Jonathan Garner’s reaction has a pesticide chemicals reaction.
Summer is here and so are the pests, disease and weeds.
Last issue we discussed integrated pest management systems. This issue we’ll touch on pesticide chemicals.
Regardless of whether you’re using them or not, it’s likely you are, or will be, exposed to pesticides. Like it or not, they’re an important part of our industry. Toxicities can range from mild through to quite dangerous, and let’s be honest, most of us drive around with various bottles of pesticide chemicals in our vehicles.
Types
Many effective and toxic chemicals are available online nowadays, and nothing’s stopping you from buying and using them. If you’re using or planning to use ‘top shelf’ or non-retail chemicals, you should do your chemical certificate training. At the very least, you should have a solid understanding of modes of actions, hazard ratings, and the exposure risks to you and the environment.
Before you dismiss the relevance of this information, please take five minutes to read it. It never hurts to gain extra knowledge. After all, it’s why you picked up the magazine in the first place.
The word ‘pesticide’ is an umbrella term for the broad range of chemicals used within the horticulture and agriculture industries. Simply put, insecticides deal with pests like aphids, caterpillars, flies and mosquitoes. Herbicides control weeds. Fungicides control mildews, rusts, rots and so forth. Miticides control various spider mites and ticks. Bactericides control diseases like cankers, blights and scabs.
Each pesticide is made to interfere with the body of the pest or the growth of the disease in a specific way. ‘Mode of action’ is the term used to describe how a chemical harms or disrupts a pest. Mode of action is also important when it comes to managing pest resistance to a particular chemical. Essentially, if an insect or microorganism (disease) is exposed to the chemical but isn’t killed by it, the offspring of the pest can often be born with resistance to that chemical. This is the reason you must always take the full course of an antibiotic, by the way. It helps prevent the development of chemical resistance within a pest.
Different chemicals are cycled between applications or mixed with other chemicals to manage potential resistance of the pest or disease.
To give a taste of modes of action, here they are for readily available insecticide chemicals:
• Nervous system disruptors – many insecticides, like organophosphates (Chlorpyrifos), carbamates (Carbaryl),
pyrethroids (Synthetic pyrethrums) and neo nicotoids (Confidor) attack the pest’s nervous system. They either overstimulate or block nerve signals, leading to convulsions, paralysis and death.
• Growth and development interference – some insecticides, called insect growth regulators (IGRs), don’t kill immediately. Instead, they prevent the insect from moulting or reproducing. Over time, the population declines. These are popular with integrated pest management systems for managing fire ants, cockroaches and white fly in commercial gardens. Neem is also a type of IGR.
• Muscle function disruption (MFD) – some insecticides interfere with muscles directly, preventing normal movement, usually by disrupting calcium release. They’re relatively safe for mammals, but effective against caterpillars and leaf-feeding pests. Acelepryn is a well-known MFD used for curl grubs and army worms.
• Respiration inhibitors (energy blockers) – these insecticides interfere with the insect’s ability to make energy. They’re moderately hazardous to humans and very toxic to fish. Derris or vegetable dust is an example.
• Midgut disruptors – these act directly on the insect’s digestive system. Dipel (Bacillus) and Success (spinetoram) are popular chemicals in this category.
• Physical or mechanical action – these chemicals kill by physical means and are quite safe for humans. Chemicals such as pest oil, eco oil and soap sprays act to smother the pest and suffocate them. Squashing them with your fingers is an example of physical action.
Different actions
As insecticides work in different ways, fungicides also rely on modes of action. Greenkeepers and turf managers in particular need to rotate chemicals to avoid diseases developing resistance.
Pesticides are designed to be toxic. But the degree of harm they can do to us and the environment depends on the chemical’s toxicity and the frequency and duration of exposure. Years ago, when I worked at a wholesale production nursery and sprayed some seriously toxic chemicals, we had our blood tested every three months for chemical levels. Fortunately, many of the chemicals used then are no longer available.
Exposure warnings
Acute (short-term) effects occur shortly after exposure and can include headaches, nausea, dizziness, skin or eye irritation, or, in severe cases, seizures and respiratory distress.
Chronic (long-term) exposure can lead to future offspring being affected. Many horticultural pesticides are known as endocrine disruptors. These chemicals, even at low doses, may have measurable biological effects on you and your future children.
Exposure over time has also been linked to cancer, hormone disruption, fertility issues, and nervous system disorders.
In Australia, pesticide products must be registered with the Australian Pesticides and Veterinary Medicines Authority (APVMA). As part of this process, every product is given a signal heading on its label to alert users to the level of risk the chemical poses to humans if exposed or misused.
1. Caution – lowest hazard. These chemicals have the lowest level of acute toxicity. They may cause minor skin or eye irritation, or mild poisoning if swallowed in large amounts. Many home-garden products, such as ready-to-use sprays with natural pyrethrins or horticultural oils, fall into this category.
2. Poison – moderate hazard. This indicates a higher level of danger. These products can cause moderate illness if mishandled and often require gloves, long sleeves, or other protective equipment. Examples include some fungicides, herbicides, andconcentrated insecticides.
3. Dangerous poison – highest hazard. These chemicals present the most serious risk. They may cause severe poisoning, permanent injury, or death from small exposures. Labels include strong warnings and safety directions. These are rarely found in home gardens and are more common in agricultural or industrial settings. But, as mentioned earlier, these products are readily available online. If you plan to use them, please be careful and store them both correctly and safely.
Safety data sheets
Pesticide Safety Data Sheets (SDS) provide detailed information on the risks and safe handling procedures for a particular pesticide, including identification, hazards, first aid, and disposal information. SDS can be obtained from the chemical manufacturer or supplier for each pesticide in use, and they must be kept readily accessible where the product is stored and used. Key sections within an SDS detail physical and chemical properties, toxicological information, and environmental impact. These aid in risk assessments and emergency planning. By law, you must carry an SDS for every pesticide you are carrying or planning to use, and you must carry and store chemicals appropriately.
Please don’t ever decant some into soft drink bottles. It happens and it has killed people.
Be careful
Children, pets, fish, and pollinators like bees are especially sensitive to pesticides. Even small amounts can cause harm. It’s essential to understand hazard ratings and safety instructions on product labels.
Pesticides are powerful tools in the landscape toolkit, but with that power comes responsibility. It’s vital to understand how they work and their potential effects on humans and the environment. Understanding the meaning of hazard ratings and modes of action helps make informed choices.
Whenever you can, choose the least-toxic option and follow the label instructions exactly. Remember, the goal is not just to protect your plants, but also to safeguard your health, your family, and the environment in which you’re working.
