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PRE Herbicides Reference Manual

The Grains Research and Development Corporation of Australia has published “Soil Behavior of Pre-Emergent Herbicides in Australian Farming Systems: A Reference Manual for Agronomic Advisers” authored by Mark Congreve and John Cameron. Contents of the manual follow.


    Importance of controlling weeds

    Value of pre-emergent (PRE) herbicides

    Common objections to using PRE herbicides.

Factors Influencing Activity of PRE Herbicides.

    Interactions prior to incorporation: stubble and crop interception, photodegradation, and volatilization of herbicides

    Incorporation: required by some herbicides to prevent loss from photodegradation and volatilization

    Behavior in the soil: position of the herbicide in the soil in relation to targeted weed seed, binding ability as influenced by soil texture and soil organic matter content

    Properties affecting soil binding and availability: herbicide solubility (examples given), herbicide strength of binding to soil particles and organic matter (absorption coefficient–examples given), soil moisture which affects herbicide availability, rate of breakdown once in the soil, and persistence or how long a herbicide remains in the soil

    Soil pH

Rotational Crop Constraints or Plantback Restrictions on Herbicide Label

Crop Safety or Crop Tolerance; e.g., Metribuzin Sensitivity of Some Soybean Varieties

Key Residual Herbicides Listed by HRAC (WSSA) MOA/SOA Group are:

    Group B (2): ALS inhibitors; e.g. Imazethapyr (Pursuit), cloransulam (FirstRate)

    Group C (5,7): PSII inhibitors; e.g. metribuzin (Sencor), linuron (Lorox)

    Group E (14): PPO inhibitors; e.g. flumioxazin (Valor), saflufenacil (Sharpen)

    Group F (13): PDS or carotene inhibitors; e.g. clomazone (Command)

    Group K1 (3): Mitosis inhibitors; e.g. trifluralin (Treflan), pendimethalin (Prowl)

    Group K3 (15): VLCFA synthesis inhibition; e.g. s-metolachlor (Dual), pyroxasulfone (Zidua)

The authors provide narrative details and descriptions of all the above subjects, plus tables and figures that show examples of the herbicide characteristics that are discussed. Be aware that the trade names of some of the described herbicides are different from trade names of herbicides with the same active ingredients sold in the US. Use this link to ensure access to an up-to-date version of the manual.

Composed by Larry G. Heatherly, Oct. 2016, Thanks to Jimmy Sneed for bringing this resource to my attention.