Fusarium patch
Encyclopedia
Fusarium patch is a disease in turf grass settings called pink snow mold, Microdochium patch or Fusarium patch. Microdochium nivale is the pathogen that causes this disease in many cool season turf grass
species in North America. The white-pink mycelium
on infected leaf blades is a distinguishing characteristic of the Microdochium nivale pathogen. Fusarium patch is considered economically important in the turf grass
industry because of its tendency to cause significant injury to golf greens, thereby decreasing putting surface quality. Dissimilar from other snow molds, such as gray snow mold, Microdochium nivale does not need snow cover to cause widespread infection.
), perennial ryegrass (Lolium perenne
) and creeping bentgrass (Agrostis stolonifera
) are more susceptible. In the fall, M.nivale infection begins as small, orange to red-brown spots, circular and only a few centimeters in diameter. During the winter and into the spring seasons, well-defined, clustered, circular patches 10-20 cm in diameter, of necrotic
leaf tissues form on mown turf. Microdochium nivale is mostly seen on grasses mown at heights of three inches or greater. On taller grass, patches often lack a circular pattern that is seen in shorter mown grass Pink snow mold patches usually follow drainage patterns since conidia
spores are readily dislodged and transported by rainfall and water flowage. Under prolonged cool and wet conditions, white-pink mycelium
can be observed along the circumference of diseased patches
mycelium
or spores. When cool, wet weather arrives in the fall or winter it favors the development of asexual spores called conidia
on conidiophores from the mycelium
. These conidia
infect leaf sheaths and blades near the soil. Since this disease is an ascomycete
it also has a sexual spore stage called an ascospore
. These ascospores
develop in a perithecia
; a flask shaped ascocarp
also used as an overwintering structure. The perithecia
are located on the basal leaf sheaths and will eventually release the ascospore
. These ascospore
can infect the upper leaves in early spring or summer if the cool, wet conditions prevail. The spores can be carried to surrounding leaves by way of wind or surface water. It should be dually noted that both conidia
and ascospore
give rise to hyphae
as they germinate
and the resulting hyphae
can also infect the host.
applications in an attempt to decrease the growth of grass and promote dormancy can help decrease the incidence of Pink Snow Mold. In regions of high humidity and temperatures ranging between 32 to 46 degrees Fahrenheit, Pink Snow Mold will develop rapidly.
. IPM
uses a combination of chemical, cultural and biological controls to reduce spending on pesticides and to decrease pesticide resistance
. The following are some of the most important cultural controls used in managing Microdochium Patch.
Cultural Controls
Raising the mowing height is an easy way to reduce stress on a turfgrass plant and make the plant less susceptible to attack by disease. The higher the turf is mowed, the less the plant is prone to disease. Managing the moisture available to the plant is another way to help reduce the incidence of disease. The pathogen that causes Microdochium Patch requires and thrives in moist conditions, therefore making sure that you aren’t overwatering the turf when conditions are right for infection is very important. Giving the plant only enough water for normal plant function is the best way to ensure disease pressure is reduced as much as possible. Also, starving the turf of moisture can be damaging as this increases susceptibility to infection. Managing the amount of nitrogen
available to the plant is another key to decreasing incidence
of this disease. Avoiding excess fall nitrogen
application will greatly reduce disease pressure of Microdochium nivale. On top of that excess nitrogen
available to plant produces rapid growth of above ground tissue. This tissue often has thin cell walls
and is prone to attack by disease. Managing thatch and soil drainage are two other important ways of controlling this disease as both of these affect the amount of moisture that is available to create a favorable environment to the disease Despite the fact that the above cultural controls cannot completely control Microdochium Patch, when they are all used to reduce disease pressure, they can have a noticeable impact and will help to reduce the amount of chemical control that is required.
Chemical controls Chemical controls (i.e. the use of fungicides
) to specifically control turfgrass diseases have been around since 1891 with the introduction of mercury chloride as a broad spectrum control. Heavy metal fungicides
worked very well, but once it was determined that they were bad for the environment, their use stopped. Over the years better and better controls have been developed, all of which tend to be less toxic to animals and the environment when used properly.
There is a wide variety of chemical groups that are labeled for control of Microdochium Patch. They include, but are not limited to the methyl benzimidazole carbamates (MBCs) such as thiophanate methyl, the dicarboximides such as iprodione and vinclozolin, the DMIs such as fenarimol and propiconazole, the QoIs such as azoxystrobin, pyraclostrobin, and trifloxystrobin, the phenylpyrroles such as fludioxonil, certain aromatic hydrocarbons such as PCNB, and the cholronitriles such as chlorothalonil
These chemical classes should be rotated so that selection pressure on the disease in limited as to avoid resistant strains of this disease. The applicator should read and follow all label rates and directions. Breaking these directions and misuse of any labeled product is breaking the law. Remember that the label is the law. The best way to control Microdochium Patch especially going into winter is to use a three way spray right before the first snow fall. A combination of a Dicarboxamide such as iprodione, a chloronitrile such as chlorothalonil, and a DMI such as propiconazole will give sufficient control over the span of an average winter.
