''Colletotrichum trifolii'' is a
fungal
A fungus (: fungi , , , or ; 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 one of the tradit ...
plant pathogen of
alfalfa
Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial plant, 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, ...
, causing the disease alfafa anthracnose. It is a biotroph, obtaining nutrients from the living plant cells before forming
asexual
Asexual or Asexuals may refer to:
*Asexual reproduction
**Asexual reproduction in starfish
*Asexuality, the lack of sexual attraction to anyone or lack of interest in or desire for sexual activity.
**Gray asexuality, the spectrum between asexualit ...
spore
In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...
s. This fungus has two known races Bain and Essary.
Hosts and symptoms
Hosts
''Colletotrichum trifolii'' is a pathogen to many forage crops. These include:
*
Alfalfa
Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial plant, 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, ...
(most common)
*
Sweet clover
*
Burr clover
*
Subterranean clover
*
Crimson clover
''Trifolium incarnatum'', known as crimson clover or Italian clover, is a species of herbaceous flowering plant in the family Fabaceae, native to most of Europe. It has been introduced to other areas, including the United States and Japan.
This ...
*
Red clover
''Trifolium pratense'' (from Latin prātum, meaning meadow), red clover, is a herbaceous plant, herbaceous species of flowering plant in the bean family, Fabaceae. It is native to the Old World, but planted and naturalised in many other regions ...
There have been no attempts to discover a full host range outside beyond the aforementioned.
Symptoms
This pathogen causes anthracnose in these plants. The visual symptoms include:
* Scattered straw colored plants in the field
* Yellowing of leaves
* Formation of a "shepherds crook"
* Greyish brown lesions on lower stem leading to crown rot
*
Once parts of the plant die parts of the leaves will turn tan making the black fruiting bodies of ''Colletotrichum trifolii'' especially visible to the observer.
Environment
Anthracnose from ''Colletotrichum trifolii'' most severely affects crops east of the Mississippi River and south of Wisconsin. It is also found in California and southern Arizona and in less severe cases, ''Colletotrichum trifolii'' has a moderate pressure across the whole United States except around the Rocky Mountains. It is also found in Europe, South America, and Canada. This pathogen grows the best around 25 °C. ''Colletotrichum trifolii'' also needs substantial moisture for a minimum of twelve hours to infect the plant although once infected it can survive on the plant in dry weather.
Management
There are only a couple ways to manage ''Colletotrichum trifolii''. The first way is to start scouting right away in early summer. If this pathogen is found in a field rotate crops in the field away from forage crops for at least two year. Another method of management is planting resistant varieties. It is recommended to plant only varieties with a minimum moderate resistant rating but if ''Colletotrichum trifolii'' has been a problem in the past only plant highly resistant varieties.
The last management tactic is to delay planting until after ''Colletotrichum trifolii'' is normally a problem. This means waiting until late summer, around August, doing this allows the plants to become a good stand during late summer and fall while escaping most of the time when the pathogen is prevalent.
This method is not very practical especially with the resistant varieties of today.
References
trifolii
Fungal plant pathogens and diseases
Eudicot diseases
Fungi described in 1906
Fungus species
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