Chemical Treatments

• What types of chemical treatments are there?

• Why are chemical treatments used?

• How are chemical treatments applied?

• What are the effects of chemical treatments?

Chemical Treatments

• Types of Chemical Treatment– Pesticides

• Herbicides• Insecticides

– FertilizersCredit: florida stateparks.org

Credit: uregin.ca

Chemical Treatments

• Herbicide Use– Last option in wildlife management

• Manipulate vegetation– Favor desired plant species– Reduce undesirable species

Credit: flickr.com

Chemical Treatments

• Herbicide Use– An alternative for

• Manipulating plant succession• Altering habitat structure• Controlling unwanted plants• Preventing invasion by woody plants• Maintaining openings• Top-killing strong sprouters

– Often used in conjunction with other methods

Chemical Treatments

• Herbicide Use– Advantages

• Can be used in difficult terrain• Variety of application methods• Provides a rapid control method• Has low labor and fuel requirements• Selective types available• Can maintain grass and litter cover

– Does not expose soil– Reduced erosion

• Can be safe and reliable if done properly

Chemical Treatments

• Herbicide Use– Disadvantages

• May not control some noxious species• Careless use hazardous• Lack of selectivity in some cases• Decrease plant diversity• Often drastically reduces forbs• Can have direct and indirect effects on wildlife and habitat

Chemical Treatments

• Kinds of Herbicides– Foliar-active

• Applied directly to leaves and stems– Liquids and soluble powders

– Contact (often less selective)– Translocated/systemic (often more selective)

» Photosynthetic activity important

- Low light and soil moisture, and high temps a problem

Credit: forestryimages.org

Chemical Treatments

• Kinds of Herbicides– Soil-active

• Applied to soil surface– Liquids or pellets

– Sterilant (contact; often less selective)– Translocated/systemic (often more selective)

• Precipitation important to get to root zone

Credit: agweb.com

Chemical Treatments

• Kinds of Herbicides– Hexazinone (e.g., Velpar): Soil*/Trans

• Non-selective; some selective for conifers

– Imazapyr (e.g., Arsenal): Soil & Foliar/Trans• Conifers resistant

– Glyphosate (e.g., Round-up): Foliar/Trans• Non-selective

– Triclopyr (e.g., Garlon): Foliar/Trans• Most grasses resistant

Chemical Treatments

• Kinds of Herbicides– Piclorum (e.g., Tordon): Foliar/Trans

• Woody plants and broadleaved (forb) weed control

– 2-4-D (e.g., Relay): Foliar/Trans*• Most grasses resistant; kills forbs

– Glufosinate (e.g., Liberty): Foliar/Contact• Non-selective; kills forbs; some crop resistance

– Paraquat: Foliar/Contact• Non-selective

Chemical Treatments

• Herbicide Specificity and Effectiveness– Tuned to targets

• Grass• Broadleaves (herbaceous and woody)

– Genus/species

• Forbs often most severely effected non-target type

Credit: fipr.state.fl.usCredit: forestryimages.org

Chemical Treatments

• Herbicide Specificity and Effectiveness– Stage of plant development– Season– Soil temperature– Precipitation and soil moisture

Chemical Treatments

• Herbicide Application– Aerial

• Fixed wing or rotary wing aircraft– Spray– Pellets

• Rapid application • Large areas• Remote areas• Rough terrain

• UnselectiveCredit: mainemark.com Credit: mainemark.com

Chemical Treatments

• Herbicide Application– Ground

• Tractor-mounted• Hand applied

– Spray– Pellets

• Selective targets• Small areas

• Intensive

Credit: co.uintah.ut.us

Credit: co.uintah.ut.us

Chemical Treatments

• Short- and Long-Term Herbicide Effects– Persistence in the environment

• Herbicide longevity and residue

“…that quantity of a herbicide remaining in or on the soil, plant parts, animal tissues, whole organisms, and surfaces”

Chemical Treatments

• Short- and Long-Term Herbicide Effects– Persistence in the environment

• Herbicide longevity and residue– Negative connotations– Degree of persistence needed

Ideally herbicides persist long enough to have the effect and then dissipate quickly and completely

