A total of 304 Wickham germplasms of Hevea brasiliensis were used as materials to systematically investigate the genetic diversity of botanical traits, leaf phenological dynamics in winter and spring, and powdery mildew disease grades, and cluster analysis was conducted. This study aimed to screen elite germplasms with resistance or escape to powdery mildew, thereby providing theoretical basis and material support for disease-resistant breeding of H. brasiliensis. The results showed that the genetic diversity indices of 33 botanical traits ranged from 0.225 to 1.401, and the Shannon-Wiener diversity indices of 12 quantitative leaf morphological traits varied from 1.657 to 2.218. The genetic diversity of quantitative traits was markedly higher than that of qualitative traits. The genetic diversity index of leaf phenology in winter and spring ranged from 0.851 to 1.697, reaching the highest on February 9 and February 22, and the lowest on April 3. The genetic diversity index of powdery mildew disease grade varied between 0.878 and 1.366, with the highest diversity observed on March 20, when 99% of the germplasm accessions were infected by powdery mildew. Correlation analysis between phenological traits and powdery mildew disease grade indicated that the copper-red to discoloration transition stage and the discoloration stage of leaves on March 5 were the critical susceptible periods. Leaf maturity showed a significantly strong negative correlation with powdery mildew disease grade at this stage (r=?0.48). It is recommended to regard this period as a crucial window for the prevention and control of powdery mildew. Based on phenological dynamics and powdery mildew grades, the 304 germplasms were divided into six clusters via cluster analysis. Among them, Cluster Ⅲ was characterized by early leaf abscission, while Cluster Ⅵ showed the latest leaf defoliation, both with relatively low disease grades. Combined with the growth dynamics of leaf phenological stages and the occurrence of rubber powdery mildew, five germplasm accessions including No. 21, No. 152, No. 166, No. 222 and No. 290 were screened out with the mildest disease susceptibility. This study clarified the phenotypic diversity of Wickham germplasms in H. brasiliensis and the correlation rules between phenology and powdery mildew occurrence, and identified superior disease-resistant and disease-escaping materials, which can provide important references for powdery mildew resistance breeding of H. brasiliensis.