## 2 Materials and Methods  
In the framework of the European Union Horizon 2020 BIOVEXO project, during the summer of 2023, when the temperature ranged between 29 and 34 \({}^{\circ}\)C, a field survey was conducted in two orchards located on Mallorca Island, where _Xf_n (harboring the genotypes ST7 and ST81 [11, 22]) was detected. Figure 1A-C shows the most representative symptoms induced by _Xf_ on almond trees. During the field survey in Mallorca (Balearic Islands) in July 2023, a total of 53 almond trees were randomly sampled from the two orchards having different planting ages and plantation plots (Table 1). All the samples used in the experiment consisted of chips from semi-ignified shoots. In detail, five young shoots per tree were collected from the basal branches, sometimes close to ALS symptoms when these were evident, but not yet senescent or desiccated. Plant material was stored in plastic bags and put in a refriger  
Figure 1: **(A)** Infected almond tree in Mallorca orchard with ‘golden death’ symptoms; **(B)** scorch symptoms on almonds with the typical yellow band, marked with a red arrow; and **(C)** on the leaf tissue between the green and dead areas. \begin{table}
\begin{tabular}{l c c} \hline \hline
**Sample No.** & **Average Cq Values** & **cLAMP Result** \\ \hline  
\hline \hline \end{tabular}
\end{table} 
Table 1: List of collected almond samples analyzed by dual molecular assays. Comparative analysis of cLAMP and qPCR (Cq) results for the detection of _Xf_ in the almond samples used in the study. The Cq values reported are the average obtained by the two laboratories. Cq value > 33 is considered negative. N/A: no absorbance. Successful amplification in cLAMP is indicated with “+”, whereas “\(-\)” indicates a negative result. Small slices (0.2 cm thickness) of cortical tissues (up to 250 mg in total) were cut with a razor blade, disinfected after chopping each sample with diluted commercial bleach (ca. 1% active chlorine), and placed inside a mesh plastic bag (Agdia, Elkhart, IN, USA) in the presence of 1.5 mL sodium chloride-Tris-EDTA extraction buffer (STE 1x), containing also 2% DIECA (diethyldithiocarbamate), 1% PVP-40k (polyvinylpyrrolidone), and Triton 0.1%. Bags were manually crumbled with a hammer to facilitate the breaking of plant tissues and the release of bacterial cells in the extraction buffer [23]. The spilled liquid was recovered in a 1.5 mL centrifuge tube and stored on ice. One hundred \(\upmu\)L of the decanted suspension was retrieved in a new labelled tube, avoiding the plant debris at the bottom. This crude sap aliquot was denatured by a 2 min incubation with an equal volume of 0.4 M NaOH, then subsequently neutralized by mixing for a short time with the same volume of HCl 0.2 M. The neutralized suspension was further diluted to 1:10 in distilled water and finally subjected to the cLAMP assay according to Ref. [24]. Crude sap from healthy almond tissues recovered from greenhouse-grown seedlings, previously tested by qPCR as being _Xf_-free, and nuclease-free water served as negative internal and no-template controls (NIC and NTC), respectively, for each cLAMP round. A standard 30 min incubation was performed at 65 \({}^{\circ}\)C in a portable BIOPIX DNA Technology battery-powered heat block [25]. Moreover, to compare the field-performed cLAMP test, the presence of _Xf_ was then assessed by testing, in duplicate, the same almond crude extracts by qPCR in two different laboratories (IPSP-CNR, Bari and AIT, Vienna) involved with the project, following the TaqMan protocol described by [PERSON] et al., 2010 [26]. One \(\upmu\)L of the alkaline-denatured, neutralized and 1:10 water-diluted sap was added to the cLAMP and qPCR reactions. The primer sequences used in both tests that targeted the _rimM_ gene, highly conserved among all _Xf_ subspecies' genomes and widely validated for _Xf_ detection [17], are reported in Supplementary Table SI.