Fusarium verticillioides in corn
This fungus, previously known as Fusarium moniliforme, is commonly found in corn seeds. It can be found growing from seeds that germinate normally on germination paper. One study showed that inoculated seeds produced seedlings of reduced size if grown in sterile soil in a reduced light, but not if growing conditions were normal (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC150081). The authors also showed that this fungus would infect the seedlings from soil infested with this species. F. verticillioides is common among dead and weak plant tissue of many plant species including the previous season’s corn debris. Spores (conidia) are prolifically produced on moistened infected tissue and spread within the corn tissue. Any openings in the corn plant is vulnerable to infection by this fungus that easily gets established in the nodal tissue. It is probably not as aggressive as another Fusarium species (F. graminearum) that is better known by its sexual stage (Gibberella zeae).
Fusarium verticillioides is often blamed for causing Fusarium stalk rot, mostly because it is nearly always present and none of the other potential stalk rotting fungi such as Stenocarpella maydis (Diplodia maydis), Gibberella zeae or Colletotrichum graminicola are present in the dead stalk. Because the dead stalk was predisposed to a root rot because of the plants reaction to growing conditions leading to vulnerability to many soil organisms, the identity of the stalk-inhabiting organism may be convenient but the future solution should concentrate on the conditions leading to the root deterioration.
Fusarium verticillioides also infects the developing kernels. Some of this occurred with the spores germinating on the exposed silks and growing into the freshly pollinated kernels. This and other Fusarium species also can reach the kernels within the developing ear through physical damage from insects and birds. Hybrids and environments differ in vulnerability to Fusarium infection of the kernels. F. verticillioides has the potential to produce a toxin called fumonisin in grain.
This fungus is among the occupants of corn plants that are mostly limited by the living corn tissue but ready to digest the senescent and dead tissue.
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The purpose of this blog is to share perspectives of the biology of corn, its seed and diseases in a mix of technical and not so technical terms with all who are interested in this major crop. With more technical references to any of the topics easily available on the web with a search of key words, the blog will rarely cite references but will attempt to be accurate. Comments are welcome but will be screened before publishing. Comments and questions directed to the author by emails are encouraged.