![]() | This article may be expanded with text translated from the corresponding article in Spanish. (June 2010)Click [show] for important translation instructions.
|
Xanthomonas arboricola | |
---|---|
Scientific classification ![]() | |
Domain: | Bacteria |
Phylum: | Pseudomonadota |
Class: | Gammaproteobacteria |
Order: | Xanthomonadales |
Family: | Xanthomonadaceae |
Genus: | Xanthomonas |
Species: | X. arboricola |
Binomial name | |
Xanthomonas arboricola Vauterin et al. 1995 | |
Type strain | |
ATCC 49083 |
Xanthomonas arboricola is a species of bacteria. This phytopathogenic bacterium can cause disease in trees like Prunus , hazelnut and walnut. [1]
Xanthomonas arboricola has a vast host range, however, most symptoms are consistent throughout each of the cultivars such as hazelnut, walnut, and genus prunus (stone fruits). In X. pruni (syn. X. arboricola pv. pruni), the symptoms first usually begin with dark lesions forming on leaves. As the bacteria proliferate, bacterial ooze is noticeable as the necrotic lesions can become greasy. [2] The discharge from the leaf can then spread inoculum to other leaves via rain splash. Infection can lead to an early defoliation of the plant, greatly affecting fruit production. Fruit will also show lesions similar to those found on the leaves. The lesions can cause significant rot of the fruit, thus decreasing or even eliminating any yield. While these are the primary symptoms, sometimes the bacteria can enter the twig over winter, and cause noticeable cankers in the spring; a dieback can happen if the stem cankers are severe enough. [3] [4]
Xanthomonas arboricola can infect all green tissue of the plant. [5] The disease cycle of Xanthomonas arboricola begins on the leaves of the infected plant where the bacteria will live in an epiphytic stage (gathering all nutrients and water from the air) until mid to late spring when sufficient rainsplash spreads the bacteria to new buds and fruits where it becomes pathogenic. With enough early spring rain, a repeating cycle can form in which infected leaves and young buds pass the disease to early season fruit and nutlets. With less rain, a late season infection of fruit and nuts will occur. After the infection of fruit and nuts in autumn, Xanthomonas arboricola will spread to dormant buds and wounds in leaves or branches and overwinter. Come early spring the Xanthomonas will once again enter an epiphytic stage on leaves emerging from previously infected dormant buds and repeat the cycle annually. [5] [6]
Incidence of infection can be correlated with rainfall events during the budding season of the walnut. The most important rains occurring during bud break events. This is due to the rainsplash moving inoculum from infected buds across other green tissues of the tree, most crucially to developing nuts. [7]
Xanthomonas arboricola has an extraordinarily destructive potential when infecting crops. It is the most devastating blight on walnut, and can cause up to 100% yield loss if not properly managed. [3] Its host range threatens stone fruits and other nuts. Epidemics have been reported in countries such as The United States, Iran, Turkey, and Italy. [6] These outbreaks are not limited to just these countries, and without extensive epidemiological knowledge, it could spread with devastating effects. Through disease forecasting efforts, X. arboricola is known to have its highest virulence and growth rate at around 30 degrees Celsius. [8] Temperature in addition to understanding regional humidity, could help prevent future epidemics in agriculture. Less moisture on the plants, and slightly cooler temperatures can hinder both the dispersal and growth of X. arboricola. [8] In Australia an estimated 3.1 million AUD were lost on average due to yield losses from prunusspp. in years with pathogen prevalence. [6] The pathogen’s capability to survive in woody tissue over winter, or after plant death proves a major challenge for plant pathologists to find an effective solution.[ citation needed ]
Current management of bacterial walnut blight caused by Xanthomonas arboricola pv. juglandis is through copper-based bactericide sprays. Spraying is started just prior to early shoot emergence and continued at 7- to 10-day or longer intervals as necessary for disease control according to spring rainfall. [9] This spraying regime is to continue until the end of August. Unfortunately, continuous use of copper-based bactericides lead to a buildup of copper in soil and can be related to yield loss in walnut orchards. [10] A natural antibiotic produced by a strain of Streptomyces by the name of kasumin or kasugamycin has been found to have high efficacy against Xanthomonas arboricola pv. juglandis as a copper spray alternative under dry conditions. However, this same efficacy has not been found to hold up under moderate to heavy rainfall unless paired with a copper-based spray treatment. [11]
With the overall lack of resistance and limited control measures, sanitation and irrigation are one of the most widely recommended modes of management. Proper irrigation and water management can help limit the amount of rain splash to prevent the rapid spread of disease. [6] In preventing epidemics, it is recommended to plant certified propagation material; this inhibits the spread of epiphytic X. arboricola. Sanitation is crucial in stopping the distribution of this disease, given how widespread and destructive it can be. [12]
Active projects are underway to breed for resistance for Xanthomonas arboricola, however, it is difficult to implement resistant varieties of the susceptible hosts. Current efforts to breed resistance have yet to be fully successful. A study in the United States developed partial resistance; all resistance genotypes continued to show at least one symptom. [4] One of the best modes of controlling the spread of the disease is by testing nursery plants for the bacteria before planting. This helps to guarantee that quarantined fields are not introduced to the bacteria by a foreign contaminate. Providing healthy planting material can help stop the relative spread of Xanthomonas arboricola, however, this is good practice and not a definitive solution.[ citation needed ]
Fire blight, also written fireblight, is a contagious disease affecting apples, pears, and some other members of the family Rosaceae. It is a serious concern to apple and pear producers. Under optimal conditions, it can destroy an entire orchard in a single growing season.
