Content by Connie Strunk

Three corn cobs with common ear rots. From left: Fusarium ear rot, Gibberella ear and Diplodia ear rot.

Scout for Corn Ear Rots

Several corn fields scouted in northeastern South Dakota counties were found with ear rots. Ear rots were mostly prevalent in areas that experienced hailstorms in the recent past. Ear rots in corn are caused by a few fungal pathogens, and which ear rot develops depends on the weather conditions.

A portion of a soybean field with soybean plants maturing with the soybean leaves turning yellow with the leaves and stems drying down. The plants in the middle of the picture were also found with charcoal rot.

Charcoal and Fusarium Rots Observed in Early Senescing Soybean Plants

The drought conditions in South Dakota have led to early soybean senescence in some areas. However, some of the early senescing may be due to dry-season diseases, such as charcoal and Fusarium rots.

A wheat field that is bright yellow due to infection of Wheat streak mosaic virus.

Pre-Plant Wheat Streak Mosaic Disease Management Strategies

Drought conditions tend to promote high wheat curl mite populations. Wheat streak mosaic virus and other viruses transmitted by wheat curl mites are best managed through cultural practices performed before planting.

Oat leaf with very low crown rust.

Crown Rust of Oats

Fact sheet on Crown Rust of Oats for agronomist and growers.

Tan-gray Goss’s bacterial blight lesions were observed in scouted corn fields.

Goss's Bacterial Wilt and Leaf Blight of Corn

Fact sheet for identifying Goss’s bacterial wilt and leaf blight of corn, also known
as bacterial leaf freckles and wilt.

Young farmer examining soybean plants n a field at sunset.

Be Aware of Fungicide Resistance in Field Crops

A few soybean and corn fields have received or will be receiving a fungicide application this season. We recommend scouting fields treated with fungicides to determine if diseases are controlled as expected or if there are signs of reduced sensitivity.

A soybean plant with wilting leaves due to stem canker surrounded by healthy soybean plants.

Stem Canker Developing in Some Soybean Fields

A few soybean fields are showing some wilting plants due to stem canker. The field entries and head rows are the most-impacted parts of these fields. The current dry conditions are stressing the plants and causing early development of the disease.

Green soybeans with yellowing throughout.

Bacterial Blight Developing In Some Soybean Fields

Bacterial blight was found developing in a few soybean fields scouted the week of July 19. Leaf tattering is a common symptom of bacterial blight and happens when expanding bacterial blight lesions coalesce and form large brown patches.

Three bean leaf beetles. From Left: Brown beetle with black spots on a green leaf. Yellow beetle with black spots on a green leaf. Red beetle with black spots on a green leaf.

Monitor Soybean for Bean Leaf Beetle Activity

Some of the bean leaf beetles we are currently observing in South Dakota may make up the population of overwintering adults. While these adults are in soybean, they can cause significant amounts of defoliation to the leaves.

Three soybean fields with yellowing issues due to potassium deficiency, iron deficiency chlorosis and soybean cyst nematode.

What Is Causing Soybeans to Yellow at This Time?

Recently scouted soybean fields were observed with yellowing plants, and one field was found to have plants dying prematurely. Learn some of the factors that may cause soybean plants to yellow at this time in the growing season.