Crown crown disease is known as the most harmful bacterial disease of the twentieth century. The factor is the bacterium Agrobacterium tumefaciens, which has the highest number of host plants among bacteria and attacks 634 species of 331 genera and 93 plant families, from woody (fruit or non-fruit) to crops such as sugar beet. The main host of this bacterium is dwarf plants and only 3% of monocotyledonous plants are susceptible to it.
This bacterium has an economic significance in at least 40 plant species of Rose, Clove, Native Fruit, Grain, Grain, Grain and Fig. In dried fruit trees, walnuts, almonds and pecans are more common in rare hazelnuts and pistachios.
This bacterium is in cloves, hair, figs ; Rose becomes systemic. The disease of the crown in the garden, especially in the treasury, has a high economic significance.
In areas where frost damage occurs, the disease is more prevalent. The outbreak in these areas is probably due to the fact that cold and frost causes scars and cracks in the vine, which is a good place for bacterial infiltration of the disease.
Agrobacterium Tumefaciens Bacterium
The A. tumefaciens bacterium belongs to the Proteobacteria family, the rhizobia family, the alphaproteobacteria and the rhizobal stripe. Over the past 100 years, the classification of Agrobacterium has undergone many changes.
This genus was initially based on the pathogenicity of the four species, including A. tumefaciens (Gallia in many herbs), A. rubi (Galza in Raspberry), A. rhizogenes (Root), A. Radiobacter (non-pathogenic) ; It was later divided into A. larrymoorei (aerial galactic in figs;) ;
It was also added. Then, based on biochemical and physiological properties, some species were divided into several germs. Beverages 1 and 2 generally have a wide range of hosts, and Beaver 3 is only pathogenic in hair, raspberry, and clove. In the A. tumefaciens species, barns 1 and 2 are galactic in walnuts, and Beaver 1 is more likely to damage 2 paradoxes in the California walnut gardens.
In 2001, Young and colleagues transmitted the species of Agrobacterium spp. To the genus Rhizobium (nitric stabilizing bacteria in the root of the legumes).
But, according to Farrand et al., In 2003, the reasons for the displacement of Agrobacterium Tumefaciens species were inadequate and was retained under the name Agrobacterium Tumefaciens.At present, due to differences of opinion, this species has a two-named naming system.
Glaucous disease is a global spread. The disease was known in the United States and Europe since the 1880s, but detailed studies have begun to be launched since the 1890s and the disease was first isolated in the United States in 1907.
The cost of the disease was multi-million dollar a year, and only in 1976, it inflicted $ 23 million on plants in California, which was recognized as the most damaging US bacterial disease in the 1975-77 period.
In 2000, 30% of California nut trees were infected with galls, and 95% of California’s nuts were down. This contamination is also widespread in the California walnut treasures, and since galder trees are unattainable, the economic damage to the treasury is very high.
The most prominent symptom of the disease is the appearance of meaty galls. These glands are initially tiny and almost spherical and appear on the root, branch, petiole and stem, especially near the crown.
The tubers are small, white, soft and fleshy, but enlarged and sometimes they reach 30 centimeters.
The tubers formed on the adjacent tissues cause the collapse of the wooden doorways and the deformation of adjacent tissues. The outer surface of the tubers is brownish to black due to external contamination.Due to the formation of the tubers in the injured areas, it is not easy to detect them from the recovering tissue at first.
The plant is less developed and its leaves are small and yellow. The grape clusters of the stems are contaminated, thinned , and sometimes the fruit dries on the stem of the patient. Symptoms appear more on the stems and roots of the plant two or more years old. Destroys plant disease for many years.
The bacteria have been causing winter disease and can survive for many years even if they do not have access to the host.
In the case of planting, the bacterial host plant can enter the root or stem of the plant through wounds caused by gardening, frostbite, insect bites and natural factors such as hail. Infiltration of the bacteria into the tissues of the plant stimulates the adjacent cells to break down.