IPM practices (cultural, mechanical, biological, chemical) are the methods used to execute an IPM strategy. The practices are based on a series of concepts, one of which is pest identification. A “pest” is an insect or other arthropod, plant disease, weed or other organism that negatively affects plant health or becomes an annoyance to people or pets.
The cornerstone of IPM strategy is prevention. Whenever feasible, landscapes including turf and ornamental plantings can be planned, selecting plant species or varieties and landscape elements that are least likely to serve as a pest host or harbor site. Once established, plants should be cared for to reduce or eliminate any stress, to assure plant growth is vigorous and healthy. These are cultural management tactics. Regardless of these preventive measures, insect and other arthropod pests may occur.
In IPM, cultural and physical practices are those activities involved in caring for plants, such as site and cultivar selection, creating habitats for beneficial insects, weeding, watering, nutrient management, etc.
Mechanical practices are the first practices to consider when pests have reach an unacceptable level (action threshold). They include erecting barriers, using traps, hand-picking and other activities that disrupt insect breeding and feeding. For instance, spraying plants with a water hose to knock off aphids and mites is a mechanical practice.
Biological practices include using one organism to control another, as in attracting or releasing beneficial insects that are natural enemies of pest species into the landscape and protecting the beneficials that exist in the landscape.
Chemical Practices 
Chemical practices involve the use of pesticides. In IPM, pesticides are used only when needed and in combination with other approaches for more effective, long-term control. Also, pesticides are selected and applied in a way that minimizes their possible harm to people and the environment. With IPM you’ll use the most selective pesticide that will do the job and be the safest for other organisms and for air, soil, and water quality; use pesticides in bait stations rather than sprays; or spot-spray a few weeds instead of an entire area.
 Source: What Is IPM?, UC IPM Online