Hemileia vastatrix
Encyclopedia
Hemileia vastatrix is a fungus
of the order Uredinales that causes coffee rust, a disease that is devastating to coffee plantations. Coffee serves as the obligate host
of coffee rust, that is, the rust must have access to and come into physical contact with coffee (Coffea arabica
) in order to survive.
with uredinia looks yellow-orange and powdery, and appears on the underside of leaves
as points ~0.1 mm in diameter. Young lesions appear as chlorotic or pale yellow spots some millimetres in diameter, the older being a few centimetres in diameter. Hypha
e are club-shaped with tips bearing numerous pedicels on which clusters of urediniospores are produced.
Telia are pale yellowish, teliospore
s often produced in uredinia; teliospores more or less spherical to limoniform, 26–40 × 20–30 µm in diameter, wall hyaline
to yellowish, smooth, 1 µm thick, thicker at the apex, pedicel hyaline.
Urediniospore
s are more or less reniform, 26–40 × 18-28 µm, with hyaline to pale yellowish wall, 1–2 µm thick, strongly warted on the convex side, smooth on the straight or concave side, warts frequently longer (3–7 µm) on spore edges.
Spermogonia and aecia
are unknown.
. It mainly attacks the leaves and is only rarely found on young stems and fruit. Appressoria
are produced which in turn produce vesicles from which entry into the substomatal cavity is gained. Within 24–48 hours, infection is completed. After successful infection, the stoma
tal cavity is colonized and sporulation will occur. One lesion produces 4–6 spore crops over a 3–5 month period releasing 300–400,000 spores.
Probably it does not complete its life-cycle on Coffee tree, but lives on some stage on some other, as yet unknown plant (heteroecious
life-cycle).
, that lives mainly on the plants of genus
Coffea
, reportedly also on Gardenia
in South Africa.
It needs suitable temperatures to develop (not less than 10°C and not greater than 35°C). The presence of free water is required for infection to be completed. Loss of moisture after germination has been initiated inhibits the whole infection process.
Sporulation is most influenced by temperature, humidity, and host resistance. The colonization process is not dependent on leaf wetness, but is influenced greatly by temperature and by plant resistance. The main effect of temperature is to determine the length of time for the colonization process (incubation period
).
Hemileia vastatrix has two fungal parasites, Verticillium
haemiliae and Verticillium psalliotae.
The fungus is probably of East Africa
n origin, but nowadays widely spread in Africa, tropical Asia, Middle- and South-America. Uredospores are disseminated to long distances mainly by wind, and over short distances by both wind and rain. Other agents such as animals, mainly insects and man, occasionally have been shown to be involved with dissemination.
, the Near East, India
, Asia
, and Australia
, the disease was discovered in 1970 to be widespread in Brazil, marking the first known spread to the Western Hemisphere
. Hence it is now found worldwide in virtually all coffee-producing countries.
The disease was first reported in Kenya
in 1861. By 1869 it had spread to Sri Lanka
, and by the 1920s it was widely found across much of Africa and Asia. In the last decades of the nineteenth century, coffee rust did serious damage to the coffee plantations of Sri Lanka
, Philippines
, Java and Malaya
,which led to the collapse of the coffee industry in Lipa, Batangas and almost putting the extinction of the Arabica variety. This led to increased cultivation of alternative crops, notably tea in Sri Lanka, and rubber
in all three places. Liberica, a species cultivated in the Philippines since early in the 19th Century, was found to be resistant and thus rose to prominence in Philippine coffee production by the mid-20th Century. Liberica coffee grown in Batangas is locally known as "Barako" coffee, named after the laborers who worked harvesting and processing the coffee.
as a herbicide
in 1950.
Fungus
A fungus is a member of a large 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, Fungi, which is separate from plants, animals, and bacteria...
of the order Uredinales that causes coffee rust, a disease that is devastating to coffee plantations. Coffee serves as the obligate host
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
of coffee rust, that is, the rust must have access to and come into physical contact with coffee (Coffea arabica
Coffea arabica
Coffea arabica is a species of Coffea originally indigenous to the mountains of Yemen in the Arabian Peninsula, hence its name, and also from the southwestern highlands of Ethiopia and southeastern Sudan. It is also known as the "coffee shrub of Arabia", "mountain coffee" or "arabica coffee"...
) in order to survive.
Morphology
The myceliumMycelium
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...
with uredinia looks yellow-orange and powdery, and appears on the underside of leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
as points ~0.1 mm in diameter. Young lesions appear as chlorotic or pale yellow spots some millimetres in diameter, the older being a few centimetres in diameter. Hypha
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...
e are club-shaped with tips bearing numerous pedicels on which clusters of urediniospores are produced.
Telia are pale yellowish, teliospore
Teliospore
Teliospore is the thick-walled resting spore of some fungi , from which the basidium arises.-Development:They develop in telia ....
s often produced in uredinia; teliospores more or less spherical to limoniform, 26–40 × 20–30 µm in diameter, wall hyaline
Hyaline
The term hyaline denotes a substance with a glass-like appearance.-Histopathology:In histopathological medical usage, a hyaline substance appears glassy and pink after being stained with haematoxylin and eosin — usually it is an acellular, proteinaceous material...
to yellowish, smooth, 1 µm thick, thicker at the apex, pedicel hyaline.
