How To Read A Chemical Label

What Information Is Contained On A Chemical Label?

A chemical label contains detailed information regarding the product. The label itself is a legal document, which under legislation, must be adhered to at all times. Operating outside the instructions on the chemical label is illegal, and can result in hefty penalties, including imprisonment. It is therefore important to read the label carefully before every application, particularly for those new to farming and for those who are using a pesticide for the first time. As an example we will use a common herbicide label to highlight the important information it contains. Roundup CT (Glyphosate) is a common herbicide used everyday by people from home gardeners to farmers however, some users know very little about the product. Figure 1 shows the front page of the Roundup CT chemical label.

  • Pesticide: A chemical formulation that controls pest activity. Pesticides include herbicides (weeds), insecticides (insects), and fungicides (fungal diseases).

  • Mode of Action: All chemicals are grouped into families or classes, according to their mode of action. Mode of action classes chemicals according to the site or enzyme within a plant, disease, or insect that the active constituent works on. Mode of action is particularly important for resistance management.

  • Resistance: Within any pest population, there are individuals that are naturally resistant to the active constituent. Resistance occurs when these surviving pests are subjected to the same mode of action repeatedly; resistant hosts survive and multiply, causing a resistant population.

  • Active Constituent: The biologically active part of the chemical present in the formulation.

  • Chemical Formulation: Is a process that involves mixing the active constituent with other materials to make it suitable for use in controlling pests. Common additives to the active constituents include, emulsifiers and stabilisers.

  • Surfactant (wetter): Is a “surface active agent” which serves to lower the surface tension of the water in the spray solution. This enhances spray coverage, as a droplet with low surface tension, spreads out and covers a greater area of leaf.

  • Compatibility: The ability of a pesticide to be mixed with another without causing a reduction in activity.

  • Tank Mixing: The practice of adding two or more pesticides together to control multiple pests, with the one spray application. Compatibility is very important when you are tank mixing pesticides.

  • Plant-back Period: Some herbicides have a period of time (days, weeks or even months) which must elapse before the next crop can be planted back into the treated area. Residual herbicides can have lengthy plant-back periods for particular crops, which must be adhered to prevent crop damage.

  • Withholding Period: The period of time which must elapse between treatment of a pesticide, and the harvest, or selling of the treated product. The withholding period is there to prevent higher than acceptable pesticide residues in food products.

Roundup® CT 5, 10, 20, 55, 110, 115, 200, 400, Date: 06.07.06 Page 1 of 14
Herbicide 500, 1000 and Bulk LITRES Front Label
  Roundup® CT
Broadacre Herbicide by Monsanto
(present as the isopropylamine salt)
Water soluble herbicide for non-selective control of many annual
and perennial weeds in conservation tillage situations.
5 Litres
10 Litres
20 Litres
55 Litres
110 Litres
115 Litres
200 Litres
400 Litres
500 Litres
1000 Litres
Bulk Litres
Distributed by:
Nufarm Australia Limited
ACN 004 377 780
103-105 Pipe Road
Laverton North, Victoria 3026
Tel: (03) 9282 1000
Fax: (03) 9282 1001
APVMA Approval No 31394/ *L/0506
Batch no.:
Date of manufacture:
Figure 1: Roundup CT chemical label.

Interpreting A Chemical Label?


  • The first line indicates that Roundup CT is sold in container sizes ranging from  five litres through to 1000 litres, and even in bulk. The label was last submitted for changes on 6/7/06, and that the label contains 14 pages.

  • The CAUTION denotes the poison schedule of the pesticide, which in this particular case is a SCHEDULE 5. This means it is available to the public, but requires caution in its storage, handling and use. The SCHEDULE number also indicates the type of personal protection equipment that should be worn when using this product.

  • Roundup CT is the trade name of the pesticide, with the ACTIVE CONSTITUENT describing the biologically active part of the product. This also explains the strength of the product in grams per litre of active ingredient. This particular label tells us that the Glyphosate in Roundup CT is in the Isopropylamine salt form at strength of 450grams/litre.

  • Glyphosate products come in differing strengths, with different active salt types; therefore it is important to know what product you are using so that the rate of application can be kept equal between different products.

  • The blurb under ACTIVE CONSTITUENT explains what the product is used for, and that it is a water soluble herbicide. We will have a detailed article on chemical formulations in the future, but generally, a water soluble herbicide mixes readily with water, and stays the same colour once mixed. 

  • The next line points out that it is IMPORTANT to read the attached booklet before using the product. The booklet part of the label contains essential information on rate selection, registered pests, the requirement of surfactants (if any), plant-back periods and withholding periods. This is the most important part of the label, but also tends to be the most confusing for users.

  • Take your time to study this booklet closely, as you should understand the CRITICAL COMMENTS and RESTRAINTS that will affect the efficacy (performance) of the pesticide. Many spray failures occur as a result of users not thoroughly reading this part of the label.

  • The last few lines on the front page of the label outline who distributes the product in Australia. In this case the company is Nufarm Australia Limited. The last few lines give the company's contact details which can be used in case of an emergency, for more product information, or in case of a spray failure.

  • The Date of Manufacture is important in the event of a spray failure, as is the Batch Number. The batch number allows the company (in this case Nufarm) to trace the product. The initial point of manufacture can be traced, and if needed, the product can be retested for compliance of label specifications.

Which Parts Of The Chemical Label Do I Need To Read?

This article explains only a small portion of the entire 14 page chemical label and booklet; however it does outline the sections of the label which require particular attention. After reading RATES SELECTION, the other two important sections of the label are (1) DIRECTIONS FOR USE, and (2) GENERAL INSTRUCTIONS.

