Based on fungicide efficacy studies conducted by Mississippi State University in 2016, Tom Allen, Mississippi State Extension plant pathologist, noted the impact of treatments on multiple diseases, including target spot.
Efficacy varied depending on the severity of diseases such as frogeye leaf spot and Septoria brown spot. But the defoliation caused by target spot in spite of fungicide treatment prompted Allen to develop a list of things to keep in mind for managing target spot during 2017:
- In general, soybean target spot commonly occurs in the lower canopy.
- Environment is the most important aspect as to whether or not target spot will occur to the same degree in 2017.
- Although environment is the main ingredient for disease to occur, some soybean varieties are extremely susceptible to target spot.
- Spraying a fungicide automatically and not observing target spot after the application does not mean the fungicide controlled the disease.
- A mixed mode of action fungicide application may be more beneficial for 2017 and beyond.
- Soybean foliar diseases occur as a complex, and rarely is only disease the target of a fungicide application.
For more details on the university’s efficacy studies, check out Allen’s report here.