Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVED RESISTANCE TO SOYBEAN PATHOGENS AND PESTS

Location: Soybean/maize Germplasm, Pathology, and Genetics Research

Title: Effect of fungicide application and cultivar on soybean green stem disorder

Authors
item Hill, Curtis -
item Bowen, Charles
item Hartman, Glen

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 27, 2013
Publication Date: September 1, 2013
Citation: Hill, C.B., Bowen, C.R., Hartman, G.L. 2013. Effect of fungicide application and cultivar on soybean green stem disorder. Plant Disease. 97:1212-1220.

Interpretive Summary: Green stem disorder of soybean has increasingly become a nuisance for soybean producers because of the increased difficulty for the combine to cut through areas of a field where plants with this condition are prevalent. Soybean producers must adjust combine controls to optimize harvest including reducing ground speed while increasing engine power to avoid blocking the opening between the concave and cylinder with moist plant material. The disorder is distinguished from other manifestations of delayed plant maturity by the delayed senescence only of stems with normal pod ripening and seed maturation. The main objectives of this study were to compare the effects of fungicides with different chemistries and timing of fungicide application on incidence of green stem disorder using green stem disorder sensitive and insensitive soybean cultivars. Species of Diaporthe/Phomopsis and Macrophomina phaseolina were more frequent in stems without the disorder, whereas species of Colletotrichum were found mostly in stems with the disorder. Headline generally had a stronger effect than Domark in increasing incidence of the disorder, especially in green stem disorder sensitive cultivars, with over 50% incidence in many cases. Overall, the mid-season fungicide applications of Headline and a Domark-Headline mixture produced higher incidence of green stem disorder than early or late-season applications. From the results of this study, soybean producers should be aware of the possible risk that fungicide application may have in increasing incidence of green stem disorder. In addition, producers can help manage green stem disorder by selecting soybean cultivars reported to be consistently insensitive to the disorder. This information is important to crop consultants, soybean growers, and others interested in soybean productivity under field condidtions.

Technical Abstract: Green stem disorder of soybean [Glycine max (L.) Merr.] has increasingly become a nuisance for soybean producers. The disorder is distinguished from other manifestations of delayed plant maturity by the delayed senescence only of stems with normal pod ripening and seed maturation. The main objectives of this study were to compare the effects of fungicides with different chemistries and timing of fungicide application on incidence of green stem disorder using green stem disorder sensitive and insensitive soybean cultivars. Species of Diaporthe/Phomopsis and Macrophomina phaseolina were more frequent in stems without the disorder, whereas species of Colletotrichum were found mostly in stems with the disorder. Headline generally had a stronger effect than Domark in increasing incidence of the disorder, especially in green stem disorder sensitive cultivars, with over 50% incidence in many cases. Overall, the mid-season fungicide applications of Headline and a Domark-Headline mixture produced higher incidence of green stem disorder than early or late-season applications. Significant (P < 0.01) location x cultivar interaction occurred in all field experiments. Higher percent green stem disorder and higher yields were significant (P < 0.05), had positive regression slopes in 11 of the 28 trials, and was depended on soybean cultivar and location. From the results of this study, soybean producers should be aware of the possible risk that fungicide application may have in increasing incidence of green stem disorder. In addition, producers can help manage green stem disorder by selecting soybean cultivars reported to be consistently insensitive to the disorder.

Last Modified: 11/27/2014
Footer Content Back to Top of Page