Herbicide resistance and env
What two factors mainly increase herbicide resistance and which can we control?
Density and mutation rate. We can control density.
What is integrated weed management and what are its components?
The integration of multiple weed control tactics into a single management program. Chemical, mechanical, cultural, biological, prevention
Herbicides- what to know before you use them
Question 1: What is the issue identified in this article with the use of the vinegar solution?
Question 2: Why is the use of vinegar limited to certain weeds/ growth stages?
1. It is not labeled as an herbicide with cautions for how to use and is corrosive to skin and could permanently damage eyes.
2. Ex: poison ivy or bindweed would have to be sprayed every two weeks for 5 years, won’t kill perennial rhizomatous weeds.
What are at least 3 reasons you should always read the label of herbicides you are using?
Recommended use, application rate, toxicity, PPE, what to do with accidents, active ingredients, time to apply, state regulations, disposal, storage
What is weed management vs control?
Management- has a goal beyond control- understanding of what is causing problem, think emergence and prevention of reproduction to minimize competition
Control- focus on getting rid of, herbicide and tillage heavy
Where does resistance come from?
Selection and selection pressure, limited number of modes of action
Why should we use an integrated weed management approach?
Rather than one, many little hammers are more effective and don't select for adaptation and resistance like one management.
US agency refuses to examine toxicity
Question 1: Why may it be important for inert ingredients to be evaluated when looking at herbicide toxicity?
Question 2: What is the "loophole" identified in this article?
1. Can cause environmental damage a hundred times worse than active ingredients. (ex: neonicotinoids worsen bee health, inert ingredients kill them).
2. Dangerous substances are marked as inert ingredients and don’t need to be listed like PFAs and POEA.
What would the ideal forecast for rain be with a soil applied herbicide? How about a foliar applied herbicide? Explain why for each.
Soil- need to penetrate soil- rain/irrigation right after application
Foliar- no rain when sprayed at least a few days-a weed out, plus surfactants, oils
What are important factors in selecting a biological agent?
Host specificity, efficacy studies non target impacts, monitoring, IWM
What are potential ways herbicides can enter the natural environment? List at least 3
What tactics are involved in prevention? List at least 3
ID weeds, legislation, monitoring, EDRR, avoid contaminated inputs
How to manage herbicide resistant weeds in Montana video
What are some of the proposed methods of managing herbicide-resistant weeds in Montana?
Integrated management!
Weed it- more precision application
Pulse crops added for continuous cropping- cultural control to remove fallow, but water limited
Weed chipper- mechanical, camera activated chizzels cut out weeds
Harvest weed seed control, but need timing to align with weed seed production and harvest
Think rotations- winter triticale and winter pea
Residual herbicides, tank mixes, varied seeding times
Differentiate herbicide activation and herbicide deactivation. Can both occur in the same plant with the same herbicide?
Activation- Chemical alone doesn’t harm the plant- the plant changes the chemistry to make it poisonous
Deactivation- plant makes herbicide non toxic- changes chemistry
Ex: wild oat and wheat- herbicide inherently non herbicidal, makes poisonous, then wheat can make not with faster metabolism- breaks down whereas wild oat has a slower metabolism.
What are two advantages and two disadvantages in selecting a biological agent?
Adv- specific, self replicating, reasonably permanent, cost effective
Dis- slow acting, need right conditions, need stable env, possible off target effects, irreversible
How do you get rid of herbicides?
Do nothing, increase breakdown (till), cover crop(can’t till in), carbon rich soil additive(biochar), remove soil
What are the goals of cultural controls?
Examples? List at least 3
Increase competitive ability of crop/natives over weeds- better managed are less likely impacted.
density, spacing, cultivars, timing, crop rotation, cover crops, solarization, occulation
In wildlands- low disturbance, prescribed burns, timing is critical, prescribed grazing
Menalled et al 2016
What are the five tactics within the framework proposed to develop an alternative weed management program?
Recognize weeds evolve on relevant time scales
Recognize mutation probabilities relate to population sizes
Herbicide resistance is a coordinated problem- larger than single farm
Incentives needed for eco-evolutionary management
Risk analysis helps eco-evolution perspective->iwm programs
Differentiate apoplastic translocation from symplastic translocation, what does it move through? How does it move through a plant? What drives its movement?
Apoplastic- moves through the xylem- from transpiration with water, move up
Symplastic- Moves through the phoem- with sugars (sucrose), from source to sink cells. Since sugar is produced in the leaves it moves to the roots by osmosis (good for perennial rhizome herbicides)
What is the main challenge of herbicide application in aquatic systems when managing aquatic in comparison to management in terrestrial systems?
Herbicides don’t stay in one place, they disperse and move with currents. Need continued application rates over time.
Define Herbicide and herbicide resistance
Herbicide- A chemical used to control or kill a plant.
Herbicide resistance- ability of a plant to survive and reproduce after a treatment with a dose of herbicide that would normally kill.
In Orloff et al 2018, which were the most effective treatments for both field bind weed and Canada thistle? Which managements had the most research?
Integrated weed management or solarization, which had far fewer papers than herbicides.
Free points!
Free!
How are herbicides classified? List at least 3
What are the steps to revegetation?