Detection of multi-tomato leaf diseases (late blight, target and bacterial spots) in different stages by using a spectral-based sensor

Authors

Jinzhu Lu, Xihua UniversityFollow
Reza Ehsani, University of California, Merced
Yeyin Shi, University of Nebraska-LincolnFollow
Ana Isabel de Castro, Institute for Sustainable Agriculture
Shuang Wang, Xihua University

Document Type

Article

Date of this Version

2018

Citation

Scientific Reports | (2018) 8:2793 | DOI:10.1038/s41598-018-21191-6.

Comments

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License.

Abstract

Several diseases have threatened tomato production in Florida, resulting in large losses, especially in fresh markets. In this study, a high-resolution portable spectral sensor was used to investigate the feasibility of detecting multi-diseased tomato leaves in different stages, including early or asymptomatic stages. One healthy leaf and three diseased tomato leaves (late blight, target and bacterial spots) were defined into four stages (healthy, asymptomatic, early stage and late stage) and collected from a field. Fifty-seven spectral vegetation indices (SVIs) were calculated in accordance with methods published in previous studies and established in this study. Principal component analysis was conducted to evaluate SVIs. Results revealed six principal components (PCs) whose eigenvalues were greater than 1. SVIs with weight coefficients ranking from 1 to 30 in each selected PC were applied to a K-nearest neighbor for classification. Amongst the examined leaves, the healthy ones had the highest accuracy (100%) and the lowest error rate (0) because of their uniform tissues. Late stage leaves could be distinguished more easily than the two other disease categories caused by similar symptoms on the multi-diseased leaves. Further work may incorporate the proposed technique into an image system that can be operated to monitor multi-diseased tomato plants in fields.