Soybean stand evaluation

first_imgShare Facebook Twitter Google + LinkedIn Pinterest As soybeans are emerging it is important to take some time to evaluate the stands.“Most are reporting good stands,” said Laura Lindsey, with OSU Extension. “Keep in mind that soybean stands may look a little uneven especially in areas of Ohio that are dry. If there are gaps where soybeans have not yet emerged, dig around in the area where there are no plants. If the seed is healthy and germinated, but just not broken through, with moisture, the soybeans should continue to emerge.”To get a handle on the stand, Lindsey recommends the following method: count the number of plants in 69 feet 8 inches of row for 7.5 inch-row spacing, 34 feet 10 inches for 15-inch row spacing, or 17 feet 5 inches of row for 30-inch row spacing. These counts represent 1/1000th of an acre (i.e., 120 plants in 69 feet 8 inches of row in 7.5-inch row spacing = 120,000 plants per acre).In areas where stands are less than ideal, there could be a number of different disease problems that could be to blame. OSU Extension plant pathologist Anne Dorrance has been hearing about some emergence problems due to diseases.“The most common symptom is spotty areas around the field with large skips or limited emergence,” Dorrance said. “Take a garden trowel and dig up a few places and try to find the seed that was placed there.”Here is a review from Dorrance of the seedling disease issues that are common most years in Ohio.1. The Watermolds, Pythium and Phytophthora, are very common on poorly drained, high clay soils. These pathogens love wet soil conditions. The few places in the state where saturated soil conditions have occurred are the very typical areas for these problems. Look for any shade of brown or tan on the seedling root or hypocotyl — the area right behind the deep green cotyledon.2. Rhizoctonia is another foe of seedlings. Fluctuating conditions, dry to wet can sometimes favor this pathogen. This is a brick corky red color, close to a brick house color, on the lower stem and the roots that can range from light brown to dark brown in color.3. Fusarium graminearum or other Fusarium spp. — Fusarium tends to be bright pinkish-red and fluffy. We have found this most often in fields with a high level of corn residue.There are other pests that will feed on the seeds and seedlings.  Seed corn maggot is one potential problems and slug damage is another. In these cases, missing plants or plants with holes in leaves or cotyledons will appear differently than the sunken, rotting tissue of diseases.last_img

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