NEWS & VIEWS • MARCH 2025 23 In the forestry industry, efficient pest and disease management is crucial for maintaining healthy plantations. Given the high costs associated with pesticide applications, some may consider tank mixing multiple products as a cost-effective solution for reducing diesel and labour costs. However, unless explicitly permitted by the pesticide label, mixing two or more pesticides is not only risky but also illegal under Act 36 of 1947. The Forestry South Africa (FSA) TIPWG Read the Label SOP provides clear guidelines on the legal and practical considerations for pesticide use, emphasising the importance of adhering strictly to label instructions. The Legal Implications Act 36 of 1947 strictly regulates the use of agricultural remedies, including pesticides. According to this legislation, using a pesticide in a manner not specified on its label constitutes an illegal act. If the label does not explicitly allow for tank mixing, doing so could result in severe legal consequences, including fines, jail time or both as well as potential liability for any damage resulting from the off-label tank mixing. Potential Risks of Unapproved Tank Mixing Beyond legal concerns, unregistered tank mixes can have severe practical implications: • Incompatibility Issues Pesticide formulations contain active ingredients and adjuvants that may not be chemically compatible with one another. When mixed, they can form precipitates, reduce efficacy or even create hazardous reactions that clog sprayers and damage equipment. • Phytotoxicity Combining pesticides without proper testing can lead to phytotoxic effects, where the chemical mixture causes damage to plant tissues. This can result in leaf burn, stunted growth or complete crop failure. • Reduced Efficacy Some chemical combinations may neutralise or reduce the effectiveness of one or both pesticides, leading to inadequate pest control. This can increase the likelihood of resistance development, ultimately making pest management more challenging and expensive in the long run. • Environmental Hazards Unregistered tank mixes may alter the degradation rate (half-life) of the pesticides involved, increasing the risk of unintended environmental contamination. This could harm non-target organisms, pollinators and water sources, further exacerbating the impact on the ecosystem. • Residue Concerns Certain mixtures can result in prolonged residue persistence, exceeding maximum residue limits (MRLs) and rendering harvested timber or crops non-compliant with regulatory and export requirements. Best Practices To ensure compliance and responsible pesticide use: • Always read the pesticide label and follow its instructions to ensure the correct application instructions are carried out. • Consult the FSA TIPWG Read the Label SOP for best practices and legal guidance. • Monitor application equipment and thoroughly clean tanks after each use to avoid crosscontamination. • If in doubt, don’t do it! Remember ultimate responsibility lies with the forester, farmer or contractor applying the products, and not the company supplying them or the paid expert providing advice on them. Conclusion While tank mixing might appear to be an economically beneficial practice, the risks far outweigh the perceived advantages. Unregistered pesticide combinations can lead to legal repercussions, reduced efficacy, environmental harm and severe crop damage. By adhering to industry’s best practices and legal requirements, forestry professionals can ensure sustainable and effective pest management without compromising safety, productivity or compliance. For further information, refer to the FSA TIPWG Read the Label SOP and consult relevant regulatory guidelines. Tank Mixes : Are they a good idea? By Roger Poole, TIPWG Agro-Chemical Liaison
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