Also, samples have been submitted to the Plant Disease and Diagnostic Clinic that has tested positive for Phytophthora, Fusarium spp, and Rhizoctonia.
Similar to what we emphasized earlier this year, when we recommended assessing plants from the V2 to V4 growth states to look for early indications of stressed soybean plants, follow up assessments beginning now during the reproductive period is important for understanding the possible complex set of interactions. Start by checking areas of the field where there may be higher compaction, such as the headlands. In 2008, we saw a variety of symptoms in the field. Check soybean plants for petiole retention; also scrape away at the epidermis to look for signs of organsims like Macrophomina phaseolina; lastly, split and examine stems and determine if there are necrotic areas to the stem or as we move into the later reproductive period, brown stem rot. Based on our observations from 2008, there is not a single pattern to these composite sets of symptoms in field as we saw anything from circular-like patches to patterns that followed down the rows.
If you have suspected samples, submit those to the Plant Disease and Diagnostic Clinic. For further information about the different soybean diseases that may be found in Wisconsin, consult Soyhealth.
