Fusarium is a large genus of filamentous fungi widely distributed in soil and in association with plants. Most species are harmless saprobes, and are relatively abundant members of the soil microbial community. Some species produce mycotoxins in cereal crops that can affect human and animal health if they enter the food chain. The main toxins produced by these Fusarium species are fumonisins and trichothecenes.
The name of Fusarium comes from Latin fusus, meaning a spindle.
The taxonomy of the genus is complex. A number of different schemes have been used, and up to 1,000 species have been identified at times, with approaches varying between wide and narrow concepts of speciation ('lumpers' and 'splitters').
Sections previously described include;
Selected species include;
- F. avenaceum
- F. bubigeum
- F. culmorum
- F. graminearum
- F. langsethiae
- F. oxysporum
- F. poae
- F. sporotrichioides
- F. tricinctum
- F. verticillioides
- F. virguliforme
The name of Fusarium comes from Latin fusus, meaning a spindle.
The genus includes a number of economically important plant pathogenic species.
Fusarium graminearum commonly infects barley if there is rain late in the season. It is of economic impact to the malting and brewing industries, as well as feed barley. Fusarium contamination in barley can result in head blight, and in extreme contaminations, the barley can appear pink. The genome of this wheat and maize pathogen has been sequenced. F. graminearum can also cause root rot and seedling blight. The total losses in the US of barley and wheat crops between 1991 and 1996 have been estimated at $3 billion.
Fusarium oxysporum f.sp. cubense is a fungal plant pathogen that causes Panama disease of banana (Musa spp.), also known as fusarium wilt of banana. Panama disease affects a wide range of banana cultivars, which are propagated asexually from offshoots and therefore have very little genetic diversity. Panama disease is one of the most destructive plant diseases of modern times, and caused the commercial disappearance of the once dominant Gros Michel cultivar. A more recent strain also affects the Cavendish cultivars used as a substitute for Gros Michel. It is considered inevitable that this susceptibility will spread globally and commercially wipe out the Cavendish cultivar, for which there are currently no acceptable replacements.
Some species may cause a range of opportunistic infections in humans. In humans with normal immune systems, fusarial infections may occur in the nails (onychomycosis) and in the cornea (keratomycosis or mycotic keratitis). In humans whose immune systems are weakened in a particular way, (neutropenia, i.e., very low neutrophils count), aggressive fusarial infections penetrating the entire body and bloodstream (disseminated infections) may be caused by members of the Fusarium solani complex, Fusarium oxysporum, Fusarium verticillioides, Fusarium proliferatum and, rarely, other fusarial species.
Use as human food
Some consumers of fusarium products have shown food allergies similar in nature to peanut and other food allergies. People with known sensitivities to molds should exercise caution when consuming such products. 
Mass casualties occurred in the Soviet Union in the 1930s and 1940s when Fusarium-contaminated wheat flour was baked into bread, causing alimentary toxic aleukia with a 60% mortality rate. Symptoms began with abdominal pain, diarrhea, vomiting, and prostration, and within days, fever, chills, myalgias and bone marrow depression with granulocytopenia and secondary sepsis occurred. Further symptoms included pharyngeal or laryngeal ulceration and diffuse bleeding into the skin (petechiae and ecchymoses), melena, bloody diarrhea, hematuria, hematemesis, epistaxis, vaginal bleeding, pancytopenia and gastrointestinal ulceration. Fusarium sporotrichoides contamination was found in affected grain in 1932, spurring research for medical purposes and for use in biological warfare. The active ingredient was found to be trichothecene T-2 mycotoxin, and it was produced in quantity and weaponized prior to the passage of the Biological Weapons Convention in 1972. The Soviets were accused of using the agent, dubbed "yellow rain", to cause 6,300 deaths in Laos, Kampuchea, and Afghanistan between 1975 and 1981. The "biological warfare agent" was later purported to be merely bee feces, but the issue remains disputed.
