CCA - Certified Crop Advisor Weed Identification and Control Questions and Answers 1

Question 1

A CCA is scouting a field and finds a pigweed species with smooth, hairless stems and petioles that are consistently longer than the leaf blades. Some leaves exhibit a faint, V-shaped watermark. Which of the following weeds has been identified?

Accepted Answer

Palmer amaranth (Amaranthus palmeri)

Answer

The key identifying characteristic for Palmer amaranth, which distinguishes it from similar species like waterhemp, is a petiole that is longer than the leaf blade itself. Both Palmer amaranth and waterhemp have smooth, hairless stems, whereas redroot pigweed has a hairy stem.

Question 2

A post-emergence herbicide application results in severe twisting, cupping, and epinasty (downward bending of petioles) on susceptible broadleaf weeds. These symptoms are characteristic of which herbicide mode of action group?

Accepted Answer

Synthetic auxins (Group 4)

Answer

Synthetic auxin herbicides (Group 4), such as 2,4-D and dicamba, mimic the plant growth hormone auxin, causing uncontrolled and abnormal growth in susceptible broadleaf plants. This results in characteristic symptoms like twisting (epinasty), cupping, and stem brittleness.

Question 3

A producer has confirmed glyphosate-resistant (Group 9) common waterhemp in a no-till soybean field. Which of the following represents the MOST effective and sustainable management strategy?

Accepted Answer

Implement a program using a pre-emergence residual herbicide with a different effective mode of action, followed by a timely post-emergence application of another effective mode of action.

Answer

The most effective strategy for managing herbicide-resistant weeds like waterhemp is an integrated approach that does not rely on a single mode of action. A program that starts with a pre-emergence herbicide with residual activity prevents early-season competition and reduces the number of weeds that need to be controlled post-emergence. Following up with a timely post-emergence herbicide with a different effective mode of action provides a second layer of control and helps prevent the selection of further resistance.

Question 4

What is the primary function of a non-ionic surfactant (NIS) when added to a post-emergence herbicide spray mixture?

Accepted Answer

To reduce the surface tension of spray droplets, allowing for better spreading and coverage on the leaf surface.

Answer

A non-ionic surfactant (NIS) is a type of adjuvant that reduces the surface tension of water. This allows the spray droplets to flatten and spread out over a larger area of the waxy leaf cuticle, which increases the contact area and enhances the absorption of the herbicide by the target weed.

Question 5

A grower is dealing with a heavy infestation of giant foxtail, a grass weed known for a prolonged germination window, in their cornfield. Which strategy provides the most effective, season-long control?

Accepted Answer

A layered program using a full rate of a pre-emergence residual herbicide at planting, followed by a timely post-emergence application as needed.

Answer

Giant foxtail has a long emergence period, meaning new plants can germinate and emerge throughout the early growing season. A single post-emergence application will miss later-emerging weeds. The most robust strategy is to use a pre-emergence herbicide with residual activity to control the initial flushes, followed by a post-emergence application to control any escapes or later-emerging weeds, ensuring season-long protection.

(CCA) Certified Crop Advisor Practice Test

(CCA) Certified Crop Advisor Practice Test

CCA - Certified Crop Advisor Weed Identification and Control Questions and Answers 1