Urediniospore
Urediniospore
Urediniospores are the thinner-walled spores of some fungi: , from which the basidium arises.-Morphology:*Urediniospores are usually consist of two dikaryote nuclei within one constricted cell resembling the number 8 without a septation...
s are more or less reniform, 26–40 × 18-28 µm, with hyaline to pale yellowish wall, 1–2 µm thick, strongly warted on the convex side, smooth on the straight or concave side, warts frequently longer (3–7 µm) on spore edges.
Spermogonia and aecia
Aecium
Aecium is a specialised reproductive structure found in some rusts and smuts which produces aeciospores. In some literature Aecia are also referred to as "cluster cups"....
are unknown.
Life-cycle
Hemileia life-cycle begins with the germination of uredospores through germ pores in the sporeSpore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
. It mainly attacks the leaves and is only rarely found on young stems and fruit. Appressoria
Appressorium
An appressorium is a flattened, hyphal "pressing" organ, from which a minute infection peg grows and enters the host, using turgor pressure capable of punching through even Mylar....
are produced which in turn produce vesicles from which entry into the substomatal cavity is gained. Within 24–48 hours, infection is completed. After successful infection, the stoma
Stoma
In botany, a stoma is a pore, found in the leaf and stem epidermis that is used forgas exchange. The pore is bordered by a pair of specialized parenchyma cells known as guard cells that are responsible for regulating the size of the opening...
tal cavity is colonized and sporulation will occur. One lesion produces 4–6 spore crops over a 3–5 month period releasing 300–400,000 spores.
Probably it does not complete its life-cycle on Coffee tree, but lives on some stage on some other, as yet unknown plant (heteroecious
Heteroecious
A heteroecious parasite is one that requires at least two hosts. The primary host is the host in which the parasite spends its adult life; the other is the secondary host. Both the primary host and an unrelated alternate host are required for the parasite to complete its life cycle...
life-cycle).
Ecology
Hemileia vastatrix is an obligate parasiteObligate parasite
An obligate parasite is a parasitic organism that cannot complete its life cycle without dependence on its host.-See also:*Obligate intracellular parasite*Parasitism*Parasitic plant*Facultative parasite...
, that lives mainly on the plants of genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Coffea
Coffea
Coffea is a genus of flowering plants in the Rubiaceae family. They are shrubs or small trees native to tropical and southern Africa and tropical Asia. Seeds of several species are the source of the popular beverage coffee. Coffee ranks as one of the world's most valuable and widely traded...
, reportedly also on Gardenia
Gardenia
Gardenia is a genus of 142 species of flowering plants in the coffee family, Rubiaceae, native to the tropical and subtropical regions of Africa, southern Asia, Australasia and Oceania....
in South Africa.
It needs suitable temperatures to develop (not less than 10°C and not greater than 35°C). The presence of free water is required for infection to be completed. Loss of moisture after germination has been initiated inhibits the whole infection process.
Sporulation is most influenced by temperature, humidity, and host resistance. The colonization process is not dependent on leaf wetness, but is influenced greatly by temperature and by plant resistance. The main effect of temperature is to determine the length of time for the colonization process (incubation period
Incubation period
Incubation period is the time elapsed between exposure to a pathogenic organism, a chemical or radiation, and when symptoms and signs are first apparent...
).
Hemileia vastatrix has two fungal parasites, Verticillium
Verticillium
Verticillium is a genus of fungi in the division Ascomycota, and are an anamorphic form of the Plectosphaerellaceae family. The genus used to include diverse groups comprising saprobes and parasites of higher plants, insects, nematodes, mollusc eggs and other fungi thus it can be seen that the...
haemiliae and Verticillium psalliotae.
The fungus is probably of East Africa
East Africa
East Africa or Eastern Africa is the easterly region of the African continent, variably defined by geography or geopolitics. In the UN scheme of geographic regions, 19 territories constitute Eastern Africa:...
n origin, but nowadays widely spread in Africa, tropical Asia, Middle- and South-America. Uredospores are disseminated to long distances mainly by wind, and over short distances by both wind and rain. Other agents such as animals, mainly insects and man, occasionally have been shown to be involved with dissemination.
Disease reports
Historically found in coffee-growing areas of AfricaAfrica
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, the Near East, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, and Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, the disease was discovered in 1970 to be widespread in Brazil, marking the first known spread to the Western Hemisphere
Western Hemisphere
The Western Hemisphere or western hemisphere is mainly used as a geographical term for the half of the Earth that lies west of the Prime Meridian and east of the Antimeridian , the other half being called the Eastern Hemisphere.In this sense, the western hemisphere consists of the western portions...
. Hence it is now found worldwide in virtually all coffee-producing countries.
The disease was first reported in Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...
in 1861. By 1869 it had spread to Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
, and by the 1920s it was widely found across much of Africa and Asia. In the last decades of the nineteenth century, coffee rust did serious damage to the coffee plantations of Sri Lanka
Sri Lanka
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
, Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
, Java and Malaya
British Malaya
British Malaya loosely described a set of states on the Malay Peninsula and the Island of Singapore that were brought under British control between the 18th and the 20th centuries...
,which led to the collapse of the coffee industry in Lipa, Batangas and almost putting the extinction of the Arabica variety. This led to increased cultivation of alternative crops, notably tea in Sri Lanka, and rubber
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...
in all three places. Liberica, a species cultivated in the Philippines since early in the 19th Century, was found to be resistant and thus rose to prominence in Philippine coffee production by the mid-20th Century. Liberica coffee grown in Batangas is locally known as "Barako" coffee, named after the laborers who worked harvesting and processing the coffee.
Use as an herbicide
Coffee Rust was used by the USA in GuatemalaGuatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...
as a herbicide
Herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
in 1950.