Bacterial blight (barley)
Encyclopedia
Bacterial blight is a disease of barley
caused by the bacterial pathogen Xanthomonas campestris
pv. translucens (syn. X. translucens). It has been known as a disease since the late 19th century. It has a worldwide distribution.
s expand and then appear as dry dead spots. The lesions elongate into linear streaks which may eventually extend the full length of the leaf
. Lesions rarely occur on the leaf sheath or culm. In severe infections, a milky gray exudate
may be squeezed from the cut end of leaf exhibiting symptoms.
grasses. Spring infection may result from any of these sources. Subsequent infections are spread by splashing of bacterial ooze by rain drops, plant to plant contact and insects.
Bacterial blight develops on the upper leaves of during periods of cool, wet weather, after the plants have reached the boot stage. Leaf blight
is associated with high relative humidity
, wet weather, and cool spring temperatures (15-25 degrees C or 60-75 degrees F). Warm, dry weather stops the disease and new emerging leaves may be relatively free of bacterial infection.
often occurs suggesting that yield losses may reach 10-15%.
, burying crop residue and using disease free seed. No resistant cultivars are known, some are more susceptible than others.
Barley
Barley is a major cereal grain, a member of the grass family. It serves as a major animal fodder, as a base malt for beer and certain distilled beverages, and as a component of various health foods...
caused by the bacterial pathogen Xanthomonas campestris
Xanthomonas campestris
Xanthomonas campestris is a bacterial species that causes a variety of plant diseases. Available from the NCPPB,and other international Culture collections such as ICMP, ATCC, and LMG in a purified form, it is used in the commercial production of a high-molecular-weight polysaccharide - xanthan...
pv. translucens (syn. X. translucens). It has been known as a disease since the late 19th century. It has a worldwide distribution.
Symptoms
The disease is characterized by small, pale green spots or streaks which soon appear water-soaked. The lesionLesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...
s expand and then appear as dry dead spots. The lesions elongate into linear streaks which may eventually extend the full length of the leaf
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....
. Lesions rarely occur on the leaf sheath or culm. In severe infections, a milky gray exudate
Exudate
An exudate is any fluid that filters from the circulatory system into lesions or areas of inflammation. It can apply to plants as well as animals. Its composition varies but generally includes water and the dissolved solutes of the main circulatory fluid such as sap or blood...
may be squeezed from the cut end of leaf exhibiting symptoms.
Disease cycle
This disease is caused by a common bacterium that persists in soil and water and is spread by wind-driven rains. The bacteria overwinters on crop residue, seed, fall-sown cereals, and perennialPerennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
grasses. Spring infection may result from any of these sources. Subsequent infections are spread by splashing of bacterial ooze by rain drops, plant to plant contact and insects.
Bacterial blight develops on the upper leaves of during periods of cool, wet weather, after the plants have reached the boot stage. Leaf blight
Blight
Blight refers to a specific symptom affecting plants in response to infection by a pathogenic organism. It is simply a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. Accordingly, many diseases that primarily exhibit this...
is associated with high relative humidity
Relative humidity
Relative humidity is a term used to describe the amount of water vapor in a mixture of air and water vapor. It is defined as the partial pressure of water vapor in the air-water mixture, given as a percentage of the saturated vapor pressure under those conditions...
, wet weather, and cool spring temperatures (15-25 degrees C or 60-75 degrees F). Warm, dry weather stops the disease and new emerging leaves may be relatively free of bacterial infection.
Crop loss
Although detailed studies have not been conducted, damage to the flagFLAG-tag
FLAG-tag, or FLAG octapeptide, is a polypeptide protein tag that can be added to a protein using recombinant DNA technology. It can be used for affinity chromatography, then used to separate recombinant, overexpressed protein from wild-type protein expressed by the host organism...
often occurs suggesting that yield losses may reach 10-15%.
Management
Disease incidence and severity is reducing by rotating to non-grain cropsCrop (agriculture)
A crop is a non-animal species or variety that is grown to be harvested as food, livestock fodder, fuel or for any other economic purpose. Major world crops include maize , wheat, rice, soybeans, hay, potatoes and cotton. While the term "crop" most commonly refers to plants, it can also include...
, burying crop residue and using disease free seed. No resistant cultivars are known, some are more susceptible than others.