Phialophora stem rot

Phialophora gregata (also known as Cadophora gregata) is a fungal pathogen responsible for brown stem rot in soybean crops. It belongs to the kingdom Fungi and is categorized as a vascular pathogen that systemically infects the plant host, causing significant disruption to water transport.

The primary symptom of this disease is the browning of the pith and vascular tissues within the soybean stem. While internal symptoms are visible early, external signs like interveinal chlorosis and necrosis typically appear during the seed-filling stage, eventually leading to premature senescence and yield loss.

The biology of the pathogen centers on its ability to survive as mycelium in infected crop residues. It is a soil-borne fungus that initiates infection through the roots. The fungus produces conidia, which facilitate the systemic movement of the pathogen through the xylem vessels of the infected plant.

The development of the disease is highly dependent on environmental factors, specifically cool and moist soil conditions during the early growth stages of soybeans. If these conditions persist, the colonization of the stem tissue is accelerated, leading to severe outbreaks across agricultural fields.

Control strategies for Phialophora gregata focus on cultural practices, primarily the implementation of a 3-year crop rotation to break the infection cycle. Resistant soybean varieties are the most effective tool for management. Additionally, farmers should ensure proper tillage to facilitate the decomposition of crop residues and apply systemic seed treatments to reduce initial infection pressure.

• Crop rotation cycles
• Planting resistant cultivars
• Tillage practices
• Seed treatment fungicides
• Sanitation of crop fields