Source: Dr. Anne Dorrance, OSU
Low stands or poor development of plants is, unfortunately, a common occurrence for fields that were planted in many regions of Ohio with heavy soil or are poorly drained soil. Symptoms include skips, missing plants, or dried up and brown seedlings. There may also be, wilting plants with and rotten, brown, decaying spots or lesions on the roots. Now is an excellent time to scout stands and check to be sure that the fields are not just crusted over – and that the seeds and seedlings that are there are still healthy.
While there, dig up a few of the affected plants, if the roots are brown and soft, the seedling will die eventually or be very weak. So don’t count them as part of your total stand. On soybeans check to see if there are nodules, the corky looking knobs on the roots that help legumes fix nitrogen. The cold, wet weather does not favor nodulation, so this may take a bit longer, for now, native Rhizobium spp. to get a foothold in the plants. Once the plants have nodules, they will recover and grow. On corn, the root (mesocotyl) between the young seedling and the seed, should be white. If it is dark brown or soft, this will also be a weakened plant. Some pathogens, if the environment is right, will continue to multiply and grow to kill the seedling.
For management, improving soil drainage, and having at least two ingredients in the seed treatment mixture targeting water molds (Pythium and Phytophthora) are necessary for the challenging areas in Ohio that have a history of replanting. If you do have to replant, take a look at what the seed treatment package is and note what is in the mix. The one caution, though, is if the field was submerged for more than 24-48 hours (Ponding), this is flood injury, and there are no seed treatments for this.