Comparative evaluation of lateral flow immunoassays, LAMP, and quantitative PCR for diagnosis of fire blight in apple orchards

Fire blight remains a serious threat to commercial apple production in the USA and worldwide. Other diseases and spray damage can result in fire blight-like symptoms that can lead to misdiagnosis and affect disease management strategies. Accurate and timely detection of the fire blight pathogen,Erwinia amylovora, is extremely important to deploy appropriate and timely measures to reduce fire blight epidemics in commercial apple orchards. We tested two commercial lateral flow immunoassays (AgriStrip (R), and Pocket Diagnostics kit), Loop mediated isothermal amplification (LAMP), and quantitative PCR (qPCR) to diagnoseE. amylovorainfected samples in lab and field settings. The AgriStrip (R) and Pocket Diagnostics kits were able to detect actively growing bacteria up to x10(6)cfu/ml bacterial concentration. Pocket Diagnostics kit had less specificity and showed positive tests forE. pyrifoliain addition toE. amylovora. The LAMP assay showed high specificity forE. amylovoraand was able to detect up to x10(3)cfu/ml bacterial concentrations. The qPCR assay was also able to detect bacterial cells up to x10(-3)cfu/ml bacterial concentration with highly specificE. amylovoradetection. Grower surveys and comparative cost-benefit analysis indicated that immunoassay kits are less expensive, easier to use, and require less technical expertise for on-site fire blight diagnosis than LAMP and qPCR. However, the choice of a specific diagnostic assay depends on the time, sensitivity, and specificity required for the detection of fire blight and its management.

Automated summary

This study compared different diagnostic methods for fire blight, revealing that lateral flow immunoassays are more cost-effective and user-friendly for on-site fire blight diagnosis than LAMP and qPCR.