Following an outbreak of Fusarium oxysporum that affected coca plantations in Peru, and other crops planted in the area, the United States has proposed the use of the agent as a mycoherbicide in drug eradication. In 2000, a proposal was passed to use the agent as part of Plan Colombia. In response to concerns use of the fungus could be perceived as biological warfare, the Clinton Administration "waived" this use of Fusarium. A subsequent law passed in 2006 has mandated the testing of mycoherbicide agents - either Fusarium oxysporum or Crivellia papaveracea - in field trials in U.S. territory. Use of Fusarium oxysporum for these tests has raised concerns because resistant coca from the previous outbreak has been widely cultivated, and the fungus has been implicated in the birth of 31 anencephalic children in the Rio Grande region of Texas in 1991, the loss of palm trees in Los Angeles, and eye infections from contact lens solutions. The alternative Crivellia papaveracea is less well known; despite decades of study in the Soviet biowarfare lab in Tashkent, Uzbekistan, the relevant mycotoxins reportedly have not yet been isolated, named, or studied.
- Nelson 1994.
- Moretti 2009.
- Watanabe 2011.
- Brewing Microbiology, 3rd edition. Priest and Campbell, ISBN 0-306-47288-0
- Walsh TJ, Dixon DM (1996). Spectrum of Mycoses. In: Baron's Medical Microbiology (Baron S et al., eds.) (4th ed.). Univ of Texas Medical Branch. ISBN 0-9631172-1-1. (via NCBI Bookshelf).
- Howard DH (2003). Pathogenic Fungi in Humans and Animals (2nd ed.). Marcel Dekker. ISBN 0-8247-0683-8. (via Google Books).
- Katona, S. J.; E. R. (November 2002). "Sensitivity to Quorn mycoprotein (Fusarium venenatum) in a mould allergic patient". J Clin Pathol 55 (11): 876–7.
- World Health Organization (1999-09-01). "Toxic effects of mycotoxins in humans". Retrieved 2007-05-27.
- Drug Policy Alliance (2006). "Repeating mistakes of the past: another mycoherbicide research bill". Retrieved 2007-05-27.
- Earl C (1984). "Yellow rain: Thai bees' faeces found". Nature 308 (5959): 485. doi:10.1038/308485b0. PMID 6709055.
- Marshall E (July 1986). "Yellow rain evidence slowly whittled away". Science 233 (4759): 18–9. doi:10.1126/science.3715471. PMID 3715471.
- "Evaluating Mycoherbicides for Illicit Drug Crop Control: Rigorous Scientific Scrutiny is Crucial".
- Imamura Y, Chandra J, Mukherjee PK, Lattif AA, Szczotka-Flynn LB, Pearlman E, Lass JH, O'Donnell K, Ghannoum MA (2008). "Fusarium and Candida albicans Biofilms on Soft Contact Lenses: Model Development, Influence of Lens Type, and Susceptibility to Lens Care Solutions". Antimicrob. Agents Chemother. 52 (1): 171–182. doi:10.1128/AAC.00387-07. PMC 2223913. PMID 17999966.
- Nelson, P E; Dignani, M C; Anaissie, E J (Oct 1994). "Taxonomy, biology, and clinical aspects of Fusarium species". Clin Microbiol Rev 7 (4): 479–504. PMC 358338. Retrieved 3 December 2014.
- Moretti, Antonio (2009). "Taxonomy of Fusarium genus: A continuous fight between lumpers and splitters". Zbornik Matice srpske za prirodne nauke (117): 7–13. doi:10.2298/ZMSPN0917007M. Retrieved 3 December 2014.
- Watanabe, Maiko; Yonezawa, Takahiro; Lee, Ken-ichi; Kumagai, Susumu; Sugita-Konishi, Yoshiko; Goto, Keiichi; Hara-Kudo, Yukiko (2011). "Molecular phylogeny of the higher and lower taxonomy of the Fusarium genus and differences in the evolutionary histories of multiple genes". BMC Evolutionary Biology 11 (1): 322. doi:10.1186/1471-2148-11-322. Retrieved 3 December 2014.
- Summerell, Brett A.; Laurence, Matthew H.; Liew, Edward C. Y.; Leslie, John F. (14 September 2010). "Biogeography and phylogeography of Fusarium: a review". Fungal Diversity 44 (1): 3–13. doi:10.1007/s13225-010-0060-2. Retrieved 3 December 2014.