Tomato spotted wilt virus (TSWV) and late leaf spot (LLS), caused by Cercosporidium personatum, are important diseases affecting peanuts (Arachis hypogaea L.). One of the most promising ways to combat these diseases is with resistant cultivars created through the development of recombinant inbred lines allowing for the discovery of resistance genes. These mapping populations can be very large making phenotyping time consuming and difficult; the objectives of this research aim to increase the efficiency of phenotyping methods. Field experiments were conducted to compare genotypes from multiple mapping populations for resistance to the two diseases as well as evaluate the use of unmanned aerial systems (UASs) and their ability to increase efficiency when phenotyping TSWV and LLS. Juvenile plants were also evaluated for resistance to LLS. Results indicated that some populations showed more resistance to disease than other and UASs proved to be helpful in the phenotyping of mapping populations. Parental lines evaluated were also susceptible to infection by C. personatum at a very early age.