Citation: Hartman, G.L., Bowen, C.R., Haudenshield, J.S., Fox, C.M., Cary, T.R., Diers, B.W. 2015. Evaluation of disease and pest damage on soybean cultivars released from 1923 through 2008 under field conditions in Central Illinois. Agronomy Journal. 107:2373-2380.
Interpretive Summary: Diseases and pests of soybean often reduce soybean yields. Targeted breeding that incorporates known genes for resistance and non-targeted breeding that eliminates susceptible plants in breeding populations reduces the impact of soybean pathogens and pests. Maturity group III soybean cultivars released from 1923 through 2008 were grown in three field environments to determine if disease and insect ratings were associated with year of cultivar release and agronomic characteristics. In 2010, seven of nine traits were negatively correlated to the year of release; newer released cultivars had lower ratings (less disease, insect damage, and better root health) than cultivars with older release dates. In 2011 at two locations, only four out of 13 traits were negatively corrleated to the year of release. The most consistent traits that showed this negative correlation to year of cultivar release were bacterial diseases, brown spot, and root health. This study is of interest to soybean breeders, pathologists, and others that are interested in soybean production and historic evidence of gains in production through breeding.
Technical Abstract: Diseases and pests of soybean often reduce soybean yields. Targeted breeding that incorporates known genes for resistance and non-targeted breeding that eliminates susceptible plants in breeding populations reduces the impact of soybean pathogens and pests. Maturity group III soybean cultivars released from 1923 through 2008 were grown in three field environments to determine if disease and insect ratings were associated with year of release and agronomic characteristics. Disease and pest ratings were made on 40 soybean cultivars at one location (Urbana, Illinois) planted in two rotation treatments in 2010 and on 59 cultivars in two locations (Urbana and Arthur) in 2011. During the season, foliar disease symptoms and insect foliar feeding were recorded. At growth stage R8, plant samples were collected and stem diseases assessed. In at least one environment, foliar incidence reached 100% for bacterial diseases, brown spot, and insect foliar feeding damage and 100% incidence for anthracnose, Cercospora stem blight, and charcoal rot on stems. For severity assessments, seven of nine rating in 2010 had a significant (P < 0.05) negative correlation to year of cultivar release indicating that cultivars more recently released had lower severity ratings than cultivars with older release dates. This study demonstrated that incidence and severity of diseases were less pronounced on more newly-released soybean cultivars, showing that decades of breeding has resulted in increased disease resistance in modern soybean cultivars.