Cultivar Susceptibility and Environmental Parameters Affecting Symptom Expression of Red Leaf Blotch of Almond in Spain.

Red leaf blotch (RLB) of almond, caused by , is an important foliar disease of this nut tree in the Mediterranean basin and Middle East regions. In recent years, the incidence of this disease has increased in Spain, corresponding to increases in the area of newly planted orchards and the use of susceptible cultivars. In 2009, an experimental orchard including 21 almond cultivars was planted at Les Borges Blanques, Lleida, in northeastern Spain.

Inoculum and Infection Dynamics of in Almond Orchards in Spain.

Red leaf blotch (RLB) disease of almond, caused by , is an important foliar disease in most production regions of the Mediterranean basin and the Middle East because severe infections may cause a premature defoliation of the tree. Some key aspects on the epidemiology of . were studied in multiyear trials in two almond-growing regions in Spain, which included the seasonal development of perithecia and production and germination of ascospores along with the disease incubation and plant infectivity periods.

Lignin biosynthesis as a key mechanism to repress Polystigma amygdalinum, the causal agent of the red leaf blotch disease in almond.

The red leaf blotch (RLB) of almond, caused by the fungus Polystigma amygdalinum, is considered as one of the most important leaf diseases of this fruit tree. Differential cultivar susceptibility to the RLB has been described based on field observations, while its molecular and biochemical bases remain unknown to date. We aimed to explore the plant defence mechanisms related to the cultivar susceptibility by identifying some relevant physical and chemical strategies for the pathogen control.