Causal agent(s) and transmission
Spider mites are small arachnids, usually related to warm and hot climates. Many different species cause local damage to various agricultural crops including the potato. For example, in South America, high populations of the white spider mites, Poliphagotarsonemus latus, induce foliage deformation and brown necroses on leaves (photos 1 and 2).
Similar symptoms are described in North America with other species, such as Tetranychus spp..
Spectacular symptoms of foliage deformation due to spider webs may occur in some African areas.