The whole biological spectrum is represented. Pests are organisms that compete with people for food or fiber, interfere with raising our crops and livestock and damage our belongings. Proper identification is important - without proper identification of the pest, control is not possible. B. Introduction to plant pests. Four main groups of pests include weeds, invertebrates, vertebrates, and disease agents.
Most weeds produce a large number of seeds.
Some weed seeds can remain dormant in the soil for 20 years before germinating. Weeds can be persistent and difficult to eradicate, because some have vegetative means of reproduction in addition to seeds. Weeds compete with agricultural crops for water, nutrients, light and space. Some weeds are toxic to livestock. A simple way to identify weeds is to compare them to colored photographs and drawings.