In the southern area of Chile, the most important phytosanitary problem in cherry plantations is the bacterial cancer, which is a severe disease caused by the bacterium Pseudomona syringae pv. Syringae van Hall, and whose foci are found in areas where cold and humid springs predominate, associated with strong winds and permanent humidity.
In wood, damage occurs in the form of cankers on trunks, branches and twigs, which externally are fissures of a different color than the common one of a healthy bark, which, when removed, allows watery spots and pale reddish-brown streaks to be seen at the phloem level, sometimes leading to the death of the entire tree, especially of young plants, and also to a significant reduction in production in adult plants.
Also, it is possible to distinguish other symptoms such as discoloration and softening, amber-colored gummy exudation, which can affect the bark, parenchyma and vascular bundles. In the case of the leaves, necrotic spots of different sizes become visible, surrounded by a chlorotic halo; and yellowing, scalding and defoliation may also occur.
What is the cycle of the bacteria and the damage it causes in the Cherry tree?
Epidemiology in Cerezo It is characterized by a epiphytic phase on tissues or other cultivated hosts and in some weeds, with leaf spots observed throughout the year, alternating with the canker phase, which predominates in winter, the latter being the one that can cause the death of plants.
The Bacterial multiplication in bark tissues occurs in late autumn or early spring., without significant canker development before the spring period. At the beginning of summer, winter cankers, resulting from infection in the previous fall, gradually decrease their activity and growth. Bacteria that remain in buds or near scars, cankers or necrotic tissue will multiply when temperature and humidity conditions are favorable. Infection by this bacteria can also occur significantly through functional structures of the plant such as lenticels and stomata.
Flower blight and shoot dieback, occurs during spring, where infected flowers have a brown, wet appearance, wither and hang from the twig. From the flowers, the bacteria can spread to the shoot, causing a typical dieback. Infected fruit shows browning and soft rot of the stem and drupe.
Pathogenesis, which refers to the development of the disease, is enhanced in localities where they predominate Cold and wet springs, strong winds and frequent humidity such as drizzle and dew; conditions that can occur frequently in many places in the southern part of the country. Therefore, It is very important if you decide to establish a new cherry plantation, to consider in detail the conditions of the specific site, and which may favor the attack of P. syringae.
Next news: Part II of Learning more about Cherry Bacterial Cancer, with a focus on its control.
Acknowledgements: Dr. Jaime Guerrero, Plant Pathologist, Universidad de la Frontera and researcher of the Project Aspects of Sustainability and Efficient Use in Cherry Trees.
For more information about the PTEC66647 Program South Fruit Growing Center Contact Claudia Jorquera [email protected] or Alejandra Vinegar [email protected]
