# _remote sensing_
## 2 Materials and Methods
### Crop Diseases Detection Methods  
#### 2.2.1 Orchards Diseases Detection  
In the last few years, urgency has emerged to develop methods for monitoring orchards' status, since tools capable of providing a periodic assessment on the decline of trees due to their diseases were unavailable. By thoroughly observing the most widely used land cover map in Europe, i.e., the Corine Land Cover (CLC), it was noticed that there was an increase in olive groves from 2012 to 2018, notwithstanding the remarkable reduction of thousands of hectares of area covered by olive trees in some Italian provinces (e.g., Lecce province) due to the _Xylella fastidiosa_ disease ([[https://ec.europa.eu/jrc/en/science-update/monitoring-impacts-xylella-fastidiosa](https://ec.europa.eu/jrc/en/science-update/monitoring-impacts-xylella-fastidiosa)]([https://ec.europa.eu/jrc/en/science-update/monitoring-impacts-xylella-fastidiosa](https://ec.europa.eu/jrc/en/science-update/monitoring-impacts-xylella-fastidiosa)) accessed on 12 July 2021). In New Zealand's, instead, kiwifruit industry in 2010 was hit by _Pseudomonas syringae pv. Actinidae_ (Psa) [42; 43; 44] and the relative costs for this industry were estimated to be around USD 126  million in 2012, with an ongoing cost for the next 15 years between USD 740 to USD 885 million [42]. Within this context, this study is mainly devoted to describe an approach based on Earth Observation satellite images and a neural network (NN) for detecting the Psa pathogen effects on kiwi trees. Different, and rather far, areas of interest (Figure 2) were considered in this analysis. The following study areas were considered: the Te Puke and Takaka areas in New Zealand and the Agro Pontino area in the Italian region of Lazio, where the climate is characterized by annual rainfall between 800 and 1000 mm per year, with abundant rainfall in the autumn season and an arid period between June and August. In 2019, the kiwi tree areas affected by Psa experienced a long cold season accompanied by rain, creating favorable conditions for the proliferation of this particularly aggressive bacterium. The virus was spreading very rapidly, creating alarm for this crop of great economic value: over 30% of the Italian national production is in the Lazio Region. The reference study areas for the Psa cases, to which NN must be applied by training, testing and validation, were selected in the surroundings of the Te Puke and Takaka regions (Figure 2). These two regions cover more than 1200 orchards' areas with validated data on the infected and non-infected fields according to 2019 statistics by the Kiwifruit Vine \begin{table}
\begin{tabular}{l c c c} \hline
**Parameter** & **Meaning** & **Mean** & **Range 1** & **Source** \\ \hline SALB & Soil albedo & 0.16 & [41] \\ SWCON & Profile drainage coefficient (soil water conductivity) & 0.90 & [41] \\ MxRWU & Max root water uptake (cm\({}^{3}\) water cm\({}^{-1}\) root) & 0.0035 & [41] \\ SAT & Saturation water content (cm\({}^{3}\) cm\({}^{-3}\)) & 0.479 & Pedotransferer from ESDAC-JRC soil maps. \\ DUL & Drained upper limit (cm\({}^{3}\) cm\({}^{-3}\)) & 0.240 & Differences of values for the same soil \\ LL & Lower limit (cm\({}^{3}\) cm\({}^{-3}\)) & 0.115 & water limit across fields were minimal \\ AirDry & Residual humidity (cm\({}^{3}\) cm\({}^{-3}\)) & 0.055 & (\(<\)0.03 cm\({}^{3}\) cm\({}^{-3}\)) \\ \hline \end{tabular}  
* For calibration and data assimilation.  
\end{table} 
Table 1: _Cont._  
Figure 2: Study areas in New Zealand: Takaka region (**A**)-Te Puke region (**B**), and in Italy: Cisterna di Latina (**C**). Health Inc. (KWH), a leading biosecurity organization dedicated to supporting the New Zealand kiwifruit industry. The NN was trained in the first stage with a set of images for the period 2010 to 2012 considering previous research carried out [45] for the Te Puke region. In the second stage, the procedure followed was applied by testing and validation of orchards located in Takaka region (South Island), where no cases of Psa outbreaks were registered.