Acrocalymma root and crown rot

The disease is caused by the fungus Acrocalymma medicaginis, which is recognized as a significant pathogen affecting the root and crown tissues of alfalfa (Medicago sativa). This pathogen is particularly destructive as it targets the plant's essential structural base, hindering its long-term viability in forage fields.

The primary symptoms include the discoloration and necrosis of the crown and upper root system. Affected plants exhibit a brown or black rot that compromises the vascular integrity of the plant, often leading to stunted growth, yellowing of foliage, and eventually the death of the entire plant.

Development and spread of the pathogen are highly favored by wet, waterlogged soil conditions and moderate temperatures. The fungus persists in the soil and on crop debris, making it a persistent challenge in fields where alfalfa is cultivated continuously without adequate breaks or proper soil drainage management.

The economic impact of this rot is substantial, as it leads to thinning stands and reduced yield quality. As the crowns are destroyed, the plant loses its ability to regenerate after cutting, which necessitates more frequent field renovation and results in significant losses for forage producers.

• Implement a long-term crop rotation cycle to reduce soil-borne inoculum.
• Select alfalfa varieties with documented resistance to root rot diseases.
• Ensure excellent field drainage to minimize saturated soil conditions.
• Manage soil pests that create entry points for fungal pathogens in roots.
• Apply balanced fertilization to support strong root growth and plant vigor.