Resistance that spreads uniformly against all pathogen races has been studied and documented in J.E. van der Plank’s book “Plant Diseases: Epidemics and Control” published in 1963 by Academic Press in New York and London. Another form of resistance, known as vertical resistance, refers to the absence of differential interactions when subjected to an analysis of variance on a series of pathotypes and corresponding pathodemes, according to Robinson’s study in 1969. The terms “vertical” and “horizontal” resistance were derived from van der Plank’s graphic representation of the relationship between pathogen races and host plant varieties. It should be noted that horizontal resistance has a quantitative effect, which reduces the rates of infection, increases incubation times, reduces pathogen reproduction rates, and consequently slows down the spread of an epidemic. Although horizontal resistance is usually polygenic, it is not always the case, and the terms “horizontal” and “polygenic” are not synonymous. Field resistance and horizontal resistance are not interchangeable, despite the fact that field resistance is often of the horizontal type. Nevertheless, the term “race non-specific resistance” is equivalent to horizontal resistance and is preferred due to its descriptive nature.