The plant cell wall is a physical barrier, which fulfills a plethora of functions, for example it can efficiently prevent pathogen’s entry into the cell. In addition, its changing composition contributes to plants inducible defense mechanisms. This layer of defense includes pathogen perception and is followed by the activation of defense responses resulting, among others, in a modification and remodeling of the cell wall. This relatively late defense response (hours or days after contact with pathogen) comprises the accumulation of polysaccharides, such as the 1,3-ß-glucan callose, phenolic compounds and reactive oxygen species. Callose depositions occur during normal plant growth (e.g. in the phloem), they can be also a response to different stress stimuli. During the response to pathogen attack, callose depositions are essential part of cell wall reinforcement and are important for successful plant defense. Here, we describe a method to stain callose apposition spots, which can be used to quantify this defense response.