Damping-off of seedlings

Damping-off of seedlings, specifically caused by Aphanomyces cochlioides, is a severe soil-borne disease that significantly impacts young plants. This pathogen, an oomycete, thrives in moist soil conditions and is capable of causing rapid decay of seedlings before they emerge or shortly after emergence, leading to significant stand losses.

This disease primarily infects crops within the Amaranthaceae family, with fodder beet (mangels) and sugar beets being the most susceptible. The fungus attacks the underground parts of the plant, disrupting the transport of nutrients and water from the root system to the stems and leaves, which is fatal for early-stage crops.

Common symptoms include water-soaked lesions that appear on the hypocotyl and the root, which later turn brown or black. The affected tissues become soft and necrotic, causing the seedling to wilt, collapse, and die. If the infection occurs at a slightly later stage, plants may survive but will remain severely stunted with poorly developed root systems that are blackened and brittle.

The development and spread of Aphanomyces cochlioides are heavily dependent on environmental factors. Excessive soil moisture, poor drainage, and soil compaction are the primary drivers for disease outbreaks. The pathogen produces motile zoospores that swim through water films in the soil to reach the host roots, making waterlogged fields particularly vulnerable to severe infection.

Control strategies for this disease focus on integrated management. Key preventive measures include:

• using high-quality fungicide-treated seeds;
• implementing proper crop rotation to reduce inoculum buildup;
• improving soil drainage and structure;
• maintaining soil pH through liming, as the pathogen is often less aggressive in slightly alkaline environments.