Assessment of the Spread of Chestnut Ink Disease from 1995 to 2005 Using Aerial Photography and Geostatistical Methods

摘要

Chestnut ink disease, caused by Phytophthora cinnamomi and P. cambivora, is responsible for important economic losses and it limits the establishment of new chestnut (Castanea sativa) groves in Portugal. Differences in soil properties and in cropping practices affect the ink severity, and differences on levels of attacks can be assessed by remote sensing. In this study data for monitoring C. sativa decline was selected using field surveys and aerial photography: Near-infrared images obtained in 1995 and normal and false color images obtained in 2005. The spatial distribution of ink disease in Northern Portugal for the years 1995-2005 was estimated through kriging interpolation. From 1995 to 2005 chestnut area in Portugal declined due to the fact that new plantations (15.0%) were not sufficient to replace chestnut mortality (26.9%). The foci and the spread of the disease have increased since 1995. Also, the average damage level has significantly different in observations for the two dates.