Chemical Management

7. Controls for using pesticides and herbicides

When needed retail and domestic grade pesticides and herbicides can be used in schools under the following conditions:

• there is a current safety data sheet (SDS) available for school staff using the product to review and reference
• all recommended PPE is worn in accordance with the SDS
• all instructions on the label and in the SDS are followed for use and disposal
• products are clearly and correctly labelled especially if they are if they are diluted or decanted from the original container (refer to the advice on labelling in this procedure)
• they are applied on days with little or no wind to reduce the risk of the product drifting
• students and other staff are not exposed.

Application is best scheduled for weekends or outside school hours. The ideal time is after school on Fridays, to prevent exposure to students and staff.

Commercial herbicides and pesticides used by professionals or farmers differ from retail products in concentration, pack size, and regulation. Commercial products are highly concentrated and designed for large-scale application. Commercial grade products often require licences to use. Schools are strongly encouraged to use contractors for any high-risk work instead of volunteers or school staff. For more information refer to Contractor OHS Management.

Safe application of pesticides

The target pest should be clearly identified to ensure the correct product is being used.

Types of pesticides

When selecting pesticides, it is recommended to consider the risks, effectiveness and purpose of the product to be used. This applies to retail (domestic) grade products, commercial (industrial) grade products and homemade remedies. Appropriate PPE should be worn when using homemade pesticides.

At times it may be necessary to use commercial pesticides when other measures have failed. Commercial pesticides should only be used in accordance with the label and product SDS. Schools are strongly encouraged to use contractors for the application of commercial grade pesticides.

Pesticides commonly used in school settings include the following.

Pyrethroids

Obtained from the dried flowers of some chrysanthemum species and effective against a wide range of insects, including:

• aphids
• caterpillars
• bugs.

Important: Pyrethroids are plant derivatives or synthetic analogous that may cause allergic reactions. All registered pyrethroids are safe if used according to the label and product SDS.

Garlic spray

A natural and effective way to deter many common garden pests. It is made by infusing garlic with water, often with additions like dish soap and oil to improve its effectiveness and longevity. The garlic's sulphur compounds are repellent to pests, while the oil helps the spray stick to leaves.

Effective against aphids, slugs and snails and can help deter other pests such as thrips, some beetles, and some fungal diseases.

White oil

Useful against scale, mealy bugs and aphids. Can sometimes be mixed with pyrethroids increase its effectiveness against a wide range of pests. Check the label and product SDS to determine whether this can be done.

Derris (Rotenone)

For controlling caterpillars, aphids and thrips on vegetables, vines, flowers and ornamentals. Follow the manufacturer’s instructions on the label and the product SDS.

Soap flakes spray

Occasionally useful in the control of some caterpillars and other larvae.

Note: Any pesticides registered for use in domestic premises can be safely used in schools. Some pesticides are best left to licensed pest control technicians, for example, termiticides. For information on termiticides, refer to the Protocol for use of termiticides in schools (in the Resources tab).

Where necessary, application of pesticides may occur during school hours to mitigate risks to human health, such as in response to mosquito activity where increased risk of mosquito-borne disease is evident.

Safe application of herbicides

The target weed should be clearly identified to ensure the correct product is being used.

Types of herbicides

When selecting herbicides, it is recommended to consider the risks, effectiveness and purpose of the product to be used. This applies to retail (domestic) grade products, commercial (industrial) grade products and homemade remedies. Appropriate PPE should be worn when using homemade herbicides.

At times it may be necessary to use commercial herbicides when other measures have failed. Commercial herbicides should only be used in accordance with the label and product SDS. Schools are strongly encouraged to use contractors for the application of commercial grade herbicides.

The following products use less toxic active ingredients and are often approved for organic use.

Acetic acid (horticultural vinegar, ~20%)

• Much stronger than kitchen vinegar
• Non-selective, burns down green growth quickly
• Most effective on young, annual weeds
• May need reapplication for deep-rooted perennials
• Can cause skin and eye irritation (PPE required for use)

Boiling water

• Great for cracks in pavement or between pavers
• Cheap and effective for small-scale use
• Poses risk of burns and scalds

Salt, vinegar and dish soap mixture

• Mix: 1L vinegar, 1 tbsp salt, 1 tsp dish soap
• Spray liberally on target plant
• Works on top growth but may damage soil if overused (salt can be persistent)

Iron-based herbicides

• Retail product (follow label instructions and SDS)
• Targets broadleaf weeds in lawns, safe for turf
• Low toxicity and pet-safe once dry
• Can cause skin and eye irritation (PPE required for use)

Mulching or solarisation

• Mulch such as wood chips, newspaper and cardboard blocks light and suppresses weeds naturally
• Solarisation involves covering soil with black plastic sheeting to kill weeds using sun heat. This is a good method for pre-treating garden beds

Manual weeding

• Still the safest and most selective method, especially when combined with mulching
• Use tools like weed pullers, pitch forks etc to reduce manual handling risk

Large scale spraying

For large scale agricultural spraying the principal and or their delegate must ensure that licensed operators are engaged for application of herbicides such as 2,4-D, Paraquat and Diquat. These herbicides are highly toxic, with paraquat being one of the most toxic herbicides in agriculture.

For information including registered herbicides for weeds requiring control and restricted non-schedule 7 agricultural chemicals, refer to Agriculture Victoria and Australian Pesticides and Veterinary Medicines Association.