The main leaf spot diseases early leaf spot (ELS) and late leaf spot (LLS), caused by Passalora arachidicola (Hori) and Nothopassalora personata (Berk & M.A. Curtis), respectively, cause great yield loss when not effectively managed. Planting resistant varieties together with other practices is the most economical and practical way to manage these diseases. The main goals of this study were to identify wild-derived sources and to determine alleles for ELS and LLS resistance. Thirteen induced allotetraploids were evaluated using a detached leaf bioassay to identify genotypes that can be used in breeding programs. Induced allotetraploids exhibited fewer and smaller lesions with limited sporulation and reductions in disease progression. Also, this study successfully combined Arachis cardenasii-derived segments with varying leaf spot resistance mechanisms. Two regions were found to have significant effects on ELS development, the long segment on top of chromosome A02 and the segment on chromosome A09 reduced lesion size. The segment on top of chromosome A02 (short or long) and the segment on the lower end of chromosome A03 reduced LLS development both in the bioassay and field. Although not the focus, the effects of the segments on rust were also evaluated: the long segment on chromosome A02 reduced the production of pustules while the segment on chromosome A09 lowered the rust susceptibility index and AUDPC. However, the segment on the lower end of A03 had the most significant effects on reducing rust. This study also assembled a reference genome for N. personata that has a total size of 56.3 Mb with N50 of 1.5 Mb, maximum contig length of 3.9 Mb, and 99.3% BUSCO. This research will contribute to the development of peanut cultivars with resistance to ELS and LLS that could reduce fungicide applications and the high-quality genome can be used as a reference to align sequences from other isolates for population biology studies. This information can be used to develop a sustainable disease resistance breeding program and devise the best disease management strategies.