Diseases & Disorders

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2019 Soybean Fungicide Field Trials Summary

This document contains results of soybean field trials conducted during the 2019 growing season to evaluate foliar fungicides to manage various soybean diseases.

corn field with sunrise in the background

2019 Corn Fungicide Field Trials Summary

This document contains results of corn field trials conducted during the 2019 growing season to evaluate foliar fungicides to manage various corn diseases.

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.

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.

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.

Symptoms of three emerging sunflower diseases. From the left: Bacterial Stem Rot, Sclerotinia Basal Rot, and Sunflower Rust.

Bacterial Stem Rot, Sclerotinia Basal Rot and Sunflower Rust Developing in Sunflower

Sunflower scouted this week in Brookings and Kingsbury counties were found with bacterial stem rot, Sclerotinia basal rot and sunflower rust. This area has had plenty of moisture, which favors several diseases to develop in sunflower.

Soybean leaves with small, white lesions with red-to-purple halos throughout.

Frogeye Leaf Spot Developing in Soybeans

Frogeye leaf spot, also known as Cercospora leaf spot, was found in several soybean fields scouted the week of August 19, 2019. Frogeye leaf spot is characterized by irregular to circular lesions, which are tan-to-gray in color with reddish-purplish borders.

A producer loading a planter with fungicide-treated soybean seeds.

Pre-Plant Disease Management Considerations

If the forecast holds true, it looks like it is going to be another year of excessive soil moisture and possible flooding come this spring. The increased level of soil moisture has implications with regards to plant stand establishment as well as root rot and nematode infestations.

Two diseased wheat plants side-by-side. The wheat heads on the left have ergot bodies throughout. The wheat plants on the right are infected with Fusarium head blight.

Assess Your Fields for Ergot and Fusarium Head Blight Before Harvest

The 2019 wheat harvest is well underway in South Dakota, with many acres of winter and much of the spring wheat crop left to harvest. To date, reports on yield and quality have been variable, depending on when the crop was seeded, weather conditions at important growth stages (such as flowering and grain fill) and disease pressure throughout the season.

Collage of four common wheat disease symptoms. From left: Tan spot, strip rust, stagonospora leaf blotch, and bacterial leaf streak.

Winter Wheat Disease Update: Leaf Diseases and FHB on the Increase

Winter wheat fields scouted last week show an increase in fungal leaf diseases and bacterial leaf streak. Among the fungal diseases, the most common leaf diseases are tan spot, Stagonospora leaf blotch, and stripe rust. The risk for Fusarium head blight has also started to increase in a number of areas in the state.