Active ingredients A–Z
41 reference monographs. These explain the chemistry; the registered label of the specific product always governs legal use.
Glyphosate
Herbicide
Glycine (HRAC Group 9 — EPSPS inhibitor)
- Mode of action
- Systemic, non-selective. Inhibits the EPSPS enzyme in the shikimic-acid pathway, blocking aromatic amino-acid synthesis. Absorbed through green tissue and translocated to roots and meristems; plants yellow and die over 7–21 days.
- Uses
- Total weed control in minimum-till cropping, orchards, vineyards, fence lines, roadsides, industrial sites and aquatic margins (registered formulations). The single most-tendered herbicide in South African, Namibian and Botswanan municipal and roads contracts, typically specified as 360 g/l SL or 540 g/l SL in 20L packs.
- Crops & targets
- Annual and perennial grasses and broadleaf weeds; no soil residual activity.
- Safety
- Low acute mammalian toxicity but formulations with tallow-amine surfactants are more hazardous — use crop-safe formulations near water. Avoid drift onto desirable plants. Resistance documented in rigid ryegrass and hairy fleabane in SA — rotate modes of action.
- Field notes
- Hard water antagonises glyphosate; condition spray water with ammonium sulphate (Amsul-50, Hyperboost) for full efficacy. Rainfast within ~6 hours with quality formulations.
2,4-D
Herbicide
Phenoxy-carboxylic acid (HRAC Group 4 — synthetic auxin)
- Mode of action
- Selective systemic. Mimics indole-acetic acid, causing uncontrolled growth, stem twisting and death in susceptible broadleaf plants. Grasses are tolerant.
- Uses
- Broadleaf weed control in lawns, sports turf, pastures, maize, wheat and sugarcane. A staple of municipal turf-care tenders, frequently specified with MCPA and dicamba in 5L packs.
- Crops & targets
- Broadleaf weeds (dandelion, plantain, khaki weed, thistles) in grass crops and turf.
- Safety
- Highly volatile ester formulations can drift and damage tomatoes, vines, citrus and cotton — use amine or low-volatile formulations near sensitive crops.
- Field notes
- Do not use the same spray equipment for hormone-type herbicides and sensitive broadleaf crops without rigorous decontamination (Flushall).
MCPA
Herbicide
Phenoxy-carboxylic acid (HRAC Group 4 — synthetic auxin)
- Mode of action
- Synthetic auxin, similar to 2,4-D but gentler on cereals and turf; systemic and selective.
- Uses
- Broadleaf weed control in wheat, oats, barley, pastures and fine turf. Common in tender turf-mix specifications (MCPA + dicamba + 2,4-D).
- Crops & targets
- Broadleaf weeds in cereals and turf; safe on most grasses.
- Safety
- Moderate persistence in soil; observe grazing withholding periods on treated pastures.
- Field notes
- Often sold as 400 g/l dimethylamine salt; mixes well with dicamba for woody broadleaf weeds.
Dicamba
Herbicide
Benzoic acid (HRAC Group 4 — synthetic auxin)
- Mode of action
- Systemic auxin mimic with strong activity on woody and deep-rooted broadleaf weeds.
- Uses
- Turf, maize and pasture broadleaf control; brush suppression in mixtures. Tender turf mixes frequently pair dicamba with MCPA and 2,4-D.
- Crops & targets
- Hard-to-kill broadleaf weeds, bramble and woody regrowth.
- Safety
- Volatile and drift-prone; buffer zones near sensitive broadleaf crops are essential.
- Field notes
- Garden Route / George municipal tender specifications repeatedly list an MCPA+dicamba+2,4-D combination in 5L for turf.
Simazine
Herbicide
Triazine (HRAC Group 5 — photosystem II inhibitor)
- Mode of action
- Root-absorbed, residual. Blocks electron transport in photosystem II, starving emerged and germinating weeds.
