington. These were then placed in 1-gallon glass jars for volatile headspace accumulation. The headspace was analyzed using the FAIMS system. Molecular testing was done to determine disease presence. Volatiles of infected trees had higher ion currents than healthy trees (p < 0.05). FAIMS had 68 – 83% accuracy for LCD/XD positive and negative samples. Plotting the ion currents also showed a clear difference between the infected and healthy trees. A portable FAIMS system was able to detect LCD/XD in sweet cherry. This may one day allow for screening many trees quickly and cheaply. This will help growers choose which trees to remove.

Technical Abstract: Little cherry disease (LCD)/X-disease has been critically affecting the Pacific Northwest sweet cherry (Prunus avium) industry. Current LCD/X-disease detection relies on visual scouting and/or molecular analysis. Visual symptoms that only appear around fruit maturity render visual scouting to be inefficient while molecular analysis is costlier and demands skilled resources. This study evaluates suitability of a field asymmetric ion mobility spectrometry (FAIMS) system for the detection of LCD/X-disease infection in sweet cherry cultivars, namely Benton, Cristalina, and Tieton, at post-harvest growth stage. A total of 37 samples of stem cuttings with leaves were collected from different commercial orchards in central Washington and from greenhouse collections and then transferred to 1-gallon glass jars for volatile headspace accumulation. The headspace was analyzed using FAIMS system at an average flow rate of 1.5 L/min and pressure of 50 kPa. Simultaneously, molecular analyses were conducted on the samples to extract titer levels and phytoplasma copies to confirm positive and asymptomatic samples. Higher ion currents pertained to volatiles of infected samples compared to asymptomatic (healthy unknowns) (p < 0.05). Such discrimination was prominent at derived FAIMS’s ion current features at different compensation voltage (CV)-dispersion field (DF) ranges of -3–3 V and 20–98 %. The RF and NB classifiers achieved 68 – 83% classification accuracy for LCD/X-disease positive and asymptomatic samples. The ion currents plotted at the dispersion field from the selected range also confirmed a clear distinction between the infected and healthy samples. Cultivar-specific variation in the ion current spectra was observed in all the samples. Cumulatively, a portable FAIMS system was found suitable for detecting LCD/X-disease symptoms in sweet cherry cultivars. This research attempts to propose a methodology to evaluate LCD/X-disease-linked volatiles using a partially destructive method on a small scale. Future studies need to be conducted in controlled and field environments for refinement and revalidation for disease detection and initiation of orchard management decisions.