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Understanding Herbicides – A Short Course for People Using Herbicides

November 28 - November 30

Understanding Herbicides

A Short Course for People Using Herbicides

Time of Course and Venue:
The course is held at Massey University in Palmerston North, and it runs for 3 days (including
a test on the final afternoon), with study material sent out to participants several weeks in
advance to allow for preparation for the course. It will be run on two occasions in 2017:
Tuesday 25 July to Thursday 27 July 2017 or
Tuesday 28 November to Thursday 30 November 2017.
Paper Coordinator: Dr Kerry C Harrington
Institute of Agriculture and Environment
Massey University
Private Bag 11-222
Palmerston North 4442
Phone: (06) 350-4926
E-mail: K.Harrington@massey.ac.nz
Aim: This course is designed primarily as a stand-alone course to give participants a good
grounding in the principles of using herbicides to control weeds. It has been designed to
prepare participants for working in the herbicide industry within New Zealand.
Learning Outcome: On successful completion a participant should be able to understand herbicides well
enough to be able to select the most appropriate compound for any weed situation and
obtain maximum effectiveness from that herbicide without causing damage to crop
Credits: All successful participants will receive an official certificate of completion and the
material will count as 5-credits at 300-level towards a university qualification.
Course Outline:
Topic 1 – Introduction:
Explanation of various things about the course; introduce participants to various terminology
about herbicides in case they know nothing; herbicide mode of action.
Topic 2 – Herbicide toxicity and legislation:
Safety testing of herbicides; relative toxicity of herbicides; New Zealand legislation;
withholding periods; the GROWSAFE scheme; the 2,4,5-T controversy; herbicide residues in
Topic 3 – Herbicide formulation:
Solutions; emulsions; wettable powders; granules; dusts; surfactants; chemical drift through
the air; common and trade names; calculations.
Topic 4 – Behaviour of herbicides in plants:
Interception and uptake of foliage-applied herbicides; availability and uptake of soil-applied
herbicides; transport of herbicides in the plant; factors affecting these processes; herbicide
Topic 5 – Behaviour of herbicides in the soil:
Adsorption; volatilization; leaching; photochemical degradation; chemical decomposition;
microbial decomposition; rates of degradation of herbicides; bioassays; activity of soil-applied
herbicides; selectivity of soil-applied herbicides; effects of weather on herbicides.
Topic 6 – Herbicide application:
Conventional spraying equipment; calibration of a sprayer; back-pack sprayers; problems with
conventional sprayers; improvements in spraying equipment; wiper applicators.
Topic 7 – Knockdown herbicides:
Characteristics of importance in decision making; broad-spectrum herbicides; translocated
knockdown of dicots in grass crops; contact knockdown of dicots in grass crops; selective
knockdown of grasses in dicot crops; sulfonylureas; other knockdown herbicides.
Topic 8 – Residual herbicides:
Residual herbicides used primarily for non-selective control; herbicides used primarily for
depth protection; selective residual herbicides which primarily control dicots; selective
residual herbicides which primarily control grasses.
Topic 9 – Economics of weed control:
When weeds reduce yields through competition; when weeds exert indirect effects in pasture;
when weeds cause other effects difficult to measure; how most weed control decisions are
Topic 10 – Weed control in pastures and lucerne:
Problems caused by weeds; keeping pastures competitive; discouraging weeds that establish;
weed control in new pastures; weed control in established pastures; control of specific
problem weeds; clearing scrub weeds; weed control in lucerne using management; weed
control in lucerne using herbicides.
Topic 11 – Weed control in annual crops:
Obtaining weed control information; cereals; maize and sweet-corn; forage brassicas; fodder
beet; peas.
Topic 12 – Herbicide resistance:
Sexual vs vegetative reproduction; advantage of genetic variability; development of ecotypes;
development of herbicide resistance; rate of herbicide resistance development; using herbicide
resistance; examples of herbicide resistance problems in New Zealand.
Cost: $1400 + GST (includes study guide, 3 days of lectures, morning and afternoon tea
and lunches, venue hire at Massey University)
Participants should arrange their own accommodation in Palmerston North. The course
begins 8.30 am Tuesday, but is finished by 3.00 pm Thursday which should allow participants
to travel home that day.
Registration: To register, please contact K.Harrington@massey.ac.nz before
25 th May for the July course and 28 th September for the November
course. Each course may not proceed if insufficient registrations are
received by that date.


November 28
November 30


Massey University