- Uses
- Long-residual bareground control on roadsides, railways, substations and industrial yards; also registered in maize, orchards and vineyards. 500 SC in 20L is a recurring roads-department tender item.
- Crops & targets
- Germinating annual grasses and broadleaf weeds; residual 6–12 months on soil.
- Safety
- Leaches in sandy soils — keep away from boreholes and watercourses; rotational crop restrictions apply.
- Field notes
- Combine with glyphosate for knockdown-plus-residual vegetation contracts.
Imazapyr
Herbicide
Imidazolinone (HRAC Group 2 — ALS inhibitor)
- Mode of action
- Systemic ALS-inhibitor absorbed by roots and foliage; residual in soil for many months.
- Uses
- Total vegetation control on non-crop land, firebreaks, powerline servitudes; cut-stump and soil treatment of invasive bush (prosopis, acacia) — a key Namibian bush-encroachment tender active.
- Crops & targets
- Woody species, grasses and broadleaf weeds on non-crop areas.
- Safety
- Long soil residual — never use where desirable vegetation roots may extend; groundwater caution on sandy soils.
- Field notes
- Typically supplied as 250 g/l SL (Outpace Super and equivalents) in 5L/20L/25L.
Glufosinate
Herbicide
Phosphinic acid (HRAC Group 10 — glutamine synthetase inhibitor)
- Mode of action
- Contact, partially systemic. Causes ammonia accumulation and rapid photosynthetic disruption.
- Uses
- Non-selective weed control in orchards, vineyards and fallow; the leading glyphosate rotation partner for resistance management. Tendered as 200/280 g/l SL.
- Crops & targets
- Annual weeds; weaker on perennials than glyphosate.
- Safety
- Higher acute toxicity than glyphosate — full PPE (gloves, respirator) required when mixing.
- Field notes
- Works best in warm, humid conditions with good coverage; add a wetter (Wetcit Duo, Charge).
Triclopyr
Herbicide
Pyridine-carboxylic acid (HRAC Group 4 — synthetic auxin)
- Mode of action
- Systemic auxin mimic particularly effective on woody plants; translocates to roots.
- Uses
- Brush and invasive tree control (black wattle, prosopis, lantana) by foliar spray, cut-stump or basal-bark application with mineral oil carrier (Actipron Super). Gel formulations (triclopyr+picloram, Kaput-type) are standard for targeted cut-stump work.
- Crops & targets
- Woody weeds, bramble, invasive acacia and eucalyptus regrowth.
- Safety
- Butoxyethyl ester is for non-crop use; amine salt has wider crop registration. Avoid drift to broadleaf crops.
- Field notes
- 480 g/l EC in 1L/5L/20L; ester form is rainfast within hours.
Picloram
Herbicide
Pyridine-carboxylic acid (HRAC Group 4 — synthetic auxin)
- Mode of action
- Potent, residual auxin mimic — among the most persistent pyridine herbicides.
- Uses
- Deep-rooted woody weed and bush control, often co-formulated with fluroxypyr (ME) or triclopyr (gel). Namibian and Botswanan bush-encroachment programmes specify picloram mixtures for prosopis and dichrostachys.
- Crops & targets
- Woody invasive species; do not use near desirable trees or gardens.
- Safety
- Soil residual can exceed 12 months; manure from animals grazing treated forage can damage sensitive crops.
- Field notes
- Kaput-type gel (triclopyr 120 + picloram 120) applied to freshly cut stumps gives near-100% kill with minimal environmental loading.
Tebuthiuron
Herbicide / Arboricide
Substituted urea (HRAC Group 5 — photosystem II inhibitor)
- Mode of action
- Soil-applied, root-absorbed PSII inhibitor; slow, thorough kill of woody plants over 6–24 months.
- Uses
- The backbone of Namibian bush-encroachment tenders: granular (200 g/kg GG) applied to soil around target shrubs (acacia mellifera, terminalia, dichrostachys) to restore grassland. Also used on fence lines and firebreaks.
- Crops & targets
- Encroaching bush species; grass cover recovers after shrub death.
