Инструментальный мониторинг дехромации листвы каштана конского обыкновенного при повреждении охридским минером

Abstract

A comparison of the visual and instrumental assessments of the horse chestnut foliar dechromation degree infested by the Ohrid miner (Cameraria ohridella) was carried out. The data of surveys of model trees for the period 2014–2022 in the Moscow region are compared. A statistically reliable regression relationship between the results of visual and instrumental assessment of dechromation in a long-term series of observations is shown. Instrumental monitoring of the leaves damages during the growing season was carried out based on the assessment of the NDVI vegetation index using the GreenSeeker Handheld® (Trimble) device. The seasonal dynamics of the NDVI index of foliage under Ohrid miner damage is presented on the example of the 2021 season. It is shown that the plants affected by the pest have a shorter growing season, and the average NDVI index for the season is 25...30 % lower than that of undamaged plants. In a nine-year series of observations, it was found that the transition of the NDVI index over the threshold value of 0.4 in plants affected by the Ohrid miner is observed on average 30...40 days earlier than in healthy plants. The possibility of assessing foliage dechromation based on the results of hyperspectral imaging without visualization using the Ocean Insight «Flame» spectrometer is considered. It is shown that the spectral characteristics of the reflectivity of healthy and damaged Ohrid miner leaves differ significantly, which was demonstrated by comparing the spectral brightness curves of reflection. Characteristic spectral zones in the visible and near infrared ranges have been identified, according to which the presence of leaf damage by a miner is successfully identified. It was found that in the near-infrared radiation area, the reflection of damaged leaves are significantly lower than that of healthy leaves, which indicates a decrease in the overall water content of chestnut leaf blades when damaged by pests. According to the results of multi- and hyperspectral surveys, it is possible to automatically determine the lesion of the horse chestnut foliage by the leaf-mining pest Cameraria ohridella.