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Identifying weeds

A weed’s life cycle has great impact on the selection and success of a given control procedure, so it is important to learn the life cycle characteristics of a weed when you first learn its identity.

Annual weeds germinate from seeds, grow, flower, produce seeds and die in 12 months or less. Annual weeds are further categorized by the season in which they germinate and flourish. Winter annuals sprout in the fall, thrive during the winter and die in late spring or early summer. Summer or warm-season grasses such as crabgrass and goosegrass sprout in the spring and thrive in summer and early fall.

Perennial weeds are weeds that live more than two years. They reproduce from vegetative (non-seed) parts such as tubers, bulbs, rhizomes (underground stems) or stolons (above-ground stems), although some also produce seed. Perennial weeds are the most difficult to control because of their great reproductive potential and persistence.

Proper identification of weeds targeted for control is necessary in order to select effective control measures, whether cultural or chemical.

Principles of Weed Identification

Weeds can be classified into 3 categories: broadleaf (dicots), grasses (monocots) and sedges.

Leaf shape can vary dramatically and is a consistent key to plant identification. Leaves may be alternate or be opposite each other along the stem. Some leaves may be attached to a short stem, while others will have no stem at all. Leaf surfaces may have small hairs, or no hairs at all and have a waxy-like appearance.

Stems also assist in identification. They have various shapes and amounts of hair if any.

See also: Weed ID Photos




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