herbicides for adu

Contact Herbicides

result in rapid injury/death to contacted tissue, but do not move through the plant

Systemic Herbicides

Absorbed by the plant and transported through the plant tissue to kill all parts of the plant, tend to work slower

Foliar Treatment

Sprayed directly on leaves of floating and emergent plants

Submersed Treatments

Applied as liquids or granules to the water column to achieve a target concentration

Copper herbicide

Fast acting CONTACT herbicide

Often used in potable water and irrigation systems

Lethal to some fish

Diquat Herbicide

Fast acting CONTACT herbicide

Absorbed and interferes with photosynthesis

Turbidity can inactivate it

Endothall

CONTACT herbicide

Used for large scale early season treatments

Available in amine salt for algae and plants or potassium salt for plants

Carfentrazone and Flumioxazin

CONTACT herbicide

PPO inhibitors causing cell membrane damage and necrosis

Carfentrazone: narrow spectrum, highly selective

Flumioxazin: broader spectrum

Highly sensitive to pH

2, 4-D

SYSTEMIC herbicide

Oldest herbicide in US

Auxin mimic causes plant to grow to death

Selective for Dicot

Florpyrauxifen-benzyl

SYSTEMIC herbicide

New auxin mimic that targets both monocots and dicots

Highly active at very low concentrations

Glyphosate and Imazapyr

SYSTEMIC herbicides

Only for foliar treatment

Glyphosate inhibits EPSPS enzyme and in inactivate by water and soil

Imazapyr inhibits ALS enzyme and is active in soil

Fluridone

SYSTEMIC herbicide

targets PDS enzyme and lets chlorophyll break down, causing bleaching

Very long contact time

Topramezone

SYSTEMIC herbicide

Inhibits HPPD enzyme, causes bleaching

Applied to actively growing plants, provides alternative for resistant plants

ALS (acetolactate synthase) inhibitors

Penoxsulam, Imazamox, Bispyribac-sodium

Used in combo with others to manage herbicide resistance

Activator Adjuvants

Surfactants, help herbicide break through waxy leaf cuticle

Utility Adjuvants

Reduce spray, foaming, or other handling issues

Adjuvants

Added to herbicide to modify activity or application

Impact of Thermocline on Herbicide use

When layers don’t mix, herbicides stay in upper layers and weeds in lower areas survive

Granular application are needed to overcome this

Diquat trade names

Tribune

Endothall Trade Name

Aquathol

Flumioxazin trade name

Flumigard

Glyphosate Trade Name

AquaNeat

Fluridone Trade Name

Sonar

Requirements for Herbicide Registrations

80-120 different studies over 6-10 years

Data must assess safety for human and non-target organism, as well as measure tolerance levels

What are pesticides regulated under?

FIFRA: Federal Insecticide Fungicide and Rodenticide Act

EPA: Environmental Protection Agency

Role of the EPA in herbicides

regulates them through pesticide labels

How is selectivity achieved in aquatic systems

herbicide choice, dosage, and timing to target one species among others

Concentration and Exposure Time (CET)

plants must be exposed to a lethal concentration over a specific time to be effective before the chemical dissapates

what do water conditioners do?

they bind to minerals in the water to prevent them from deactivating the herbicide

How does resistance affect treatment

plants that survive repeated exposure can cause a population to become resistant, so varying or combining the herbicide used, and maintaining a high efficacy can prevent this

How do Herbicides breakdown

some break down via photolysis, microbial action, or hydrolysis, while some bind to sediment to become inactive

Risk of Herbicides to fish

most are non-toxic since they target plant pathways, more concern for O2 depletion due to decay of vegetation, so treat in smaller areas

What is Integrated Plant Management

using multiple actions to achieve long term control, such as chemical, mechanical, and biological techniques