Chemical Treatments• Short- and Long-Term Herbicide Effects

– Persistence in the environment• Herbicide longevity and residue

– Chemical attributes

– Concentration applied

– Soil characteristics

– Climate

• Generally, increased temperature and soil microflora, organic matter, and moisture accelerates herbicide degradation; leaching effects

• Soil applied (v. foliar) usually persist longer

Case study: Tebuthiuron (soil applied) found 11 years later

Chemical Treatments

• Short- and Long-Term Herbicide Effects– Direct wildlife impacts

• Mortality– Generally less toxic than insecticides– Usually do not biomagnify

• Case studies– Trifluralin

» LD50 at normal applications for mallard embryos– Paraquat

» High rates of mortality for mallard embryos at ½ recommended application rate

Chemical Treatments

• Short- and Long-Term Herbicide Effects– Indirect wildlife effects

• Vegetation Structure and Composition• Food and Cover

– Increase abundance and diversity» Dominant plant- exotic, invasive» Shrub invasion

Credit: smslrwma.org

Chemical Treatments

• Short- and Long-Term Herbicide Effects– Indirect wildlife effects

• Vegetation Structure and Composition• Food and Cover

– Decrease abundance and diversity» Forb Suppression

Credit: invasiveplants.ab.ca

Chemical Treatments

• Herbicide Use– Balance pros and cons

• Reduced use during the past 50 years• Some banned

Chemical Treatments

• Insecticide Use– Control insect pests

• Plants• Livestock

Credit: forestryimages.org Credit: forestryimages.org

Chemical Treatments

• Kinds of Insecticides– Chlorinated hydrocarbons

• DDT, Aldrin, Dieldrin

– Organophosphates• Malathion, Parathion

– Carbamates• Fenoxycarb

– Pyrethrins

Chemical Treatments

• Kinds of Insecticides– Attack central nervous system– Highly toxic– Persist in environment

• Insecticide Application– Aerial – Ground

Credit: newswire.com

Credit: birdie.com

Chemical Treatments

• Short- and Long-Term Insecticide Effects– Direct wildlife impacts

• Mortality– Primary poisoning– Secondary poisoning– Biomagnify

• Endocrine Disruption– DDT

• Aquatic Systems

Credit: friends of blackwater.org

Credit: scienceclarified.org

Chemical Treatments

• Short- and Long-Term Insecticide Effects– Indirect effects

• Food– Decrease abundance and diversity

» Arthropod losses

» Case of upland game birds

Credit:eveanderson.com

Chemical Treatments

• Fertilizer Use– Permit plant establishment– Alter plant composition– Increase nutrients available to plants– Increase palatability of forage

– Soil tests required• pH important

Chemical Treatments

• Kinds of Fertilizer– Soil

• Absorbed through roots

– Foliar• Absorbed through leaves

Chemical Treatments

• Kinds of Fertilizer– Combinations of

• Nitrogen (N), Phosphorus (P)*, and Potassium (K)

– Secondary nutrients• Calcium, sulfur, magnesium

– Micronutrients• Boron, chlorine, manganese, iron, …

– Organic or Inorganic– Natural or manmade

Credit: grow.ars-informatica.ca

Credit: grow.ars-informatica.ca

Chemical Treatments

• Fertilizer Application– Aerial– Ground

– Season

Credit: forestryimages.org

Credit: columbiabasinhelicopters.com

Chemical Treatments

• Fertilizer Effectiveness– Grasses, shrubs, and forbs

• N

– Legumes• P• N possibly as seedlings• Sulfur

– Care not to depress legumes• Grass:legume ratio in grasslands

– NCredit: forestryimages.org

Credit: forestryimages.org

Chemical Treatments

• Short- and Long-Term Fertilizer Effects– Direct wildlife impacts

• Mortality– Low– Pellet form = grit

Chemical Treatments

• Short- and Long-Term Fertilizer Effects– Indirect wildlife impacts

• Vegetation structure and composition– Food and Cover

» Increase quantity and quality» Decrease diversity

• Aquatic (and some terrestrial) systems and eutrophication (N and P)

Chemical Treatments

• Chemical Treatments– Types– Why they are used– How they are applied– Effects