Weed-Free Lawns Challenge Quiz

Sharpen your understanding of effective and safe lawn weed control practices in horticulture with these medium-difficulty questions. Evaluate knowledge on identification, prevention, and management strategies for common turf weeds.

1. Identifying Common Broadleaf Lawn Weeds

   Which of the following weeds is classified as a broadleaf species commonly found in turfgrass and has a characteristic rosette leaf arrangement and yellow flowers?

   1. Nimblewill
   2. Dandelion
   3. Annual bluegrass
   4. Crabgrass

   Explanation: Dandelion is a broadleaf weed that grows in rosettes and has notable yellow flowers. Crabgrass and nimblewill are grassy weeds, while annual bluegrass is also a grass weed, making them incorrect choices for this broadleaf weed question.

2. Lawn Mowing and Weed Suppression

   Why is mowing the lawn at a higher recommended height effective for weed control in established turfgrass?

   1. It removes all weed seeds
   2. It encourages weed growth
   3. It dries out the lawn
   4. It shades the soil, reducing weed seed germination

   Explanation: A higher mowing height helps the turf grass shade the soil, making conditions less favorable for weed seeds to sprout. Removing all weed seeds is unrealistic with mowing. Encouraging weed growth and drying out the lawn are incorrect and can lead to poorer turf health.

3. Selective Herbicide Use

   Which practice best prevents damage to lawn grass when applying selective herbicides for broadleaf weed control?

   1. Apply during drought stress
   2. Apply when grass and weeds are actively growing
   3. Use at double the labeled rate
   4. Use non-selective herbicide only

   Explanation: Applying herbicides when both grass and weeds are actively growing maximizes weed control while minimizing turf damage. Using excessive rates can harm grass, drought application increases injury risk, and non-selective herbicides harm both weeds and desirable grass.

4. Pre-emergent Herbicides in Spring

   When is the optimal time to apply pre-emergent herbicides to prevent annual grassy weeds like crabgrass in a lawn?

   1. After first frost in autumn
   2. Mid-winter during dormancy
   3. Late summer after weeds appear
   4. Early spring before weed seeds germinate

   Explanation: Pre-emergent herbicides are most effective when applied in early spring before weed seeds germinate. Applying after weeds are visible or out of season (summer, winter, autumn) will not prevent emergence and is less effective.

5. Cultural Practices for Lawn Health

   Which cultural strategy most effectively reduces the spread of weeds in established lawns over time?

   1. Maintaining dense, healthy turfgrass
   2. Overseeding only bare soil
   3. Applying fertilizer only on weeds
   4. Watering infrequently but heavily

   Explanation: A dense, healthy turf naturally crowds out weeds, making establishment difficult. Watering habits, spot-fertilizing weeds, and only overseeding bare patches without addressing overall turf density are less comprehensive or effective weed management strategies.