Module 10 Flashcards
All herbicides have a similar mode-of-action and this partially explains why resistant weeds have developed in the past 30 years
False
Enhancement is
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
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
False
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
False
An antifoam agent is
A utility modifier to keep the solution in the tank from foaming
A liquid flowable is a nonvoter soluble active ingredient that is put in water so it is easier to handle than a wettable powder
True
An emulsifiable concentrate (EC) and a water soluble (WS) herbicide
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
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
False
The major reason why a herbicide is put into formulation is
So that the chemical can be of practical use by the grower
As the soil pH increase above 6.8 herbicides that should not be applied due to prolonged persistence include
Authority, Canopy and Canopy XL
According to the label for Pursuit applied at 1.44 oz/ac the rotational time is
8.5 months for corn and 4 months for alfalfa
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
False
Herbicides that are persistent and long residual are all in the same mode-of-action classification and last one year or longer
False
When using a emulsifiable concentrate herbicide formulation type
There is a high chance of vapor drift when temperatures are higher than 80F
Herbicide compatibility issues can occur when
- 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
The reason for tank mix or premixes include
- 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
In antagonistic herbicide interactions
Combined effects of herbicides on the weed is less than the summed effected of herbicides applied alone
In synergistic herbicide interactions
Combined effects of herbicide on the weed is GREATER than the summed effect of herbicide applied alone
3 reason adjutants may be added to a spray solution are
- To help in combining two different chemicals to keep them in suspension
- To help in rain fastness
- To aid in leaf penetration
Two true statements about herbicide movement in the phloem (symplastic movement)
- Herbicide moves with sugars to the youngest leaves
- Herbicide moves with sugar to the newest part of the roots
A herbicide that is translocated through the xylem (apoplectic movement) transport is
atrazine
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)
False
Very dry summer/fall conditions or very cool temperatures will increase the potential for carryover of many herbicides
True
