Learn protect plants from environmental damage, pest problems, disease problems and through better landscape maintenance, ensure better plant health and garden sustainability.

Course Code: VHT002
Fee Code: CT
Duration (approx) Duration (approx) 700 hours
Qualification Certificate
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Become an Expert in Plant Health Care

There are many potential plant pests and diseases, and these vary from plant to plant and country to country. However, many plant species are affected by the same problems regardless of which country they are grown in, and the ways to resolve those problems are often the same. Of course when it comes to use of pesticides, different countries have different restrictions. But there are also many non-chemical means of controlling problems including mechanical, biological, natural, and cultural methods. In short, pest and disease control is a complex area of enquiry, and mastery of the knowledge involved takes time to learn. 

This course provides a comprehensive foundation in understanding the nature and identification of plant pests an diseases through to solutions for control and eradication.

The Certificate in Horticulture (plant protection) is a vocationally orientated course comprising both studies in both general horticulture and in plant protection. It gives you the knowledge to diagnose and treat any problems that occur in the protection of a broad range of plants. 

The Certificate in Horticulture involves the following areas of study:

  • CORE STUDIES - involves at least 350 hours, divided into 15 lessons, approx. half of the course.
  • STREAM STUDIES - a further 350 hrs of study specifically relating to plant protection

Stream Plant protection consists of

  1. Diagnosing Problems
  2. Pest & Disease Problems
  3. Nutrient & Environmental Problems
  4. Pest Collection
  5. Natural vs Chemical Controls
  6. Integrated Pest Management
  7. Application Equipment
  8. Pesticide Grouping
  9. Chemical Terminology
  10. Pesticide Timing
  11. Pesticide Dynamics
  12. Controlling Pests
  13. Controlling Diseases
  14. Controlling Pests & Diseases In Nurseries
  15. Controlling Other Factors



You CAN avoid a lot of pest problems in the garden by simply thinking in advance.

Like the old adage says, “a stitch in time saves nine”; it’s easier to prevent a problem starting than to stop it later on.
  • Avoid plants that attract pests. For example, citrus are notoriously prone to a range of pests including several types of bugs, as well as scale insects, thrips, fruit flies, weevils, caterpillars, mites and borers; all of which affect fruit production and tree health unless control measures are undertaken.
  • Use preventative sprays, and you are likely to use fewer sprays, eg. spray fruit trees at bud burst and grubs are less likely to get into your fruit.
  • Clean up. If you don’t remove the infected plants and prunings, they are likely to emerge as an even bigger problem next year.
  • Get to know the pests that are the most likely problems in your locality and modify or redevelop your garden to create environments that are less friendly to that type of pest.
  • Some pests like very wet, humid conditions. You can reduce this problem by pruning to encourage air movement, and by installing drainage in waterlogged areas.
  • Some pests will hide in organic matter on the ground (mulch). You can either turn the organic matter to disturb their nests, or remove it altogether.
  • Find out about how the pest reproduces itself and interrupt its life cycle. For example aphids and leaf hoppers have a gradual metamorphosis – they will keep growing and eating throughout their life cycle. On the other hand, moths and butterflies have a complete metamorphosis and do most of their feeding when they are caterpillars.
  • Inspect your plants frequently. If a plant is being attacked by pests, remove the problem and burn/squash/destroy it very, very fast, before it has a chance to breed.
Beware…many pests have very short lifecycles and are very fertile. One insect may lay hundreds or thousands of eggs and each one of the offspring may repeat the process within a matter of months.
Scary? …only if you don’t nip the problem in the bud…
Many gardeners have found that growing certain plants together discourages pests and improves plant growth and production, eg. marigolds are often grown with tomatoes to repel whiteflies and nematodes. There are many other beneficial plant combinations that may help to reduce pest problems.
Deterrents won’t eliminate your pest problems but they will keep the numbers of pests down to manageable levels. Deterrents include:
  • strongly scented plants to deter animal pests, eg. crushed leaves of Coleus caninus to repel cats and dogs; mint leaves to deter mice and rats
  • bird scarers, eg. shiny strips of foil or empty plastic supermarket bags hung in tree branches. Make sure that you shred the bags to prevent anything from getting inside and either suffocating or being trapped.
  • metal sheeting placed around the trunks of trees to prevent possums climbing into the branches
Many commercial fruit and vine growers use nets to protect their crops from attack by birds and possums. In a domestic garden you can also use wire nets.
Don’t overuse chemical sprays. The same chemicals that kill harmful pests can also kill beneficial insects such as Ladybirds, that feed on pests.
Birds can be both a pest and a blessing in the garden. Although some eat fruit and damage flowers, others feed on insect pests. A birdbath, a tray of bird seed and places to nest, will all encourage birds to visit your garden.


