Bacterial leaf scorch (commonly abbreviated BLS, also called bacterial leaf spot) is a disease state affecting many crops, caused mainly by the

xylem Xylem is one of the two types of transport tissue (biology), tissue in vascular plants, the other being phloem; both of these are part of the vascular bundle. The basic function of the xylem is to transport water upward from the roots to parts o ...

-plugging bacterium ''

Xylella fastidiosa ''Xylella fastidiosa'' is an aerobic, Gram-negative bacterium of the genus ''Xylella''. It is a plant pathogen, that grows in the water transport tissues of plants ( xylem vessels) and is transmitted exclusively by xylem sap-feeding insects suc ...

''. It can be mistaken for ordinary ''

leaf scorch Leaf scorch (also called leaf burn, leaf wilt, and sun scorch) is a browning of plant tissues, including leaf margins and tips, and yellowing or darkening of veins which may lead to eventual wilting and abscission of the leaf.

'' caused by cultural practices such as over-fertilization.

Hosts

BLS can be found on a wide variety of hosts, ranging from ornamental trees (

elm Elms are deciduous and semi-deciduous trees comprising the genus ''Ulmus'' in the family Ulmaceae. They are distributed over most of the Northern Hemisphere, inhabiting the temperate and tropical- montane regions of North America and Eurasia, ...

maple ''Acer'' is a genus of trees and shrubs commonly known as maples. The genus is placed in the soapberry family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated si ...

oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

) and shrubs, to crop species including

blueberry Blueberries are a widely distributed and widespread group of perennial flowering plants with blue or purple berries. They are classified in the section ''Cyanococcus'' with the genus ''Vaccinium''. Commercial blueberries—both wild (lowbush) ...

and

almond The almond (''Prunus amygdalus'', Synonym (taxonomy)#Botany, syn. ''Prunus dulcis'') is a species of tree from the genus ''Prunus''. Along with the peach, it is classified in the subgenus ''Amygdalus'', distinguished from the other subgenera ...

. * ''

'' is known to cause BLS in a very wide range of plants. Each of its subspecies has have a different host range. ** The ''multiplex'' subspecies causes BLS of pecans. * Bacterial spot of peppers and tomatoes is caused by the bacteria ''Xanthomonas campestris'' pv. ''vesicatoria'', which has since been divided into four pathovars in three species. * Bacterial spot of peaches is caused by the bacteria ''Xanthomonas arboricola'' pv. ''pruni''. It also infects almonds. Spots may form on the leaves and they can be mistaken for ''

peach scab Peach scab, also known as peach freckles, is a disease of stone fruits caused by the fungi ''Cladosporium carpophilum''. The disease is most prevalent in wet and warm areas especially southern part of the U.S. as the fungi require rain and wind f ...

'', which is caused by a fungus.

Symptoms

An irregular browning leaf margin which may or may not be bordered by a pale

halo HALO, halo, halos or haloes may refer to: Most common meanings * Halo (optical phenomenon) * Halo (religious iconography), a ring of light around the image of a head * ''Halo'' (franchise), a sci-fi video game series (2001–2021) Arts and en ...

. Symptoms re-occur every year, spreading throughout the

tree crown The crown of a plant is the total of an individual plant's aboveground parts, including stems, leaves, and reproductive structures. A plant community canopy consists of one or more plant crowns growing in a given area. The crown of a woody pla ...

, eventually killing the host plant.

Vectors

Xylem Xylem is one of the two types of transport tissue (biology), tissue in vascular plants, the other being phloem; both of these are part of the vascular bundle. The basic function of the xylem is to transport water upward from the roots to parts o ...

-feeding

leafhopper Leafhopper is the common name for any species from the family (biology), family Cicadellidae: based on the type genus ''Cicadella''. These minute insects, colloquially known as hoppers, are plant feeders that suck plant sap from grass, shrubs, or ...

s can transmit the disease bacteria. In general, any xylem-feeding insect can transmit the disease.

Treatment

There are no known effective treatments for BLS, consequently, removal of affected plants is recommended.

References

External links