Soybean School: Identifying seedling diseases


Soybeans don’t like wet feet, and when rain is plentiful in June and July, saturated soils typically lead to an increase in fungal seedling diseases.

Four of the most common culprits are pythium and phytophthora root rots as well as rhizoctonia and fusarium. On this episode of the RealAgriculture Soybean School, Ontario Ministry of Agriculture, Food and Rural Affairs pathologist Albert Tenuta looks at how to identify these diseases and what growers can do to help defend their crops.

Tenuta says pythium and phytophthora are more common in heavier clay soils prone to saturation. They produce a wet rot, while rhizoctonia and fusarium fungal pathogens tend to produce a dry, leathery rot.

“With rhizoctonia we start seeing red lesions and cankers at the stem line,” notes Tenuta. “With fusarium we get brown discolouration, we can get vascular discolouration and when you cut those tap roots you’ll see that fungal infection or browning inside there as well.

“Just by digging them up you can really get it down to fusarium, rhizoc, phytophthora or pythium just by how they disintegrate in your hand.” he adds.

In the video below, recorded at Southwest Crop Diagnostic Days at the University of Guelph’s Ridgetown campus, Tenuta highlights how different crop rotations can help or hinder disease development. He also discusses the key role nitrogen plays in establishing strong root systems and how variety choice and seed treatments can help protect the crop from these diseases.

Tap here for more Soybean School videos.

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