Herbicide Formulations Plant Science 280 Mr. Gomes

Formulation All herbicides are formulated Liquid Solid Formulations vary for different methods of applications Selectivity To facilitate use Increase effectiveness It is a physical, not chemical mixture

Formulation Basics Chemists have two primary goals; Improve biological effectiveness Place a herbicide in a physical form that is convenient for users The chemical industry is dominated by Arysta, BASF, Bayer, Isagro, Chemtura, Dow, DuPont, FMC, NuFarm, Monsanto, Syngenta, Valent What does the global impact of merging lately mean?

Types of Formulations - Liquid Solution Concentrate Usually require little formulation and have high concentrations: Acidic Salts Emulsified Concentrate Herbicide dissolved in an organic solvent. Acts like oil and water when formulated Invert Emulsions More viscous and produce larger droplets Flowable Concentrate No organic solvent, and are insoluble in water. Encapsulated Encapsulated dry or liquid herbicide in microscopic polymer

Types of Formulations - Dry Dusts and Dry Powders Fine powder, insecticides Wettable Powders Dust like solids that easily suspended in water. Plug Granules Used as soil applied Dry Flowable and Water-Dispersible Granules Water-Soluble Packets and Effervescent Tablets Other

Surfactants and Adjuvants Surface active agent Increase wettability and spread ability Enhance Phytotoxicity and Penetration Adjuvants Promote foliar activity and absorption Safeners or protectants Buffering Agents, antifoam, drift control

Factors Affecting Herbicide Performance Sprayer Calibration Droplet size and rate Drift Windspeed and height above the ground - liquid 5 mph industry standard Can move anywhere from 5 feet to 3 miles Volatility Tendency of a chemical to vaporize Liquid to gas

Foliar Active Herbicides: Factors Spray Retention: Staying on the leaf Leaf Properties: broadleaves, grasses, etc Spray Solution: High surface tension and drop size Others: Growth stages, nodes, meristemic areas Environmental Factors Moisture: weather (rain, dry, wet, hot, cold) Temperature: hot versus cold Light: open stomate and photosynthetic rate

How Herbicides Work/Affected in Plants Foliar Absorption Absorption from Soil Translocation Metabolism

Foliar The application of a herbicide directly on the plant tissue itself Once on the leaf, most occur through Cuticular penetration Generally a highly efficient method Can be used to control specific, observable weed problems Timing can be a detriment

Absorption from Soil Advantages Include; Disadvantages Include Much more convenient Not dependent on growth stage Disadvantages Include Dilution Fixation by soil colloids Residuals

Translocation The movement of herbicides inside the plant Occurs through the Phloem and Xylem Phloem, think source to sink Maturity of the plant determines where translocation occurs Young leaves to roots, older leaves to shoot tips and meristem

Metabolism Can have a huge affect on the toxicity of the chemistry once absorbed Reduces the concentration levels Generally affects toxicity over the course of 3-8 days Newer chemistries are usually affected less by metabolism MCPA versus MCPP in Catchweed

Ideal Herbicide Ability to enter plants at various sites Ability to enter plants without local damage Ability to affect plant growth over various stages of plant development/size Ability to translocate in plants to site(s) of action Slow metabolism and/or degradation Moderate soil absorption to decrease leaching Wide weed control spectrum