Susceptibility of apricot cultivars to blossom brown rot (BIOFRUITNET Practice Abstract)

Summary in the original language of the document

Choosing low susceptible cultivars to BBR decreases the risk to economic damage and limits the use of plant
protection products.
Practical recommendation
• Infection: The infection of the flowers depends on climatic conditions (e.g., precipitation, humidity, tem-perature), phenological stages and cultivar susceptibility. The risk of infection is high when it rains between phenological stages D (opening of petals) and F (end of flowering). Symptoms occur around 30-35 days after flowering.
• Diagnostic: Symptoms of BBR can be confused with those of the Pseudomonas canker (PC). However, BBR starts from the tip of the branches, while PC usually starts at the basis of branches. While PC can attack single trees, BBR attacks are broader. The grey mycelium of BBR can be observed on flowers when condi-tions are wet (Picture B). On a petri dish, it appears in several layers (Picture C).
• Cultivars: Prefer a choice of varieties allowing for staggered flowering dates, to limit the risks of a year without harvest. The table below shows the susceptibility of 44 apricot cultivars to BBR, assessed in experiments conducted by GRAB and FiBL. It can be used to help choose cultivars.