Monitoring of western corn rootworm damage in maize fields by using integrated radar (ALOS PALSAR) and optical (IRS LISS, AWiFS) satellite data
Gizella Nádor(1), Diána Fényes(1), György Surek(2) and László Vasas(3)
(1) Inst. of Geodesy, Cartography and Remote Sensing, Bosnyák tér 5, H-1149 Budapest, Hungary
(2) MLOG Ltd., Bercsényi Miklós u. 95/A, H-1154 Budapest, Hungary
(3) Agricultural Office of County Békés, Szarvasi út 79/1, H-5600 Békéscsaba, Hungary
The gradual dispersion of western corn rootworm (WCR) is becoming a serious maize pest in Europe, and all over the world. The WCR was introduced to Europe from the USA. First it was detected in Europe near Beograd in 1992.
In 2007, FÖMI RSC analyzed WCR larval damage identified by experts of Agricultural Office of County Békés on two infected and two WCR free maize parcels using remote sensing methods. The structure of a healthy, WCR free maize field shows straight rows in a clear order and upstanding maize stalks.The WCR infection causes “gooseneck” lodging, wilted broken corn-stalks laid randomly over the ground. The damage itself results in physical and visible disorder in the maize field. Our goal is to assess and identify the disorder and structural changes caused by WCR using polarimetic radar images (ALOS PALSAR) after identifying of the maize fields using optical (IRS LISS, AWiFS) satellite time series.
This project is implemented in 2008 in the framework of our approved tender called by the Hungarian Space Office and with the support of the Ministry of Environment and Water. This project was submitted to ESA and the contract for the “Utilization of ESA Data under Category-1 scheme” was signed in 2 April 2008 (ESA EO CAT-1 5162). It assigned a quota of 74 ALOS PALSAR and 30 ENVISAT ASAR radar satellite image data for the project at reproduction cost. This project involves the reference data collection, the quantitative evaluation of radar (ALOS PALSAR) and optical (IRS LISS, AWiFS) satellite data time series focused on damage identification caused by WCR and the quality control of the thematic results including field survey. The applied methods for radar data processing are as follows: focusing, multi-looking, radiometric calibration, orthorectification, speckle filtering, polarimetric decomposition (Eigenvector-Eigenvalue based decomposition), classification methods (H-A- segmentation) and extraction of polarimetric descriptors which characterize the structure of the maize fields (ordered or disordered state).
The objective of this project is unique in EU. Based on the first results, introduction of radar polarimetry increased significantly the accuracy. The further development of this technology will create the possibility to accomplish a more accurate damage identification system. The amount of information can be used efficiently in plant protection; moreover can be useful for farmers, pesticide producers, state authorities and research institutes.