The healthiest gardens are ones where the gardener has managed to create a balance between pest damage and healthy organic growing. If you are prepared to accept some losses, you can greatly reduce your need for chemical sprays and enjoy a healthier environment.
Some pests won’t harm your plants, but can be a real menace to you and your family.
eg. European Wasps: These insects have a dangerous sting and have become a real problem in recent years. They are attracted to sugary things, so if they are present in your area, do not leave open drink containers unattended when you are outside. If you find a wasp nest on your property, contact a pest control operator to safely destroy it.
Other Pests and Prevention
Fire Ants
These have become a very real problem over the past couple of years. Although the government is attempting to eradicate them they have been discovered in many parts of Australia. They are tiny and work together to attack aggressors, making humans ill and killing small animals. If you think that you find any you should report them straight away.
Cockroaches tend to hide amongst foliage and in the cracks of trees when outdoors. If you don’t wish to have them indoors then try removing the dead fronds off palm trees, and other dead foliage to eradicate their hiding places.
Termites eat dead and decaying wood as well as houses. Although they are capable of travelling long distances underground from their nest to your home, you can eliminate any potential nest sites in your garden by removing old piles of logs, tree stumps and fallen branches. Ants are a natural enemy to termites. Some people will get too heavy handed with eliminating ants around the home; and then find they are invaded by termites: so be careful with the ant poisons.
These breed where there is a supply of still water. Check the vicinity of your garden for buckets, plant pots, watering cans and so on that may be standing upright and collecting rainwater. Empty out the water and turn them upside down, since the larvae live in the water until they hatch


Consider Viruses for instance:

Viruses are small microscopic organisms which live inside the bodies of other organisms. They are parasites and can have a wide variety of different effects on the organism they infect.

One of the most common symptoms in plants is a change of colour in leaves/and or flowers. Infected leaves frequently show light green or yellow patches (ie. a variegated effect) due to interruption of chlorophyll production...hence photosynthesis is reduced. This type of infection can cause reduction of crop yield or quality, or a general stunting of the plant.

One of the most severe effects of virus would be death, although this is not common (virus can only live in a host organism while the host is alive; if the host dies, the virus dies and hence eliminates itself). Growth patterns can be disturbed and changed by virus. In some cases stunting (mild or severe) will be the only obvious effect. In other cases, virus can cause distortion in the growth (ie. twisting, blistering or other distorted formations in leaves, stems, roots or flowers). In extreme cases, leaves can be reduced to a central midrib (ie. no leaf blade at all).

Flowering and seed production can be stopped completely by a virus. Virus can also induce leaf rolling, leaf yellowing, plant wilting, and changes to the physiological processes in the plant so that some functions of a cell's metabolism cease completely.

One or several of these symptoms might occur. Plants which are very commonly affected by serious virus problems include: gladioli, carnations, chrysanthemums, strawberry, passionfruit, daphne and tulip. There are others, but you should watch these in particular.

There are many ways of detecting virus. Some are outlined below:

  • One of the earliest widely used techniques is by examination and
    comparing symptoms produced by viruses in their host plants. This
    includes symptoms both on the original host and on a range of selected
    indicator hosts. A range of plants may be grown specifically for this
    purpose (to be infected with a suspected virus and observed). Usually
    symptoms can be seen about 2 weeks after inoculation.
  • The use of an Electron Microscope has enabled viruses to be actually
    seen. Using this technique viruses fall into groups based on size and
    shape...infected plants can be checked very quickly this way. Depending
    on the size and shape of viruses seen, some idea of the identity can be
    obtained...further checks can be made using other techniques.

Viruses are not as easy to control as most other diseases. Once a plant cell is infected with a virus, the only way to eradicate the virus is by killing that plant cell. In the case of virus, generally speaking, prevention is the only cure.

