CCA Weed Identification and Control 2

Question 1

Which weed is characterized by a triangular stem, making it easily distinguishable from grasses?

Accepted Answer

Yellow nutsedge (Cyperus esculentus)

Answer

Crabgrass (Digitaria sanguinalis)

Answer

Barnyardgrass (Echinochloa crus-galli)

Answer

Foxtail (Setaria spp.)

Question 2

What is the primary mode of action for glyphosate herbicides?

Accepted Answer

Inhibition of EPSP synthase in the shikimate pathway

Answer

Inhibition of acetolactate synthase (ALS)

Answer

Disruption of photosystem II

Answer

Inhibition of acetyl-CoA carboxylase (ACCase)

Question 3

A field scout identifies a broadleaf weed with alternate leaves, a taproot, and milky latex sap. Which weed is most likely present?

Accepted Answer

Common dandelion (Taraxacum officinale)

Answer

Common lambsquarters

Answer

Pigweed (Amaranthus spp.)

Answer

Common ragweed

Question 4

Which herbicide class is best suited for POST-emergence control of grass weeds in broadleaf crops such as soybeans?

Accepted Answer

Graminicides — ACCase inhibitors (Group 1)

Answer

Triazines (Group 5)

Answer

ALS inhibitors (Group 2)

Answer

Synthetic auxins (Group 4)

Question 5

What weed management strategy involves planting competitive crop varieties and optimizing plant populations to suppress weed growth?

Accepted Answer

Cultural weed control

Answer

Allelopathic suppression

Answer

Integrated pest management threshold

Answer

Biological control

Question 6

Which of the following is a C4 summer annual grass weed that thrives in hot, dry conditions and is a common problem in corn and soybean production?

Accepted Answer

Giant foxtail (Setaria faberi)

Answer

Annual ryegrass (Lolium multiflorum)

Answer

Downy brome (Bromus tectorum)

Answer

Wild oat (Avena fatua)

Question 7

The economic threshold concept in weed management is best defined as:

Accepted Answer

The weed density at which the cost of control equals the economic damage caused

Answer

The maximum weed density allowed by law in certified crop production

Answer

The weed density at which a crop begins to show visible injury symptoms

Answer

The population level below which no herbicide efficacy is observed