Karnal bunt
Encyclopedia
Karnal bunt is a fungal disease of wheat
, durum wheat, and triticale
. The smut fungus
Tilletia indica invades the kernels
and obtains its nutrition from the endosperm
, leaving behind waste products with a disagreeable odor
that makes bunted kernels too unpalatable for use in flour
.
, the district in the India
n state of Haryana
where it was first reported in 1931. It was soon discovered in other nearby wheat-producing regions, including Iraq
, Nepal
, Pakistan
, and Afghanistan
. It was introduced to Mexico
in the 1960s, and it was first discovered in the United States in 1996 in Arizona. Since then, it has also been found in California
, New Mexico
, and Texas
. Quarantine
s, some of them controversial, were imposed there. A few of them have since been lifted, but the USDA
continues to monitor the disease in the United States.
(APHIS) implementing an emergency quarantine, inspection, and certification program for wheat moving out of the infested areas, along with regulations on sanitizing machinery and storage facilities. Many foreign countries have a zero tolerance for karnal bunt in import shipments.
Wheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
, durum wheat, and triticale
Triticale
Triticale is a hybrid of wheat and rye first bred in laboratories during the late 19th century. The grain was originally bred in Scotland and Sweden. Commercially available triticale is almost always a second generation hybrid, i.e., a cross between two kinds of primary triticales...
. The smut fungus
Smut (fungus)
The smuts are multicellular fungi, that are characterized by their large numbers of teliospores. The smuts get their name from a Germanic word for dirt because of their dark, thick-walled and dust-like teliospores. They are mostly Ustilaginomycetes and can cause plant disease...
Tilletia indica invades the kernels
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
and obtains its nutrition from the endosperm
Endosperm
Endosperm is the tissue produced inside the seeds of most flowering plants around the time of fertilization. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. This makes endosperm an important source of nutrition in human diet...
, leaving behind waste products with a disagreeable odor
Odor
An odor or odour is caused by one or more volatilized chemical compounds, generally at a very low concentration, that humans or other animals perceive by the sense of olfaction. Odors are also commonly called scents, which can refer to both pleasant and unpleasant odors...
that makes bunted kernels too unpalatable for use in flour
Flour
Flour is a powder which is made by grinding cereal grains, other seeds or roots . It is the main ingredient of bread, which is a staple food for many cultures, making the availability of adequate supplies of flour a major economic and political issue at various times throughout history...
.
Origin and Spread
Karnal bunt was named after KarnalKarnal
Karnal is an important city and the headquarters of Karnal District in the Indian state of Haryana.Karnal is said to have been founded by the Kauravas in the Mahabharata era for the king Karna, a mythological hero and a key figure in the epic tale...
, the district in the 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...
n state of Haryana
Haryana
Haryana is a state in India. Historically, it has been a part of the Kuru region in North India. The name Haryana is found mentioned in the 12th century AD by the apabhramsha writer Vibudh Shridhar . It is bordered by Punjab and Himachal Pradesh to the north, and by Rajasthan to the west and south...
where it was first reported in 1931. It was soon discovered in other nearby wheat-producing regions, including Iraq
Iraq
Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....
, Nepal
Nepal
Nepal , officially the Federal Democratic Republic of Nepal, is a landlocked sovereign state located in South Asia. It is located in the Himalayas and bordered to the north by the People's Republic of China, and to the south, east, and west by the Republic of India...
, Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
, and Afghanistan
Afghanistan
Afghanistan , officially the Islamic Republic of Afghanistan, is a landlocked country located in the centre of Asia, forming South Asia, Central Asia and the Middle East. With a population of about 29 million, it has an area of , making it the 42nd most populous and 41st largest nation in the world...
. It was introduced to Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
in the 1960s, and it was first discovered in the United States in 1996 in Arizona. Since then, it has also been found in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
, and Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
. Quarantine
Quarantine
Quarantine is compulsory isolation, typically to contain the spread of something considered dangerous, often but not always disease. The word comes from the Italian quarantena, meaning forty-day period....
s, some of them controversial, were imposed there. A few of them have since been lifted, but the USDA
United States Department of Agriculture
The United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
continues to monitor the disease in the United States.
Disease Cycle
The disease is primarily spread through contaminated seed or farm equipment, although it may also be carried short distances by the wind. The fungal spores can then remain viable for several years, germinating when weather conditions become favorable for development. Once the spores germinate, they infest the wheat flowers and develop large masses of spores on the embryo end of the kernels (the entire kernel is not usually affected).Impacts
Karnal bunt has not been shown to have a significant impact on crop yield, although economic losses may occur due to quarantine and export restrictions for infected areas.Regulation
Appearance of the disease in the United States in early 1996 resulted in the Animal and Plant Health Inspection ServiceAnimal and Plant Health Inspection Service
Animal and Plant Health Inspection Service is an agency of the United States Department of Agriculture responsible for protecting animal health, animal welfare, and plant health. APHIS is the lead agency for collaboration with other agencies to protect U.S. agriculture from invasive pests and...
(APHIS) implementing an emergency quarantine, inspection, and certification program for wheat moving out of the infested areas, along with regulations on sanitizing machinery and storage facilities. Many foreign countries have a zero tolerance for karnal bunt in import shipments.