Leaf Samples
To study the structure and diverse differences of the phyllosphere microbial communities of rubber trees with powdery mildew in different regions of Hainan, four representative rubber plantation farms were selected as sampling sites, namely, Baisha (BS), Danzhou (DZ), Wanning (WN), and Wuzhishan (WZS). For each plantation, leaf samples were collected in April 2021 (during the phenological stage when leaves appeared pale green) from infected rubber trees (diameter at breast height: 25–35 cm) diagnosed with a Level 3 powdery mildew infection (i.e., white spots covering more than 33% of the leaf area of the tree) (Qin et al., 2015).
The five-point sampling method—i.e., the diagonal line’s midpoint was first set as the central sampling point, then four equi-spaced additional points along it were set—was applied to collect samples from each rubber farm, using three trees per point, with four leaves from each tree placed in one sterile bag as a sample. Three replications were set and marked as _1, _2 and _3. Uninfected leaves of the same size (at Level 0) were collected from non-infected healthy trees using the same method to serve as a blank control (denoted as _CK).
The sample number, time, and place of collection, in addition to the latitude, longitude, altitude, and ambient temperature and humidity on the day of leaf sampling were recorded (Table S1).