Tank Mixes: Are They a Good Idea?
Roger Poole, TIPWG Agrochemical Liaison
In forestry, efficient pest and disease control is vital to maintaining healthy, productive plantations. With the rising costs of pesticides, fuel and labour, some may see tank mixing, combining two or more pesticides in one application, as a practical way to cut costs. However, unless the pesticide label explicitly allows it, tank mixing is both risky and illegal under Act 36 of 1947.
The Forestry South Africa (FSA) TIPWG Read the Label Standard Operating Procedure (SOP) sets out clear guidance for safe and lawful pesticide use, stressing the need to follow label instructions exactly as written.
The Legal Reality
Act 36 of 1947 governs all agricultural remedies, including pesticides. Using a pesticide in a way that differs from the label – such as unapproved tank mixing – constitutes an offence. Those found guilty may face fines, imprisonment or both, and may also be held liable for damages resulting from the off-label use.
Legal compliance is not optional. The label is the law.
The Dangers of Unapproved Tank Mixing
Beyond the legal implications, unapproved tank mixes can have serious operational, environmental and financial consequences.
• Incompatibility issues: The active ingredients and adjuvants in different products may react chemically, forming clumps or residues that block sprayers and damage equipment.
• Phytotoxicity: Unverified mixtures can burn leaves, stunt growth or destroy crops entirely.
• Reduced efficacy: Some chemical combinations cancel out each other’s effects, leading to poor pest control and encouraging resistance.
• Environmental hazards: Mixing pesticides can change how long they persist in the environment, increasing the risk of water contamination and harm to pollinators and other non-target species.
• Residue concerns: Certain mixtures can leave residues above the legal limits, threatening compliance with local and export standards.
These risks can cause significant operational losses and long-term ecological damage.
Best Practice for Safe and Legal Application
To ensure both safety and compliance, forestry professionals should:
• Always read and follow the pesticide label: it provides legally binding instructions for safe use.
• Refer to the FSA TIPWG Read the Label SOP: for guidance on approved mixing and handling practices.
• Clean tanks and equipment thoroughly: after each use to prevent cross-contamination.
• Avoid unapproved mixes entirely: if in doubt, do not mix. The legal and environmental responsibility always rests with the applicator, not the supplier or advisor.
A Safer, Smarter Approach
Tank mixing may appear cost-effective at first glance, but the long-term consequences far outweigh the short-term savings. Illegal or unapproved mixtures can result in legal penalties, ineffective pest control, environmental damage and crop loss.
By following label instructions and adhering to the industry’s best practices, forestry professionals can ensure responsible, sustainable and legally compliant pest management that protects both productivity and the environment.
For further information, consult the FSA TIPWG Read the Label SOP and relevant regulatory guidelines.