) and Annual Bluegrass (Poa annua
). It is of particular concern because turf on golf courses is considered a high value crop. Diseases such a Microdochium Patch lower the value of the crop by decreasing its aesthetic value, affecting the playability, and decreasing the overall health of the turf. Because golf course budgets are often quite tight, the reduction of fungicide applilcations required in a season for snow mold will result in more money elsewhere in the budget. Being that the fungicide budget can be 10% of the maintenance budget, reductions in the use of fungicides can cause a significant increase in the amount of money to do other things. On top of that reducing fungicide inputs helps keep the environment safe.
Lawn
A lawn is an area of aesthetic and recreational land planted with grasses or other durable plants, which usually are maintained at a low and consistent height. Low ornamental meadows in natural landscaping styles are a contemporary option of a lawn...
species in North America. The white-pink mycelium
Mycelium
thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...
on infected leaf blades is a distinguishing characteristic of the Microdochium nivale pathogen. Fusarium patch is considered economically important in the turf grass
Lawn
A lawn is an area of aesthetic and recreational land planted with grasses or other durable plants, which usually are maintained at a low and consistent height. Low ornamental meadows in natural landscaping styles are a contemporary option of a lawn...
industry because of its tendency to cause significant injury to golf greens, thereby decreasing putting surface quality. Dissimilar from other snow molds, such as gray snow mold, Microdochium nivale does not need snow cover to cause widespread infection.
Hosts and symptoms
M. nivale can infect all cool-season turf grass species. Annual bluegrass (Poa annuaPoa annua
Poa annua, or annual meadow grass , is a widespread low-growing turfgrass in temperate climates. Though P. annua is commonly considered a solely annual plant due to its name, perennial bio-types do exist. 'Poa' is Greek for fodder. It is one of the sweetest grasses for green fodder, but less ...
), perennial ryegrass (Lolium perenne
Lolium perenne
Lolium perenne, common name Perennial Ryegrass, is a grass from the family Poaceae. It is native to Europe, Asia and northern Africa, but is widely cultivated and naturalised around the world.-Description:...
) and creeping bentgrass (Agrostis stolonifera
Agrostis stolonifera
Agrostis stolonifera is a perennial grass species in the Poaceae family. It is stoloniferous and may form mats or tufts...
) are more susceptible. In the fall, M.nivale infection begins as small, orange to red-brown spots, circular and only a few centimeters in diameter. During the winter and into the spring seasons, well-defined, clustered, circular patches 10-20 cm in diameter, of necrotic
Necrosis
Necrosis is the premature death of cells in living tissue. Necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma. This is in contrast to apoptosis, which is a naturally occurring cause of cellular death...
leaf tissues form on mown turf. Microdochium nivale is mostly seen on grasses mown at heights of three inches or greater. On taller grass, patches often lack a circular pattern that is seen in shorter mown grass Pink snow mold patches usually follow drainage patterns since conidia
Conidium
Conidia, sometimes termed conidiospores, are asexual, non-motile spores of a fungus and are named after the greek word for dust, konia. They are also called mitospores due to the way they are generated through the cellular process of mitosis...
spores are readily dislodged and transported by rainfall and water flowage. Under prolonged cool and wet conditions, white-pink mycelium
Mycelium
thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...
can be observed along the circumference of diseased patches
Disease cycle
M. nivale begins by oversummering (surviving the summer) in thatch or soil as haploidPloidy
Ploidy is the number of sets of chromosomes in a biological cell.Human sex cells have one complete set of chromosomes from the male or female parent. Sex cells, also called gametes, combine to produce somatic cells. Somatic cells, therefore, have twice as many chromosomes. The haploid number is...
mycelium
Mycelium
thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...
or spores. When cool, wet weather arrives in the fall or winter it favors the development of asexual spores called conidia
Conidium
Conidia, sometimes termed conidiospores, are asexual, non-motile spores of a fungus and are named after the greek word for dust, konia. They are also called mitospores due to the way they are generated through the cellular process of mitosis...
on conidiophores from the mycelium
Mycelium
thumb|right|Fungal myceliaMycelium is the vegetative part of a fungus, consisting of a mass of branching, thread-like hyphae. The mass of hyphae is sometimes called shiro, especially within the fairy ring fungi. Fungal colonies composed of mycelia are found in soil and on or within many other...
