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Tuesday, October 16, 2001

Barren stalks in corn

Dean Reynolds, Assistant Professor and Extension Plant Pathologist

This summer corn growers in west central and southwestern Minnesota noticed a high percentage of barren stalks and abnormal ear development in some fields. Corn growers and local seedsmen reported 30-40 percent barren stalks in some fields. We surveyed multiple locations for barren stalks in fields along a 50-mile path from Bunde to Madison. The fields surveyed were variety demonstration trials where hybrids from different companies could be compared side-by-side under similar field and environmental conditions. The highest percent of barren stalks observed in the survey was 17 percent; not as high as observed in some commercial fields in the same area. The occurrence of barren stalks was not limited to any particular company's hybrids.

Tuesday, August 7, 2001

When is a Growing Degree Day Not a Growing Degree Day?

D.R. Hicks, Professor of Agronomy and Plant Genetics

Heat accumulation during the growing season can be used as a predictor of plant development. The very high temperatures we've had, especially the high night temperatures, have caused the Growing Degree Day accumulation to be slightly ahead of normal for most of the state. But corn development is still lagging so there is the question of how effective this temperature accumulation really is for corn development.

Monday, June 25, 2001

Soybean and corn diseases

Dean Reynolds, Extension Plant Pathologist

Soybean diseases

The "dreaded" root rots

Fusarium Soybean Rot.jpg
Figure 1. Fusarium root rot on soybeans.
Finally, much of Minnesota is experiencing more than one warm, sunny day in a row. The soybeans, and other crops, were stuck in a slow growth mode for the last month due to the rainy, overcast conditions. But now the crops should start developing more rapidly. Fortunately, Pythium root rot is no longer a concern since it likes cool wet soils and preys on newly germinated soybean seeds and small seedling. However, Fusarium, Phytophthora, and Rhizoctonia root rots are still a threat to soybeans. The warm conditions contributing to the rapid growth of soybeans may actually result in more noticeable root rot symptoms. Now would be a good time to dig seedling in wet, poorly drained areas of fields to look for root lesions caused by the fungal pathogens. Lesions on roots that appear red, reddish brown, or brown are most likely caused by Fusarium or Phytophthora (see Figure 1). Reddish brown lesions that occur on the stem near the ground level are probably caused by Rhizoctonia (see Figure 2). Watch stands in those areas for stand loss. There is not much you can do this year about the diseases. It is probably too late to benefit from a replant if stand loss has occurred. It would be worth while to identify what root rot diseases predominate in your fields and plan for managing them in the future.

Monday, April 30, 2001

Spring planting 2001

D. R. Hicks and S. L. Naeve, Department of Agronomy, University of Minnesota

For the past three years we have had excellent field conditions for early and timely corn and soybean planting in Minnesota. Conditions are such now that this season will be later, but still could be an "average" or "normal" planting season, especially for soybeans. For a reminder of what's normal, the average corn planting date is May 6; it's May 18 for soybeans. If field-drying conditions exist for the next several days, both crops could be planted in the normal timeframe.
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