Generally speaking, Echinops are not susceptible to many pests or diseases, the only notable issue arises from aphids.
Aphids typically cause damage earlier in the year, where it is not uncommon to see them infesting newly developing leaves causing a distinctive curling and deformation. While such aphid infestations are relatively common, the damage caused is typically not serious and Echinops are usually able to tolerate this damage well.
In all but the most extreme infestations, control is therefore not necessary – often aphids simply disappear of their own accord just as quickly as they appeared. Where extreme damage is being caused however, simple measures such as rubbing the aphids off with your fingers are effective.
Slugs are rarely problematic on Echinops however some small amounts of damage may be caused on new foliage in the Spring and on older foliage as the Autumn sets in. Such damage is typically very limited and almost never requires any action from the gardener.