. These conidia
Conidium
Conidia, sometimes termed conidiospores, are asexual, non-motile spores of a fungus and are named after the greek word for dust, konia. They are also called mitospores due to the way they are generated through the cellular process of mitosis...
infect leaf sheaths and blades near the soil. Since this disease is an ascomycete
Ascomycota
The Ascomycota are a Division/Phylum of the kingdom Fungi, and subkingdom Dikarya. Its members are commonly known as the Sac fungi. They are the largest phylum of Fungi, with over 64,000 species...
it also has a sexual spore stage called an ascospore
Ascospore
An ascospore is a spore contained in an ascus or that was produced inside an ascus. This kind of spore is specific to fungi classified as ascomycetes ....
. These ascospores
Ascospore
An ascospore is a spore contained in an ascus or that was produced inside an ascus. This kind of spore is specific to fungi classified as ascomycetes ....
develop in a perithecia
Ascocarp
An ascocarp, or ascoma , is the fruiting body of an ascomycete fungus. It consists of very tightly interwoven hyphae and may contain millions of asci, each of which typically contains eight ascospores...
; a flask shaped ascocarp
Ascocarp
An ascocarp, or ascoma , is the fruiting body of an ascomycete fungus. It consists of very tightly interwoven hyphae and may contain millions of asci, each of which typically contains eight ascospores...
also used as an overwintering structure. The perithecia
Ascocarp
An ascocarp, or ascoma , is the fruiting body of an ascomycete fungus. It consists of very tightly interwoven hyphae and may contain millions of asci, each of which typically contains eight ascospores...
are located on the basal leaf sheaths and will eventually release the ascospore
Ascospore
An ascospore is a spore contained in an ascus or that was produced inside an ascus. This kind of spore is specific to fungi classified as ascomycetes ....
. These ascospore
Ascospore
An ascospore is a spore contained in an ascus or that was produced inside an ascus. This kind of spore is specific to fungi classified as ascomycetes ....
can infect the upper leaves in early spring or summer if the cool, wet conditions prevail. The spores can be carried to surrounding leaves by way of wind or surface water. It should be dually noted that both conidia
Conidium
Conidia, sometimes termed conidiospores, are asexual, non-motile spores of a fungus and are named after the greek word for dust, konia. They are also called mitospores due to the way they are generated through the cellular process of mitosis...
and ascospore
Ascospore
An ascospore is a spore contained in an ascus or that was produced inside an ascus. This kind of spore is specific to fungi classified as ascomycetes ....
give rise to hyphae
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...
as they germinate
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
and the resulting hyphae
Hypha
A hypha is a long, branching filamentous structure of a fungus, and also of unrelated Actinobacteria. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium; yeasts are unicellular fungi that do not grow as hyphae.-Structure:A hypha consists of one or...
can also infect the host.
Environment
Microdochium nivale becomes problematic when turf experiences lengthy periods of cool, wet weather typical of fall or spring and into early summer. The name is somewhat confusing because the presence of snow is not necessary for this pathogen to develop. The disease tends to develop proficiently when grass is growing at a slower than normal rate. The disease can thrive under snow cover if it is on unfrozen soil that has thriving turf present. Limiting fall NNitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
applications in an attempt to decrease the growth of grass and promote dormancy can help decrease the incidence of Pink Snow Mold. In regions of high humidity and temperatures ranging between 32 to 46 degrees Fahrenheit, Pink Snow Mold will develop rapidly.
Management
There are a number of different ways to manage diseases including cultural, chemical, and biological controls. Some of these controls are more effective than others, however, the best approach to a managing any disease, including Microdochium Patch, is an integrated approach called Integrated Pest Management or IPMIntegrated Pest Management
Integrated pest management is an ecological approach to agricultural pest control that integrates pesticides/herbicides into a management system incorporating a range of practices for economic control of a pest...
. IPM
Integrated Pest Management
Integrated pest management is an ecological approach to agricultural pest control that integrates pesticides/herbicides into a management system incorporating a range of practices for economic control of a pest...
uses a combination of chemical, cultural and biological controls to reduce spending on pesticides and to decrease pesticide resistance
Pesticide resistance
Pesticide resistance is the adaptation of pest population targeted by a pesticide resulting in decreased susceptibility to that chemical. In other words, pests develop a resistance to a chemical through natural selection: the most resistant organisms are the ones to survive and pass on their...
. The following are some of the most important cultural controls used in managing Microdochium Patch.
Cultural Controls
Cultural controls
In agriculture cultural control is the practice of modifying the growing environment to reduce the prevalence of unwanted pests. Examples include changing soil pH or fertility levels, irrigation practices, amount of sunlight, or temperature...
