Options
June 1, 2023
Journal Article
Title
Digital phytoplasmology: Remote sensing of fruit tree phytoplasma diseases
Abstract
Apple proliferation (AP) and pear decline (PD) are important diseases of fruit trees in Europe that are difficult to control. Timely uprooting of infected trees is a successful measure to limit the spread of the diseases and is therefore mandatory in some production areas. Large-scale monitoring strategies are required. AP and PD induce in infected trees an early leaf reddening in late summer or early autumn, which is suitable to be monitored by remote sensing. Investigations were carried out to find applicable strategies for remote sensing of AP and PD in the heavily affected fruit-growing region of Palatinate in Southwest Germany. In 2019-2022, more than 20,000 apple trees and more than 6,300 pear trees were monitored for partial or entire leaf reddening. A very high correlation to AP was found according to specific symptom recording and PCR testing of ‘Candidatus Phytoplasma mali’ and a high correlation to PD according to PCR testing of ‘Ca. P. pyri’. Hyperspectral images from infected and healthy leaves of apple and pear were analysed and specific spectral differences were identified. Remote sensing of AP-and PD-infected trees, respectively, was achieved by drone flights with hyperspectral or multispectral cameras in reference orchards. To upscale the remote sensing, multispectral satellite images covering the region of the reference orchards were analysed and AP-and PD-infected trees, respectively, could be identified. The accuracy of remote sensing relies on the timing when phytoplasma-induced leaf reddening appears before leaf fall in autumn.
Author(s)