|Cross, Cory -|
|Wrather, Allen -|
|Fothegill, Kent -|
|Shannon, Grover -|
|Shumway, Calvin -|
|Rupe, John -|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 2, 2011
Publication Date: July 11, 2012
Citation: Cross, C., Wrather, A., Fothegill, K., Shannon, G., Li, S., Shumway, C., Rupe, J. 2012. Fungicide, herbicide, and genotype effects on charcoal rot and phomopsis seed decay in soybeans. Plant Disease. 96 (8): 1154-1158. Interpretive Summary: Charcoal rot and Phomopsis seed decay are economically important diseases in soybeans. There are few methods for management of these diseases. The objectives of this study were to evaluate application of the herbicide lactofen, the fungicide azoxystrobin, and soybean lines effects on charcoal rot and Phomopsis seed decay. Results showed that application of lactofen and azoxystrobin had no significant impact on severity of charcoal rot and amount of seed infected with Phomopsis. No soybean cultivar evaluated was resistant to Phomopsis seed decay. However, PI 57562A is more resistant than previously reported charcoal rot resistant line DT97-4290. PI 567562A may be used in breeding programs to further reduce loss to charcoal rot.
Technical Abstract: Yield limiting diseases such as charcoal rot and Phomopsis seed decay have significant impact on the economic potential for soybeans because there are few methods for management of these diseases. The objectives of this study were to evaluate application of the herbicide lactofen, the fungicide azoxystrobin, and soybean genotype effects on charcoal rot and Phomopsis seed decay. Bacterial blight and pod and stem blight also developed during the course of this study, and the effects of treatments on these diseases were evaluated. Application of lactofen at growth stage R1 and azoxystrobin at either planting, R3, or R6 had no significant impact on severity of charcoal rot, percent of harvested seed infected by Phomopsis spp., or severity of pod and stem blight and bacterial blight. No genotype evaluated was resistant to Phomopsis seed decay. Asgrow 4403 was very resistant to bacterial blight, but PI 567562A was very susceptible. Asgrow 4403, DP 5806, and DT 97-4290 were susceptible to pod and stem blight and PI 567562A was resistant. This is the first report of high levels of resistance in PI 567562A to charcoal rot, and resistance in the accession was greater than for DT 97-4290.