Types of Turfgrass Weeds

Types of Turfgrass Weeds

There are three types of Turfgrass weeds: grasses, broadleaves, and sedges.

Grasses have leaves with veins that run parallel to each other and are two-ranked (on opposite sides of the stem). The stem is jointed and hollow and the root system is fibrous. Examples included crabgrass, goosegrass, and foxtail.

Broadleaf weeds have leaves with a network of veins which are divided, and generally have a solid stem and main root system. Flowers are usually conspicuous. Dandelion, prostrate spurge, and ground ivy are examples.

Sedges closely resemble grasses in that the leaves have parallel veins. The main difference is that the stem is triangular, solid, and without nodes. In addition, the leaves are three-ranked – arising from each side of the stem. Yellow nutsedge is an example.

Classification

Annuals, Biennials, Perennials

Turfgrass weeds are often grouped by life span. Determining a weed’s life span can be important when developing a management strategy. Weeds are classified as annuals, biennials, and perennials. Annuals have a one-year life cycle. They germinate from seed, mature, and produce seed for the next generation in less than 12 months. Crabgrass, common chickweed, and prostrate knotweed are examples.

Biennials require two years to complete their life cycle. They form a rosette the first year, then follower and die during the second year. Many thistles are biennials.

Perennials are plants which live for more than two years and may live indefinitely. Most perennials grow from seed, but may rise from reproductive structures, such as tubers and rhizomes. Examples include dandelion, quackgrass, and yellow nutsedge.

Cool Season, Warm Season

Weeds can be further classified as cool season or warm season, based on when they germinate or grow most actively. Cool season plants include winter annuals, cool season annuals, and perennials. Winter annuals germinate in the fall, overwinter, then produce seed and dies the following summer. Common chickweed, henbit, and pennycress are examples. Cool season perennials grow best during cool periods and go dormant during the hottest part of summer. Dandelion, rough bluegrass, and white clover are cool season perennials.

Warm season plants include both annuals and perennials. Warm season annuals won’t germinate until soil temperatures warm up in May or June. These include prostrate spurge, purslane, and crabgrass. Warm season perennials remain dormant until June and go dormant again after the first frost. Nimblewill is an example.

Reference

R.E. Gaussoin and A. R. Martin. (1997). Turfgrass Weed Identification and Prevention. In F. Baxendale, Ph.D., & R. Gaussoin, Ph.D., Integrated Turfgrass Management for the Northern Great Plains (pp. 80 – 81). Location: Nebraska