FEATURED INFORMATION

Stemphylium vesicarium

Isidre Llorente

Institute of Food and Agricultural Technology. University of Girona

Brown spot of pear is a disease caused by the fungus Stemphylium vesicarium (Wallr.) Simmons. This disease affects several European pear-production areas including Catalonia, Portugal, Italy, France, Belgium and Holland. The symptoms are necrotic lesions on leaves and fruits.

Brown spot of pear is a disease caused by the fungus Stemphylium vesicarium (Wallr.) Simmons. This disease affects several European pear-production areas including Catalonia, Portugal, Italy, France, Belgium and Holland. The symptoms are necrotic lesions on leaves and fruits. Lesions on fruits reduce the economic value of the product and can also lead to other microorganisms that cause rotting. The economic losses can be significant, reaching over 10% of total production. Susceptibility to the disease depends on the pear variety, with Fetel Abate, Passe Crassane, Alexandrine and Conference being highly susceptible. The environmental factors conducive to infections are wetness and the temperature during this period. Wetness periods of at least 6 hours are required to initiate infection. The longer the wetness period, the higher the probability of infection. The optimum temperatures for infections are between 20 and 25° C. The main control method is fungicide sprays, such as thiram, captan, strobilurin or others. These fungicides can be applied either at fixed schedule or according to the risk of infection using the BSPcast model. The BSPcast model is used to determine the daily risk of infection according to the wetness period and the mean temperature during this period. Using the BSPcast model to determine treatment application reduces the number of treatments required by 30% on average, to achieve the same disease control as fixed-schedule applications. However, the disease cannot be controlled by fungicides alone. Therefore, integrated disease management combining health practices with use of biocontrol agents and fungicides is proposed. Knowledge of the life cycle of the pathogen is vital for this. The asexual state of the fungus is S. vesicarium (Deuteromycota) and the sexual state is Pleospora allii (Ascomycota). Both states of fungus can be pathogenic to pear trees and saprophytic to a range of dead plant matter. During the vegetative phase of pear trees, the pathogenic phase is highly significant because it causes infections on leaves and fruits in the aerial parts of trees; however, inoculum is primarily formed in dead plant matter on the orchard floor. In late fall and winter, the fungus survives mainly on pear leaf litter and other plant matter on the floor, forming pseudothecia of P. allii that release ascospores the following year. To break this biological cycle, health measures are proposed comprising mechanical removal of plant litter from the floor during the winter and before ascospores are released, and use of biocontrol agents (Trichoderma sp, and others) on the orchard floor during the spring and summer to reduce the production of inoculum. When petalfall begins, fungicide spraying is carried out according to the risk predicted by the BSPcast model to control infections. The pathogenic and saprophytic capacities of S. vesicarium and P. allii make it difficult to control brown spot of pear.

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In accordance with the Organic Law on the Protection of Personal Data 15/1999, of 13 December, Promotora de Exportaciones Catalanas SA (hereinafter PRODECA), whose address is Gran Via de les Corts Catalanes, 620, principal, 08007 Barcelona, with tax reg. no. NIF A58241316, declares that the images contained on the website www.smartfruitcongress.cat are included in a file belonging to PRODECA. The purpose of this file is the promotion, via its website, of the activities conducted by PRODECA – SmartfFruit IPM International Congress.

PRODECA guarantees that you may, at any time, exercise your right to access, rectify, cancel or oppose by writing to the aforesaid postal address, using the reference "PROTECCIÓN DE DATOS - SMARTFRUIT", or to the email address smartfruitcongress@smartfruitcongress.cat.

Specifically, to correctly exercise these rights you must clearly provide the following items in that communication:
- Name, surname(s) and photocopy of National Identity Document or Passport.
- Statement of the purpose of the request.
- Address for notification purposes.
PRODECA also declares that it reserves the right to delete from its website any content that it considers violates current and applicable legislation.

D’acord amb l’article 17.1 de la Llei 19/2014, la ©Generalitat de Catalunya permet la reutilització dels continguts i de les dades sempre que se'n citi la font i la data d'actualització i que no es desnaturalitzi la informació (article 8 de la Llei 37/2007) i també que no es contradigui amb una llicència específica.