  • If a plant is infected with virus..remove and burn the plant.
  • Make sure (when dealing with plants which are very susceptible to
    virus) that you always start out with "clean stock".
  • Control insects (aphis in particular)...virus are carried from one
    plant to another by insects (among other things). Fungi and nematodes
    have also been known to spread virus.
  • Use plant varieties which are more tolerant to virus (if you have a choice).
Through this course, you will develop a systemic understanding of both plants, and the threats to plants.
This is the key to plant protection. 
When you have an ability to identify the plant species you are dealing with; you then have a starting points; and will be able to systematically consider the type of problem you are looking at; gradually narrowing down the possible options; until you can make a good diagnosis then proceed with an appropriate response.


Start with the Rose Family


No course will automatically get you a job – however there are a set of parameters that will certainly help you along the way to getting work – this includes more than study:

Firstly the course you undertake has to fit with industry needs. It should also be broad enough to make you an attractive employee (to a range of employers) so the focus should not be too narrow. The same applies if you are going to set up your own farm or business; business changes all the time, consumer demand changes too so doing a course that allows you to change your approach, as needed, will help ensure your success.

Secondly the course you undertake should not only develop your knowledge but also your ability to retain and recall that knowledge, now and far into the future. Learning to problem solve (an integral part of all ACS courses) helps you to remember what you are learning. When you learn by rote or by just reading and regurgitating texts you usually do not retain that knowledge for long. ACS’s PBL system (Problem Based Learning) means that in your set tasks and assignments you are solving problems that you will also face when working in industry. It is a known method for knowledge retention too and apart from that employers value employees that show initiative and problem solving skills. This skill stands you apart from others in interviews too.

Although doing a course may not guarantee you a job – it will set you apart from those that have not studied at all and it will improve your personal choices when applying for jobs. Each job listed usually gets a huge amount of response – when employers choose people to interview they will look at a range of factors – what you have studied will be just one of those factors. You need to be able to catch a potential employer’s attention – stand out from the rest.


What else do employers look for?

  • Great communication skills: verbal, written and also the ability to use a computer.
  • Problem solving skills: thinking on your feet and working through problems in an orderly way.
  • Efficiency: doing things in a logical order without compromising accuracy improves efficiency.
  • Knowledge and skills demanded of the job.
  • A passion for the work and willingness to learn.
  • Presentation and grooming - people who present as being well organised and well-groomed will impress


What Can You do to Improve Your Career Prospects?

Passion – those that are passionate about their work and are also open to learning new things do well.

Do a course that is expansive and covers a range of subjects – this gives you greater flexibility in finding work and getting ahead. Keep learning – doing a course isn’t the end of the road, today we all have to keep learning over our working life in order to keep up with ever-changing needs and technology.

Know what is going on in your chosen industry; employers are always impressed if you can demonstrate current industry knowledge, it also means in business that you can keep up with the latest trends.

Networking with others in the industry is just one way of doing this, attending industry meetings, seminars, trade shows etc., is another. Be multi-skilled – people that are multi-skilled will catch the eye of their employer and will also do better in business. Recognise where your weaknesses lie and work on improving those.

Make sure you have a current and well-written, concise CV (resume).Tutors at this school will help our students with their C.V.'s if you ask -no cost. Resume Writing services can also be used, but they charge!

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Member of Study Gold Coast

Recognised since 1999 by IARC

Course Contributors

The following academics were involved in the development and/or updating of this course.

John Mason (Horticulturist)

Parks Manager, Nurseryman, Landscape Designer, Garden Writer and Consultant.
Over 40 years experience; working in Victoria, Queensland and the UK.
He is one of the most widely published garden writers in the world; author of more than 70 books and edito

Dr. Lynette Morgan (Crops)

Lyn has a broad expertise in horticulture and crop production. Her first job was on a mushroom farm, and at university she undertook a major project studying tomatoes. She has studied nursery production and written books on hydroponic production of herbs.

Bob James (Horticulturist)

Bob has over 50 years of experience in horticulture across both production sectors (Crops and nursery) and amenity sectors of the industry.
He holds a Diploma in Agriculture and Degree in Horticulture from the University of Queensland; as well as a Maste

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