Raising the mowing height is an easy way to reduce stress on a turfgrass plant and make the plant less susceptible to attack by disease. The higher the turf is mowed, the less the plant is prone to disease. Managing the moisture available to the plant is another way to help reduce the incidence of disease. The pathogen that causes Microdochium Patch requires and thrives in moist conditions, therefore making sure that you aren’t overwatering the turf when conditions are right for infection is very important. Giving the plant only enough water for normal plant function is the best way to ensure disease pressure is reduced as much as possible. Also, starving the turf of moisture can be damaging as this increases susceptibility to infection. Managing the amount of nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
available to the plant is another key to decreasing incidence
Incidence
Incidence may refer to:* Incidence , a measure of the risk of developing some new condition within a specified period of time* Incidence , the binary relations describing how subsets meet...
of this disease. Avoiding excess fall nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
application will greatly reduce disease pressure of Microdochium nivale. On top of that excess nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
available to plant produces rapid growth of above ground tissue. This tissue often has thin cell walls
Cell wall
The cell wall is the tough, usually flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection, and also acts as a filtering mechanism. A major function of the cell wall is to...
and is prone to attack by disease. Managing thatch and soil drainage are two other important ways of controlling this disease as both of these affect the amount of moisture that is available to create a favorable environment to the disease Despite the fact that the above cultural controls cannot completely control Microdochium Patch, when they are all used to reduce disease pressure, they can have a noticeable impact and will help to reduce the amount of chemical control that is required.
Chemical controls Chemical controls (i.e. the use of fungicides
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
) to specifically control turfgrass diseases have been around since 1891 with the introduction of mercury chloride as a broad spectrum control. Heavy metal fungicides
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
worked very well, but once it was determined that they were bad for the environment, their use stopped. Over the years better and better controls have been developed, all of which tend to be less toxic to animals and the environment when used properly.
There is a wide variety of chemical groups that are labeled for control of Microdochium Patch. They include, but are not limited to the methyl benzimidazole carbamates (MBCs) such as thiophanate methyl, the dicarboximides such as iprodione and vinclozolin, the DMIs such as fenarimol and propiconazole, the QoIs such as azoxystrobin, pyraclostrobin, and trifloxystrobin, the phenylpyrroles such as fludioxonil, certain aromatic hydrocarbons such as PCNB, and the cholronitriles such as chlorothalonil
These chemical classes should be rotated so that selection pressure on the disease in limited as to avoid resistant strains of this disease. The applicator should read and follow all label rates and directions. Breaking these directions and misuse of any labeled product is breaking the law. Remember that the label is the law. The best way to control Microdochium Patch especially going into winter is to use a three way spray right before the first snow fall. A combination of a Dicarboxamide such as iprodione, a chloronitrile such as chlorothalonil, and a DMI such as propiconazole will give sufficient control over the span of an average winter.
Importance
Microdochium Patch is a significant problem in the turfgrass management industry. Sports fields, sod farms and home lawns and golf courses can all be damaged by this the disease. The highest incidence of this disease occurs on golf courses due to the highly managed areas of susceptible turfgrass species such as Creeping Bentgrass (Agrostis stoloniferaAgrostis stolonifera
Agrostis stolonifera is a perennial grass species in the Poaceae family. It is stoloniferous and may form mats or tufts...
) and Annual Bluegrass (Poa annua
Poa annua
Poa annua, or annual meadow grass , is a widespread low-growing turfgrass in temperate climates. Though P. annua is commonly considered a solely annual plant due to its name, perennial bio-types do exist. 'Poa' is Greek for fodder. It is one of the sweetest grasses for green fodder, but less ...
). It is of particular concern because turf on golf courses is considered a high value crop. Diseases such a Microdochium Patch lower the value of the crop by decreasing its aesthetic value, affecting the playability, and decreasing the overall health of the turf. Because golf course budgets are often quite tight, the reduction of fungicide applilcations required in a season for snow mold will result in more money elsewhere in the budget. Being that the fungicide budget can be 10% of the maintenance budget, reductions in the use of fungicides can cause a significant increase in the amount of money to do other things. On top of that reducing fungicide inputs helps keep the environment safe.
External links
- More Information on Lawn Care and Fusarium Patch
- Additional Information on Microdochium Patch
- Additional Information on Microdochium Patch
- Additional Information on Management of Microdochium Patch
- Additional Information on Microdochium Patch
- http://www.sciencedirect.com.ezproxy.library.wisc.edu/science/article/pii/S0168945210002323
- http://www.ces.purdue.edu/extmedia/BP/BP-102-W.pdf
- http://www.ces.purdue.edu/extmedia/BP/BP-102-W.pdf
- Index Fungorum
- USDA ARS Fungal Database