Content by Connie Tande

Gibberella ear rot and Fusarium spp. symptoms on two corn ears.

Gibberella and Fusarium Ear Rots Developing in Corn

Corn ear rots are one of the last diseases to scout for in the corn growing season, and sometimes they are ignored or forgotten entirely. Ear rots can cause yield loss in the form of grain quality at harvest, but also cause losses during storage.

A corn field with several plants showing symptoms of stalk rot.

Assess for Corn Stalk Rots

Several corn fields are beginning to show stalk rot and top dieback symptoms. Stalk rots cause the entire plant to die prematurely, which can lead to plants lodging under windy conditions making harvesting problematic.

Two leaves of corn, one showing signs of Southern Rust, the other with Common Rust.

Southern Rust Developing Late in Corn

Southern rust was found in a few corn fields scouted last week. This rust is developing very late in the season and therefore its impact on corn yield will be minimal.

An aerial view of a soybean field with noticable rows of yellowing plants due to SCN infection.

Early Yellowing in a Soybean Field May Indicate Presence of the Soybean Cyst Nematode

Some portions of soybean fields may show clusters of plants yellowing while the rest of the field is still green. One of the factors that could lead to soybean plants showing early yellowing in clusters is soybean cyst nematode (SCN).

Soybean plant with with yellow-chlorotic blotches between leaf veins and noticable browning due to sudden death syndrome.

Sudden Death Syndrome Starting to Develop in Soybeans

Sudden death syndrome of soybean is starting to develop in soybean fields in South Dakota. Fields currently being found with sudden death syndrome have symptomatic plants scattered within the field, but continued disease development may lead to larger clusters of infected plants.

A corn field with several plants displaying long, tan to gray lesions on their leaves.

Goss’s Bacterial Blight Beginning to Show Up in Corn

Goss’s bacterial blight was found in a few corn fields scouted the week of August 5, 2019. The severity ranged from low to moderate, where at least 25 percent of the leaf area was killed by the bacteria infection on several plants. The disease is characterized by long, tan-gray lesions with wavy margins found in the center of the leaf or along the edges of the corn leaf blade.

Two corn diseases displayed side-by-side. The left corn plant has holcus spot lesions on its leaves. The right has paraquat drift injury.

Holcus Spot or Plant Injury?

Is your corn developing spots? Corn fields have been found with what appears to be Holcus spot, a bacterial disease. Upon further investigations, the leaves were found to be negative for any plant pathogens.

A green soybean pod with frogeye leaf spot symptoms. The pod is partially open to reveal developing seed at the end of the pod with frogeye leaf spot symptoms developing.

Frogeye Leaf Spot of Soybean

This fact sheet is about a soybean disease that is increasingly becoming more severe in South Dakota. Moreover, fungicide resistance for this pathogen has been detected in South Dakota.

Left: A close-up of two wheat leaves showing light yellow streaks, a symptom of wheat streak mosaic virus. Right: Winter wheat leaves with small dark brown lesions surrounded by a yellow halo, a symptom of tan spot.

Winter Wheat Disease Update: Wheat Streak Mosaic and Tan Spot Developing at Low Level

Winter wheat fields scouted the week of May 27, 2019 in South Central South Dakota were found with wheat streak mosaic virus and tan spot developing at very low levels. Both diseases were found in non-rotated wheat fields.

Brown roots with white spots on them. The white spots are SCN cysts that contain eggs. Smaller image shows a broken cyst with eggs coming out of it.

Test Your Soil for the Soybean Cyst Nematode (SCN) This Spring

The soybean cyst nematode (SCN) is a major soybean pathogen that causes significant yield loss. Fields that were not tested for SCN last year can still be sampled this spring to determine the presence of SCN or SCN population changes if testing was done in the past.