Diseases

Alfalfa Root Rot

Medicago sativa L.

A complex infection of the alfalfa root system caused by soil-borne pathogens, leading to stand thinning, chlorosis, and root tissue necrosis. The disease is most characteristic of crops in their second or third year of growth.

In the reference 40 varieties crop Alfalfa, where this is mentioned in the description.

The disease is caused by fungi of the genus Fusarium (predominantly F. oxysporum, F. culmorum, F. avenaceum, F. proliferatum), oomycetes of the genera Pythium and Phytophthora medicaginis, as well as Phoma sclerotioides and Paraphoma radicina. The infection is often of a mixed nature, which complicates visual diagnosis.

External symptoms include stunted plant growth, chlorosis, and wilting. Necrotic spots form on the roots, the internal tissues of the root crown show browning of the vascular bundles, and in severe cases, the pith becomes hollow. Under high humidity conditions, a layer of sporulation may appear on the surface of the stems and the root crown.

Alfalfa resistance to root rot is polygenic in nature and is associated with transcription factors of the bHLH, SBP, AP2, WRKY, and MYB families. Breeding efforts are focused on broad-spectrum resistance, as specific R-genes are rarely identified in cultivar pedigrees, and assessment is conducted based on the results of phytopathological testing.

General information about the subject — on the page Root rots.

Sources8

Varieties of Alfalfa mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.