Chestnut health monitoring by aerial photographs obtained by unnamed aerial vehicle

Abstract

The Chestnut ink disease (Phytophthora cinnamomi) and the chestnut blight (Cryphonectria parasitica) are the diseases that cause more damage to European chestnut (Castanea sativa). After two decades from the first occurrence of chestnut blight in Portugal, the hypovirulence began to be observed in some locations. The population of these strains is characterized by low diversity. Many of the sub-populations belong only to the EU-11 group, which appears only in some orchards in Italy. Successful treatment depends on the way the population of the fungus extends into the area to be treated. This study refers to the monitoring of chestnut decline, by aerophotogrammetric flights, covering 231 ha in the Padrela region (Valpaços). Unmanned Aerial Vehicle (UAV) eBee (Sensefly) was used and color and near infrared (NIR) aerial photographs were obtained. Those photographs were compared to aerial images taken in a national flight in 2006. During the period between 2006-2014 new chestnuts plantations occurred (11%), nevertheless the area covered by chestnut decreased. In 129 ha (56%) the chestnut decline increased. The biotic agents were the principal causes of the C. sativa decline, which was confirmed by field observations.