This invention relates to heterocyclic red azo colorants for seed treatment applications. The red azo colorants contain a heterocycle that includes one nitrogen atom and one sulfur atom and are free from electron-withdrawing groups on the heterocycle. Seeds for use in horticultural/agriculture applications that are coated with the heterocyclic azo colorants provide anti-counterfeiting properties to the coated seeds. A color change phenomenon is observed when the coated seeds are exposed to an acidic material, such as vinegar, and provides evidence of the authenticity of the coated seeds. The invention also relates to agricultural formulations containing the heterocyclic red azo colorants that can be used as an anti-counterfeit agents.