Update:
Final Progress Report is downloaded in the File (optional) below

View uploaded report

Management of Soybean Root Diseases in Multiple Planting Dates and Environments of North Dakota, 2015 Langdon, Carrington and Minot ND
Venkat Chapara, Michael Wunsch, Amanda Arens, Eric Eriksmoen and Pravin Gautam

The goal of this project is to study the efficacy of seed treatment chemistries to control root disease and their impact on yield in multiple planting dates and environments of North Dakota. Also to improve our understanding of the prevalent root rot pathogens with effective seed treatment options to manage them. Six field experiments were conducted in North Dakota over three locations (Langdon, Carrington and Minot) in 2015 with the funding from North Dakota Soybean Council (NDSC).

Generally, farmers are recommended to plant earlier since the yield potential of soybeans is increased. However, cool and wet soils are frequently encountered at these planting dates and will slow seedling growth making them more vulnerable to seed and root rots caused by plant pathogenic fungi. Eventually resulting in reduced stand. The sensitivity of these pathogens to fungicides used in seed treatment products has been evaluated in this study. Most fungicide seed treatments are active only for 2 to 3 weeks. Thus, when germination and emergence are slowed due to cool soil temperatures, seedlings are still vulnerable to infection by pathogens. This has been the main reason for choosing two different planting dates and the data generated will help to explain why one seed treatment benefits yield at one location and not necessarily at another. Obviously, the choice of a fungicide seed treatment will depend on the knowledge of what disease problems are prevalent in a particular field. Research on knowledge of pathogens is limited on the prevalence of soil borne pathogens that can infect soybean seed and seedlings in ND. Our pathogen isolation results from lab indicated Pythium and Rhizoctonia were the major pathogens in all the three locations we tested.

Products that contain the active ingredients metalaxyl or mefenoxam are effective against Pythium and Phytophthora. Other active ingredients, e.g., azoxystrobin, trifloxystrobin, ipconazole, captan, carboxin, fludioxonil, thiram, sedaxane and thiophanate methyl are effective against Fusarium and Rhizoctonia. Fungicides with straight and combination of above mentioned seed treatment products were selected to manage these seedling rots. The soybean seed (Variety: S007-Y4 for Minot and Langdon; Variety: S04-D3 for Carrington) was treated with straight and combination products. In all 15 chemical treatments and a non-treated control in three locations x two planting dates were planted.

The two year field research objectives have been rigorously tested. Results obtained were compared with the root rot severity to plant stand and yield. No significant differences between the treatments were observed in any location on either plant stand or yield as expected. The benefit of a seed treatment on soybean plantstand establishment was not fully evident. In our 2015 field trials weather has been very co-operative in Langdon and Minot locations. Whereas, in Carrington very low yields were recorded due to dry weather during critical pod-fill period in August, and the field where these trials were located had well-drained soils.