Weeds Management: Identifying and Classifying Weeds for Effective Control, Slides of Botany and Agronomy

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Weeds Management

Weeds: Benefits

• Weeds are controversial plants that are neither all good nor all bad, depending on one’s outlook.
• 1. Many weeds can be enjoyed for their attractive flowers and interesting seed pods.
• 2. Weeds quickly grow
• to cover unsightly scars
• on the landscape made
• by man or by nature.

Don’t Let Weeds Ruin Your Day!

For a farmer or gardener to do an effective job of controlling troublesome weeds, exact identification of the weed is important.

The selection of the most effective control method depends on one’s ability to properly identify the problem species.

Identification Is The Key

• The purpose of a weed collection is to help the person making the collection more adept at identifying weeds:
• 1. A simple way to begin identifying common weeds is to compare your specimens against drawings and colored photographs from references.

Weed Classification

• II. The classification of weeds is achieved by grouping together those weeds whose similarities are greater than their differences.

a. Most weeds can be placed into two convenient groups: narrow-leafed or broad- leafed.

• 1. Narrow-leafed weeds include: grasses, sedges, rushes and cattails. All have parallel veins running throughout their leaves.
• 2. Broad-leafed weeds include: most others, such as mustards, dock, pigweed, purslane, and morning glory. All have a net-like pattern of veins running throughout the leaves.

Weed Classification (cont.)

b. Like other plants, weeds have varying types of life cycles:

• 1. Annual weeds live for one year or less.
• 2. Biannual weeds live for two growing seasons.
• 3. Perennial weeds live for 3 or more years.

What’s Your Name? (cont.)

d) Stem variations such as rhizomes, stolons, and tubers are helpful in identification. e) Taproots of the broad-leafed weeds differentiate them from the fibrous roots of grasses. f) The fruits and seeds of weeds are all unique in their shape, size, markings, and color.

The Cotyledon Stage

• III. It is especially helpful to identify weeds while they are in the cotyledon stage because:
• a. The weed can be controlled before it competes with the crops. b. Control measures are more effective and less costly when the weeds are treated during this immature stage of their life cycle.

Annual Bluegrass

Poa Annua

Annual

Cool season

Bermuda Grass

Cynodon dactylon

Perennial

Dormant in the cool season

Broadleaf Plantain

Plantago major

Perennial

Bur Clover

Medicago polymorpha

Annual

Cool season

Common Goundsel

Senecio vulgaris

Annual

Cool season

Crabgrass

Digitaria ischaemum

Annual

Warm season