A logistic regression model was used to perform association tests between SNPs and disease scores. Population stratification was controlled using the first 20 ancestry principal components (PC’s) as covariates in the logistic model. GWAS was performed using the PLINK 1.9 package (, https://www.cog-genomics.org/plink2, ) and 3220 SNPs on 327 independent individuals (172 cases and 155 controls, all pairwise IBS < 0.185). Prior to association testing, individuals with missing genotype rate > 10% were deleted, leaving effectively 172 cases (susceptible or diseased trees) and 155 controls (resistant or symptom-free trees). SNPs were then filtered for Hardy-Weinberg equilibrium (p-values >10−5), minor allele frequencies (MAF > 0.05) and missing genotypes across individuals (< 10%). In total, 3155 SNPs were included in the association test after filtering. The genotyping rate was equal to 0.99. For every SNP included in the case-control test, the exact P value [P] and the estimated odds ratio [OD] for the association between the minor allele [A1] and the disease phenotype were calculated. Resulting p-values underwent genomic inflation control.