Weed control is the leading cultural problem facing growers of nursery and landscape plantings. There are weeds for all places in all seasons, including winter annuals, summer annuals, biennials, perennials, grasses, sedges, and broadleaves. If one type is eliminated, another will take its place.
Weeds must be controlled because they can cause direct or indirect reductions in crop growth or quality and because they are aesthetically objectionable. They directly compete with crops for water, nutrients, and light. Some weeds affect the growth of woody plants by producing chemicals that stunt their growth. Weeds indirectly affect crops or landscapes by harboring rodents that may eat the bark of trees and shrubs, causing severe damage or death. Many nursery practices, such as pruning, are complicated by the presence of weeds. Also, weeds slow air movement, which may result in a higher incidence of foliar diseases or frost damage. Aesthetically, weeds create a poor image for a nursery and are generally unacceptable in a landscape.