**1. Introduction**

*Capsicum* is a genus native to tropical and subtropical America [1], where species such as *C. annuum* L., *C. baccatum* L., *C. chinense* Jacq., *C. frutescens* L., and *C. pubescens* R. & P. [2, 3] excel for its great nutritional, economic [4], and cultural value in the gastronomy of several countries [5]. These vegetables, also commonly known as sweet peppers or hot peppers, can reach a global production of 38 million tons [6]. However, like other crops, peppers are not exempt from disease attacks, caused mainly by viruses, bacteria (leaf spots and vascular wilts), fungi (cercosporiosis,

powdery mildew and anthracnose), and mainly pseudofungi (rot of roots, stems and fruits; and, leaf blight) [7].

*Phytophthora capsici* is an oomycete present in several parts of the world, being reported as the causal agent of countless diseases in different crops of agricultural importance such as Cucurbitaceae, Rosaceae, Fabaceae, Liliaceae and Solanaceae [8]. This phytopathogen in *Capsicum* can cause damage of up to 100% due to its rapid spread in field conditions and represents around \$100 million in losses [9, 10] for which it is considered the fifth most destructive oomycete in the world [11]. Due to the reach of aerial tissues, its polycyclic characteristic makes *P. capsici* one of the most complex phytopathogens to be managed [12].

Resistant plants can generally activate different biochemical, structural and molecular defense mechanisms against the infection of *P. capsici* [13, 14]; conversely, susceptible plants can be infected and colonized by the pathogen. Since most of the common commercial genotypes of *Capsicum* are susceptible, i.e. Chinese Giant (CG), California Wonder (CW), Osh Kosh (OK) and Yolo Wonder (YW), farmers use a considerable amount of oomyceticides to control its attack [3]. However, there are other measures that can be used in an integrated manner to drastically reduce infection of *P. capsici* i.e. crop rotation, irrigation management, use of biocontrole agents, among others. For example, the rate of progress of collar rot in *Capsicum* plants can be reduced considerably by applying *Trichoderma harzianum* [15, 16]. Therefore, due to the importance of *P. capsici* in *Capsicum* spp., this chapter address the etiology, symptomatology, worldwide occurrence and biological cycle of the pathogen in the different plant tissues; and, finally describes the disease management measures to be used either in isolation or integrated approach.
