This course explores the strategies that plants have evolved to defend themselves against microbes and parasitic plants. The course consists of two sections: 1. Plant - pathogenic microbe interactions and 2. Plant - plant parasite interactions. The first section focuses on an in-depth discussion about on-going research of plant immunity against pathogenic microbes. The second section introduces plant - parasitic plant relationships with an emphasis on signalling pathways that underlie these interactions and discusses how basic knowledge of the lifestyle of parasitic plants could contribute to agricultural solutions in the developing world.