(1) The DIRECTIONS FOR USE provides important information on how to get the best results from the herbicide. Conditions that may adversely affect the efficacy of the herbicide are mentioned in this section, along with RAINFAST periods. An example of the DIRECTIONS FOR USE can be seen below.

RESTRAINTS: To ensure herbicide absorption, DO NOT disturb weeds by cultivation, sowing or grazing
for 1 day after treatment of annual weeds and 7 days for perennial weeds, except where noted.
Figure 2: Directions For use

(2) The GENERAL INSTRUCTIONS gives the most detailed product information. Below are a few of the general instructions from the Roundup CT label, with a brief summary of the information contained in each section. The Roundup CT label contains information on aerial spraying; tank mix additives; boom spraying equipment; surfactant selection; insecticide compatibility; crop establishment after application; storage and disposal options; in addition to the following instructions:

GENERAL INSTRUCTIONS Summary Of Chemical Label Information
Roundup CT is a non-volatile, non selective, water soluble liquid herbicide with non-selective herbicidal activity. It is absorbed by plant foliage and green stems and moves through the plant from the point of contact to and into the root system. Effects may not be apparent for 3–7 days (annual weeds) or 2–3 weeks (perennial weeds) or longer under cool,cloudy conditions. Product Properties, How It Works
A withholding period for grazing stock is not required. However, it is recommended that grazing of treated plants be delayed for one day after treatment of annual weeds, or 7 days of perennial weeds are present, to ensure absorption of Roundup CT. Certain plants (eg. Soursob, variegated thistle) may be naturally toxic to stock. Where known toxic plants are present, do not allow stock to graze until complete browning of treated plants has occurred. Withholding Period For Grazing
Weeds should be actively growing at the time of treatment. Do not treat weeds under poor growing or dormant conditions (such as occur in drought, water logging, disease, insect damage or following frosts) as reduced weed control may result. Reduced results may also occur when treating weeds heavily covered with dust or silt. Prior herbicide application may also induce stress in weeds. How To Get The Best Results
Rainfall occurring up to 6 hours after application may reduce effectiveness. Rainfastness or general efficacy may be reduced if weeds are not actively growing, are under stress or conditions of low light intensity/darkness. Heavy rainfall within 2 hours after
application may wash the chemical off the foliage and a repeat treatment may be required. Delay treatment of plants wet with dew or rain, if water droplets run off when plants are disturbed. Avoid contact with foliage, green stems or fruit of crops, desirable plants and trees, since severe injury or destruction may result.
Rainfast Period For The Product
Roundup CT may be tank-mixed with the following herbicides, insecticides and additives. Read and follow all label directions, restraints, plant-back periods, withholding periods, regional use restrictions and safety directions for the tank mix products.
Notes On Tank Mixing 
Ally, Associate, Avadex Xtra, Nufarm Estercide 800, Express, Flame, Garlon 600, Glean, Hammer, Invader, Nufarm Kamba 500 (dicamba), Lusta, Logran 750WG, Logran B Power (ensure fully dispersed prior to addition of Roundup CT), Lontrel, Nufarm LV Estercide 600 (2,4-D ester), Nufarm LVE MCPA (MCPA LVE), MONZA®, Nugran, Flowable Nu-trazine, Nu-trazine 900 DF (DO NOT apply this tank mix for control of Barnyard grass or Liverseed grass), Rifle, Flowable Simazine, Nufarm Simazine 900 DF, Starane 200, Stomp, Striker, Surpass 300, and TriflurX (trifluralin). Other brands have not been tested. *Spraymate Liase (Ammonium sulphate) may improve the performance of tank mixtures of Roundup CT and atrazine or simazine. See directions below.
Compatible Tank Mix Products
1. Fill the spray tank 1/3 to 1/2 full with clean water and start agitation.
2. Add Spraymate Liase where required.
3. Add recommended herbicide/insecticide/additive to the spray tank and mix thoroughly.
4. Add Roundup CT and the remaining water. Mix thoroughly.
5. Add surfactant, if required, near the end of the filling process to minimize foaming.
6. Always maintain adequate agitation during application and use the tank mix promptly.

 How To Mix The Product
Avoid contact with foliage, green stems or fruit of crops, desirable plants and trees, since severe injury or destruction may result.
DO NOT apply under weather conditions, or from spraying equipment, that may cause spray to drift onto nearby susceptible plants/crops, cropping lands or pastures.
Environmental Considerations
Do NOT contaminate dams, rivers or streams with product or used container. Do NOT apply to weeds growing in or over water. Do NOT spray across open bodies of water.
Further Environmental Considerations

Figure 3: General instructions

Who Can I Talk To About Rate And Product Selection?

A chemical label is full of useful information, but it can be a daunting document for those not familiar with it. The successful use of any chemical is reliant on understanding the product, how it works and the factors affecting its efficacy. Before a product or rate is selected, the problem pest should be correctly identified and care taken to establish its growth stage. This process should always be conducted in the paddock.

For a visual appraisal of pests most rural retailers have agronomists employed at their stores, who specialise in agricultural chemicals, and can advise on rates and product selection. Similarly, the NSW DPI has qualified agronomists along with chemical companies, who have representatives that can guide you through the chemical label and help with technical enquiries.
Farmstyle Australia also has qualified agronomists on hand to answer any questions. These questions can be sent to Ask the Experts.

Are You Interested In Finding Out More Information on Chemicals Labels?
Follow the PestGenie link to search for chemical information by product, active constituent, problem, situation or product type. 

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