Weed Identification and Control Flashcards
7 cards from real CCA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Weed Identification and Control flashcards as text
Which weed is characterized by a triangular stem, making it easily distinguishable from grasses?
Answer: Yellow nutsedge (Cyperus esculentus)
Yellow nutsedge belongs to the sedge family (Cyperaceae) and has a distinctly triangular stem cross-section, unlike true grasses which have round or flattened stems.
What is the primary mode of action for glyphosate herbicides?
Answer: Inhibition of EPSP synthase in the shikimate pathway
Glyphosate inhibits 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase, blocking aromatic amino acid synthesis in the shikimate pathway.
A field scout identifies a broadleaf weed with alternate leaves, a taproot, and milky latex sap. Which weed is most likely present?
Answer: Common dandelion (Taraxacum officinale)
Common dandelion produces milky latex sap when stems or leaves are broken, and has a characteristic deep taproot with a basal rosette of leaves.
Which herbicide class is best suited for POST-emergence control of grass weeds in broadleaf crops such as soybeans?
Answer: Graminicides — ACCase inhibitors (Group 1)
Graminicides (ACCase inhibitors) such as clethodim and sethoxydim selectively control grass weeds in broadleaf crops without injuring the crop.
What weed management strategy involves planting competitive crop varieties and optimizing plant populations to suppress weed growth?
Answer: Cultural weed control
Cultural weed control uses agronomic practices—including competitive varieties, optimum seeding rates, and row spacing—to reduce the competitive advantage of weeds.
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?
Answer: Giant foxtail (Setaria faberi)
Giant foxtail is a C4 summer annual grass that is highly competitive in corn and soybean, producing large numbers of seeds and thriving in warm conditions.
The economic threshold concept in weed management is best defined as:
Answer: The weed density at which the cost of control equals the economic damage caused
The economic threshold is the weed density at which crop yield losses equal the cost of the control measure, providing a guide for when treatment is economically justified.