||Weeds are not only a pest in the garden but can also prove a threat to our natural environment. This course will teach you how to identify weeds and the different methods that can be used to control them.
||A weed is any plant that is growing where you don't want it. A weed will compete with your desired plants for light, space, water and nutrients. A plant could also be a weed because of a particular characteristic; it could be poisonous to stock or humans, if it acts as a host plant to pests and diseases (of both other plants and/or animals), if it has damaging roots, or if it causes allergies. Any plant has the potential to be a weed.
Once you have completed this course you will:
- Know what weed you are dealing with
- Know how those varieties grow, and what conditions they do and don't tolerate
- Then create conditions which they don't like
The course is divided into 7 lessons as follows:
1. Weed Identification: review of the system of plant identification, general characteristics of the weeds, further information, contacts, etc.
2. Weed Control Methods: practical research on management of weeds, understanding terminology and the use of mulches
3. Chemical Weed Control: review of commercial and domestic herbicides, determining what differentiates them, their availability and use.
4. Weed Control In Specific Situations: understanding weed control strategies for particular situations, accessing first hand information about weed control from industry leaders and determining a weed control program for five different sites.
5. Safe Chemical Application: reviewing what types of chemicals and application methods are used in the industry and the required safety procedures for the handling and administrating chemical herbicides.
6. Non-Chemical Weed Control: determining any detrimental effects chemical herbicides have on the environment, reviewing non-chemical applications and their effectiveness.
7. Developing A Major Weed Control Program: a practical lesson where the student can fully demonstrate their understanding of weed control by devising a weed management plan for a designated area.
- To distinguish between different types of weeds, and identify common weed species, growing in your locality.
- To understand the characteristics of different weed control methods.
- To be able to explain the use of chemical herbicides to control weeds.
- To be able to specify appropriate weed control methods, for different types of situations.
- To determine appropriate techniques for the safe application of chemical herbicide in a specific situation.
- To be able to explain different non-chemical weed control methods.
- To be able to devise appropriate methods for control of weeds, for specific problems, in both the horticultural and agricultural industries
- To be able to determine a detailed weed control program for a significant weed problem.
EXAMPLES OF WHAT YOU MAY DO IN THIS COURSE
- Observe and consider over 100 different varieties of weeds and prepare plant review sheets for different weed plants.
- Make up a list of information resources.
- Plant, grow and observe different varieties of weeds.
- Make drawings of young seedlings of at least fifteen different weeds.
- Speak/interview people who have to deal with weed control in their daily life.
- Visit a nursery, garden shop or hardware store that sells herbicides to the public.
- Visit at least one supplier of herbicides for industrial and agricultural use.
- Contact larger chemical companies for leaflets on different herbicides.
- Investigate at least two workplaces where weed control programs are regularly carried out.
- Visit and inspect different sites where weeds are a problem.
- Photograph different places that have been treated with weedicides.
- Contact your local Department of Agriculture or Lands Department for researching purposes.
- Visit several farmers who raise different types of livestock.
- Develop guidelines for an integrated weed control program for a particular site
How Can Weeds be Controlled?
Before you can control a weed, you need to know what it is. When you understand it's significance (eg. where it came from, how and when it spreads, how it impacts on other plants), you are only then in a position to determine an appropriate way to control it.
The obvious way of controlling any weed, to the uninitiated, may be to poison it. This isn't always the best way. Poisons can have unforeseen consequences; and do not necessarily always do what you intended. If you are going to use a poison though; it is important that you choose an appropriate chemical and use it in an appropriate way.
This course can help you identify different weeds, understand their significance, consider options for control, and select appropriate control methods.
Weed Control Without Chemicals
Weeds can be removed by hand, mown down with a machine, smothered by mulch or killed off by introducing animals that will eat them. These are just some of many ways that you might consider controlling weeds.
Smothering Weeds with Mulch
A layer of mulch on top of weeds will do two things:
- Stop light getting to the weed (and it needs light to grow).
- Provides a physical barrier which the which the plant must break through to grow.
Vigorous weeds need a thicker or stronger mulch to stop their growth. Small weeds can be contained by a thin layer of mulch.
Most weed seedlings need at least 8 to 10 cm of mulch over the top of them to stop growth. This thickness can be reduced by mowing the weeds then covering with a thick layer of newspaper (perhaps 15 to 30 sheets thick) before laying down the mulch.
Suitable for trees & shrubs, vegetable beds, around fruit trees etc. Be sure to get mainly shavings, not sawdust. If it contains too much sawdust, it can blow away in the wind Most sawdusts rot down quickly causing a loss of nitrogen from the soil. (To compensate this loss, the plants need to be fed with extra nitrogenous fertilizer such as dynamic lifter or blood & bone. If you use wood shavings, sprinkle half a cup full of dynamic lifter at the base of
each plant on top of the shavings.
Some hardwood sawdust or shavings is slow to decompose and does not need extra fertilizer. Softwood sawdusts might decompose much faster.
You should water shavings thoroughly when first delivered to help them stabilize.
Shavings will compact after a few weeks, a 15cm layer perhaps settling to become 8 to 10cm thick.
Fresh pine bark contains toxins which can damage plants. Pine bark from reputable suppliers is composted and free of toxins. Fine pine bark controls weeds better than very coarse chunky bark. Pine bark is more expensive than shavings but most people think it looks better.
Hay or Straw
Particularly suited to vegetable gardens but also good in other places. Some types of hay or straw contain lots of weed seeds which germinate and create a weed problem.
Lucerne hay is prefered to other types because it doesn't contain weed seeds, and it is more nutritionally balanced for the plant. Lucerne hay controls most weeds if laid down as thick pads as it comes out of the bale (ie: In compact pads rather than loose).
Sugar cane mulch is excellent as well, because it does not contain seeds; but residues of sugar may attract ants. This can be an undesirable thing to have around a home garden; if the ants bite. It can be an advantage in termite prone areas, where ants are a natural enemy of termites.
There are a range of weed mat products available, usually a closely woven fabric, with holes large enough to allow water to get through but small enough to stop weeds growing through.
Controlling Weeds with Biological Controls
This involves introducing natural predators into an area to attack weeds.
It is a method which has been used occasionally with dramatic results, but which can "backfire" if the full implications of introducing something new into an environment are not understood.
Prickly Pear (a cacti which was a severe problem in the past) was brought under control in Australia by introducing a parasitic moth which has a grub that attacks the plant.
A rust (fungal) disease was introduced into Australia in the 1980's in an attempt to control blackberry weeds. Though this has had some affect, to this stage it has only been a mild deterrent.
Insects have been used to control the spread of water hyacinth in the United States and Australia.
On completion of this course.
Students will have a very good understanding of how to control a variety of weeds, the safe handling and distribution of herbicides in turf areas, parks and gardens, and other horticultural situations