''Clavibacter insidiosus'' is a species of ''

Clavibacter ''Clavibacter'' is a genus of aerobic Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories a ...

''. It causes bacterial wilt, with its most notable host being ''Medicago sativa'' (

alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as w ...

). Other species in the ''

Medicago ''Medicago'' is a genus of flowering plants, commonly known as medick or burclover, in the legume family (Fabaceae). It contains at least 87 species and is distributed mainly around the Mediterranean basin. The best-known member of the genus is ...

'' genus are also known to be hosts such as ''

Medicago falcata ''Medicago falcata'' is a plant species of the genus '' Medicago''. It is native to much of Europe and Asia, but is found throughout the world. It forms a symbiotic relationship with the bacterium ''Sinorhizobium meliloti'', which is capable of ...

''. Additionally, ''

Lotus corniculatus ''Lotus corniculatus'' is a flowering plant in the pea family Fabaceae, native to grasslands in temperate Eurasia and North Africa. Common names include common bird's-foot trefoil, eggs and bacon, birdsfoot deervetch, and just bird's-foot trefoi ...

, Melilotus alba,

Onobrychis viciifolia ''Onobrychis viciifolia'', also known as ''O. sativa'' or common sainfoin () has been an important forage legume in temperate regions until the 1950s. During the Green Revolution it was replaced by high yielding alfalfa and clover species. Due t ...

'', and ''

Trifolium Clover or trefoil are common names for plants of the genus ''Trifolium'' (from Latin ''tres'' 'three' + ''folium'' 'leaf'), consisting of about 300 species of flowering plants in the legume or pea family Fabaceae originating in Europe. The genus h ...

'' sp. are known hosts.

Pathology

Plants like alfalfa are often mowed, and this causes cut stems. The cut stems increase disease susceptibility be providing wounds for the bacteria to enter.Rhodes, Landon H, and William O. Lamp. “Bacterial Wilt” ''Compendium of Alfalfa Diseases and Pests'', by Deborah A. Samac, third ed., American Phytopathological Society, 2015, pp. 62–63. ''C. insidiosus'' causes a systemic disease: the leaflets curl up, an indicative symptom of this disease. Occasionally, it causes necrosis of the leaflets. Yellowing of the plant and yellow-brown roots often occurs. This disease is either fatal or causes severe damage to the host with the bacteria leading to stunted growth. ''C. insidiosus'' needs to be cultured from the infected plant tissues and PCR-tests must be run to confirm a diagnosis. ''Clavibacter insidiosus'' is typically dispersed by the moving of hay between different agricultural sites. Farm equipment that is not properly sanitized can also spread the pathogen. Water is known to move the bacterium; if an area in not irrigated and there is low rainfall, the disease will usually not be present. Plant wounds, specifically on the stem or roots, increase disease susceptibility (because there is now wound for the bacteria to enter) and are often made by mowing, nematodes, or insects. Stem nematodes often act as a vector. They can carry the bacteria on their surface. If the plant is infected by root-knot nematodes, bacterial wilt is more likely and typically more severe. Infested soil can additionally cause disease. A small number of diseased plants (about 6.3-7.7%) can transmit the bacterium to their seeds.

References

{{Taxonbar, from=Q62855919 Microbacteriaceae Bacterial plant pathogens and diseases