Citrus production encompasses the production of citrus fruit, which are the highest-value fruit crop in terms of international trade. There are two main markets for citrus fruit:
A leaf spot is a limited, discoloured, diseased area of a leaf that is caused by fungal, bacterial or viral plant diseases, or by injuries from nematodes, insects, environmental factors, toxicity or herbicides. These discoloured spots or lesions often have a centre of necrosis. Symptoms can overlap across causal agents, however differing signs and symptoms of certain pathogens can lead to the diagnosis of the type of leaf spot disease. Prolonged wet and humid conditions promote leaf spot disease and most pathogens are spread by wind, splashing rain or irrigation that carry the disease to other leaves.
Citrus canker is a disease affecting Citrus species caused by the bacterium Xanthomonas. Infection causes lesions on the leaves, stems, and fruit of citrus trees, including lime, oranges, and grapefruit. While not harmful to humans, canker significantly affects the vitality of citrus trees, causing leaves and fruit to drop prematurely; a fruit infected with canker is safe to eat, but too unsightly to be sold.
Xanthomonas campestris is a bacterium that causes a variety of plant diseases, including "black rot" in cruciferous vegetables and bacterial wilt of turfgrass.
Pseudomonas viridiflava is a fluorescent, Gram-negative, soil bacterium that is pathogenic to plants. It was originally isolated from the dwarf or runner bean, in Switzerland. Based on 16S rRNA analysis, P. viridiflava has been placed in the P. syringae group. Following ribotypical analysis misidentified strains of Pseudomonas syringae pv. ribicola and Pseudomonas syringae pv. primulae were incorporated into this species. This pathogen causes bacterial blight of Kiwifruit.
Xanthomonas is a genus of bacteria, many of which cause plant diseases. There are at least 27 plant associated Xanthomonas spp., that all together infect at least 400 plant species. Different species typically have specific host and/or tissue range and colonization strategies.
Halo blight of bean is a bacterial disease caused by Pseudomonas syringae pv. phaseolicola. Halo blight’s pathogen is a gram-negative, aerobic, polar-flagellated and non-spore forming bacteria. This bacterial disease was first discovered in the early 1920s, and rapidly became the major disease of beans throughout the world. The disease favors the places where temperatures are moderate and plentiful inoculum is available.
Leptosphaeria coniothyrium is a plant pathogen. It can be found around the world.
Xanthomonas fragariae is a species of bacteria. It is a leaf spot disease found in strawberries.
Xylophilus ampelinus is a species of bacteria that can cause plant disease. It is available from the NCPPB in the United Kingdom and other international culture collections such as ICMP in New Zealand, and LMG/BCCM in Belgium.
This article summarizes different crops, what common fungal problems they have, and how fungicide should be used in order to mitigate damage and crop loss. This page also covers how specific fungal infections affect crops present in the United States.
Banana Xanthomonas Wilt (BXW), or banana bacterial wilt (BBW) or enset wilt is a bacterial disease caused by Xanthomonas campestris pv. musacearum. After being originally identified on a close relative of banana, Ensete ventricosum, in Ethiopia in the 1960s, BXW emanated in Uganda in 2001 affecting all types of banana cultivars. Since then BXW has been diagnosed in Central and East Africa including banana growing regions of: Rwanda, Democratic Republic of the Congo, Tanzania, Kenya, Burundi, and Uganda.
Xanthomonas campestris pv. vesicatoria is a bacterium that causes bacterial leaf spot (BLS) on peppers and tomatoes. It is a gram-negative and rod-shaped. It causes symptoms throughout the above-ground portion of the plant including leaf spots, fruit spots and stem cankers. Since this bacterium cannot live in soil for more than a few weeks and survives as inoculum on plant debris, removal of dead plant material and chemical applications to living plants are considered effective control mechanisms.
Bacterial blight of cotton is a disease affecting the cotton plant resulting from infection by Xanthomonas axonopodis pathovar malvacearum (Xcm) a Gram negative, motile rod-shaped, non spore-forming bacterium with a single polar flagellum
Sock Chin Gouk is a research scientist with the Victorian Department of Environment and Primary Industries in Melbourne.
Xanthomonas oryzae pv. oryzae is a bacterial pathovar that causes a serious blight of rice, other grasses, and sedges.
Shot hole disease is a serious fungal disease that creates BB-sized holes in leaves, rough areas on fruit, and concentric lesions on branches. The pathogen that causes shot hole disease is Wilsonomyces carpophilus.
Xanthomonas campestris pv. juglandis is an anaerobic, Gram negative, rod-shaped bacteria that can affect walnut trees though the flowers, buds, shoots, branches, trunk, and fruit. It can have devastating effects including premature fruit drop and lesions on the plant. This pathogen was first isolated by Newton B. Pierce in California in 1896 and was then named Pseudomonas juglandis. In 1905 it was reclassified as Bacterium juglandis, in 1930 it became Phytomas juglandis, and in 1939 it was named Xanthomas juglandis. The International Standards for Naming Pathovars declared it to be named Xanthomonas campestris pv. juglandis in 1980. There have been recent proposals to change the name once again to Xanthomonas arboricola pv. juglandis, but this has not yet been universally accepted.
Xanthomonas pruni is a bacterial disease of almost all Prunus.