''Cercospora beticola'' is a

fungal A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

plant pathogen which typically infects plants of the genus ''

Beta Beta (, ; uppercase , lowercase , or cursive ; grc, βῆτα, bē̂ta or ell, βήτα, víta) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Modern Greek, it represents the voiced labiod ...

'', within the family of Chenopodiaceae. It is the cause of Cercospora leaf spot disease in sugar beets, spinach and swiss chard. Of these hosts, Cercospora leaf spot is the most economically impactful in sugar beets (''Beta vulgaris)''. ''Cercospora beticola'' is a deuteromycete fungus that reproduces using conidia. There is no teleomorph stage. ''C. beticola'' is a necrotrophic fungus that uses phytotoxins specifically ''Cercospora beticola'' toxin (CBT) to kill infected plants. CBT causes the leaf spot symptom and prevents root formation. Yield losses from Cercospora leaf spot are around 20 percent.

Hosts and symptoms

Hosts of ''Cercospora beticola'' include sugar beets (''

Beta vulgaris ''Beta vulgaris'' (beet) is a species of flowering plant in the subfamily Betoideae of the family Amaranthaceae. Economically, it is the most important crop of the large order Caryophyllales. It has several cultivar groups: the sugar beet, of gre ...

''), swiss chard (''Beta vulgaris'' L. subsp. ''cicla)'' and other leafy greens. Symptoms include the random distribution of spots with brownish red rings which eventually cause leaf collapse. Older leaves will have spots of larger diameters as rings grow outward. Conidia are not observable by the unaided eye

Disease cycle

Stromata (a sclerotia-like survival structure containing conidia when made) in field debris starts the life cycle. Under favorable wet conditions, conidia are rain-splashed and insect-carried to new hosts, where, under humid and wet conditions, they germinate and penetrate through stomata. These conidia germinate in polycyclic microcycles until the end of the growing season. At the end of the growing season, ''C. beticola'' produces stromata again as a survival structure. Microcycles like the one used by ''C. beticola'' are very effective at producing many conidia. Because these conidia are effective at penetrating the host, mycelium is not necessary, and conidia produce their own conidia at each new infection (microcycle). There have been no direct observations of sexual spores in C. beticola.

Management

Copper was historically used to control ''C. beticola'' in the field, though today fungicides are more common. ''C. beticola'' has been shown to have some resistance to benzimidazole and thiophanate class fungicides. As a result, experts often have recommended fungicide rotation to kill any potential fungicide resistant strains. Some varieties of sugar beet also show resistance to ''C. beticola'', unfortunately they have all had low yields in lab tests. Today the most common fungicides used are QoI, Headline, Proline, Inspire SB, Eminent and Super Tin or Agri Tin

Gallery

File:Spinach- Cercospora leaf spot - 3.jpg, Spots on a spinach leaf caused by ''Cercospora beticola'' File:Spinach- Cercospora leaf spot - 8.jpg, Close-up of a spot on a spinach leaf caused by ''Cercospora beticola''

References

{{Taxonbar, from=Q2070817 beticola Fungal plant pathogens and diseases Eudicot diseases