Module 10

Question 1

All herbicides have a similar mode-of-action and this partially explains why resistant weeds have developed in the past 30 years

Answer 1

False

Question 2

Enhancement is

Answer 2

When a nonphytotoxic chemical is mixed with an active ingredient and the response to the active ingredient is greater than if used without the nonphytotoxic chemical

Question 3

A premix of two herbicides, no matter the amount of each herbicidal active ingredient is always marketed under the same trade name, although the number designation on the label may differ. For example, 60 vs 75 or 4E vs 6E

Answer 3

False

Question 4

Symptoms of contact herbicide application damage to a plant is when the outer edges of the oldest leaves are dead but the new leaves are undamaged

Answer 4

False

Question 5

An antifoam agent is

Answer 5

A utility modifier to keep the solution in the tank from foaming

Question 6

A liquid flowable is a nonvoter soluble active ingredient that is put in water so it is easier to handle than a wettable powder

Answer 6

True

Question 7

An emulsifiable concentrate (EC) and a water soluble (WS) herbicide

Answer 7

The water soluble is polar compound making it soluble in water, whereas the EC chemical is NOT water soluble but is soluble in non polar compounds like oils

Question 8

All chemicals in a formulation no matter if they are active ingredient or inert substances (that will not be phytotoxic) have to be listed in order of amount (from most to least) on the herbicide label

Answer 8

False

Question 9

The major reason why a herbicide is put into formulation is

Answer 9

So that the chemical can be of practical use by the grower

Question 10

As the soil pH increase above 6.8 herbicides that should not be applied due to prolonged persistence include

Answer 10

Authority, Canopy and Canopy XL

Question 11

According to the label for Pursuit applied at 1.44 oz/ac the rotational time is

Answer 11

8.5 months for corn and 4 months for alfalfa

Question 12

Applying a preemergent persistent herbicide is always an advantage to keep the crop weed free during the most critical time when yield loss potentials are high

Answer 12

False

Question 13

Herbicides that are persistent and long residual are all in the same mode-of-action classification and last one year or longer

Answer 13

False

Question 14

When using a emulsifiable concentrate herbicide formulation type

Answer 14

There is a high chance of vapor drift when temperatures are higher than 80F

Question 15

Herbicide compatibility issues can occur when

Answer 15

• Agitation is insufficient
• Hard water (water containing a lot of minerals) is used for mixing herbicides
• Two herbicides are mixed in the wrong order. For example, adding an emulsifiable concentrate to the spray tank before suspending a wettable power

Question 16

The reason for tank mix or premixes include

Answer 16

• Control a wide spectrum of weeds with a single application
• If the herbicides are synergistic mix, the rate of application may be decreased
• Save energy by reducing trips over a field
• Increase producer efficiency

Question 17

In antagonistic herbicide interactions

Answer 17

Combined effects of herbicides on the weed is less than the summed effected of herbicides applied alone

Question 18

In synergistic herbicide interactions

Answer 18

Combined effects of herbicide on the weed is GREATER than the summed effect of herbicide applied alone

Question 19

3 reason adjutants may be added to a spray solution are

Answer 19

• To help in combining two different chemicals to keep them in suspension
• To help in rain fastness
• To aid in leaf penetration

Question 20

Two true statements about herbicide movement in the phloem (symplastic movement)

Answer 20

• Herbicide moves with sugars to the youngest leaves

- Herbicide moves with sugar to the newest part of the roots

Question 21

A herbicide that is translocated through the xylem (apoplectic movement) transport is

Answer 21

atrazine

Question 22

All herbicides can be translocated in the plant trough the phloem (which translocates sugars from the leaves to active growing points) or in the xylem (which translocates water and nutrients from the roots)

Answer 22

False

Question 23

Very dry summer/fall conditions or very cool temperatures will increase the potential for carryover of many herbicides

Answer 23

True