Range Notes 11/11/13

Vegetation manipulation chemical control
Herbicidal control of non-desirable species
An effective necessary and potentially environmentally sound method of plant control
Examples:
Advantages
Can be applied where mechanical methods cant
Broad array of application methods
Rapid control of weedy species
Rapid plant response
Rapid community response
Less time consuming and labor intensive than mechanical control
Les energy inputs than mechanical control
Advantages
Generally cheaper than mechanical control
Most herbicides are selective
Especially detrimental to most forbs
Generally maintains some degree of soil cover
If applied correctly herbicide control is generally safe and reliable
Can fit with other control methods into an integrated pest management plan
Can be used good for thinning brush/trees
Good for eradication of small stands of undesirable species
Good for spot control of some species
Disadvantages
No herbicide has proven to produce 100% satisfactory results
No seed bed prep if paired with reseeding efforts
May open up invasion niche for other species
Cost can be high
Especially on low productivity rangelands
Lack of selectivity of some herbicides
Non target plants and sites can be affected
Application windows maybe very restrictive
Does not remove dead plant material or seeds
Herbicide: A chemical that kills plants or severely disrupts normal growth process
Contact herbicide: causes local injury only to plant parts directly contacted
Trans located Herbicide: a herbicide applied to one part of a plant and is then moved or trans located to another part of the plant where the effects are produced
Site of action:where the herbicide impacts plants
ACC-ase inhibitors ( stop enzyme ACC from catalyzing so stops fatty acidy synth)
ALS inhibitors (stop enzyme ALS biosynthesis which stop s amino acidy synth
Photosynthesis inhibitors ( disrupt bio chemical reactions of photosynthesis)
Many others
Mode of Action Overall manner in which a herbicide affects a plant at the tissue or cellular level
Herbicides with the same MOA will have the same translocation and produce the same symptoms
Classification of herbicides Continued
Selective herbicide: a herbicide that kills or damages certain species or groups of species with little effects on other species
Nonselective herbicide: a herbicide that generally kills or damages all plants to which it is applied
Soil active herbicide: a herbicide that kills or damages plants when present in the soil Effects may be temporary or permanent selective or non selective
Timing
Based on the stage of “crop” or weed development
Some species are only vulnerable to herbicides at certain points in growth cycle
Depends on many factors
Classification of herbicide
Persistence of herbicide in the environment
Tolerance of target and non target species
Climate
Soil type cultural practices
Three options for timing of application
Pre-planting applications for control of annual weeds are made to an area before a crop is planted usually within a few weeks of planting
Pre-emergence applications are completed prior to emergence of crop or weeds
Post emergence applications are made after the crop or weed emerges the soil
Foliage application
Herbicide sprayed directly on foliage
Both selective and non-selective types
Dust applications
Not applicable to rangelands
Stem application
Stem or trunk treatments
Soil application ( both selective and non selective
Broadcast pellets soil injections (around stumps) soil surface applications
Inorganic herbicides
The earliest herbicides
Romans used brines of salt and ashes to sterilize lands
1896 common to use copper sulfate to kill weeds in grain fields
1906-1960 sodium arsenate were standard herbicides arsenic trioxide was used at rates of 400 to 800 pounds per acre for soil sterilization
1940’s various ammonium salts used for brush