- Safety
- Very persistent and mobile — keep well away from desirable trees, watercourses and boreholes. Non-crop use only.
- Field notes
- Limpopo 200 GG (25 kg) is the reference product; application rates vary by species and soil — follow label tables.
Bromacil
Herbicide
Uracil (HRAC Group 5 — photosystem II inhibitor)
- Mode of action
- Root-absorbed residual PSII inhibitor for total soil sterilisation.
- Uses
- Railways, road shoulders, substations, tank farms — anywhere total bareground is specified. Frequent tender item as 250 SC or 80 WP.
- Crops & targets
- All vegetation on non-crop land; residual 12+ months.
- Safety
- Leaches readily; do not apply over shallow water tables or near desirable plants' root zones.
- Field notes
- Often rotated or mixed with diuron and imazapyr to manage resistance and cost.
Imidacloprid
Insecticide
Neonicotinoid (IRAC Group 4A — nAChR agonist)
- Mode of action
- Systemic. Binds nicotinic acetylcholine receptors, causing paralysis and death; moves acropetally in the plant.
- Uses
- Sucking pests (aphids, whitefly, scale, psylla) in crops; lawn grub and mole-cricket control; termite barriers; tree injection for polyphagous shot hole borer programmes. 350 SC (Kohinor, Starbug class) in 5L is a recurring municipal and turf tender item.
- Crops & targets
- Aphids, leafhoppers, whiteflies, soil grubs, termites.
- Safety
- Highly toxic to bees — never spray flowering crops; observe pollinator label restrictions strictly.
- Field notes
- Soil drench gives 4–8 weeks protection; resistance common in whitefly — rotate with Group 4D/28.
Cypermethrin
Insecticide
Pyrethroid (IRAC Group 3A — sodium channel modulator)
- Mode of action
- Contact and stomach action; disrupts sodium-channel gating causing rapid knockdown.
- Uses
- Broad crop-pest control (bollworm, cutworm, leaf-eating caterpillars) and vector/structural pest control; 200 EC is a standard crop and municipal formulation.
- Crops & targets
- Chewing and sucking insects on most crops; flies and mosquitoes in public health.
- Safety
- Highly toxic to fish, bees and aquatic invertebrates — strict buffer zones around water.
- Field notes
- Synthetic pyrethroid resistance is widespread in some pests — use in rotation, not as sole chemistry.
Deltamethrin
Insecticide
Pyrethroid (IRAC Group 3A)
- Mode of action
- Potent pyrethroid with fast knockdown and long residual on surfaces.
- Uses
- Indoor residual spraying (IRS) for malaria vector control, stored-grain protection, crop pests. Decis/K-Othrine class; WP formulations specified in health-department tenders.
- Crops & targets
- Mosquitoes, flies, stored-product beetles, crop caterpillars.
- Safety
- Aquatic toxicity very high; cold-blooded animals (fish, reptiles) extremely sensitive.
- Field notes
- Among the most potent pyrethroids per gram — follow dilution tables exactly.
Lambda-cyhalothrin
Insecticide
Pyrethroid (IRAC Group 3A)
- Mode of action
- Fast-acting sodium-channel modulator; capsule-suspension (CS) forms extend residual.
- Uses
- Crop insects, turf pests, public-health residual sprays (Impact CS class).
- Crops & targets
- Caterpillars, aphids, beetles, cockroaches, ants.
- Safety
- Skin paresthesia common on exposure — wear coveralls and gloves.
- Field notes
- CS micro-encapsulation reduces odour and staining for structural use.
Fipronil
Insecticide
Phenylpyrazole (IRAC Group 2B — GABA antagonist)
- Mode of action
- Blocks GABA-gated chloride channels; contact and ingestion, with colony transfer in social insects.
- Uses
- Termite barriers and baiting, ant and cockroach gels, locust control, seed treatment. Regent/Terminator class.
- Crops & targets
- Termites, ants, cockroaches, locusts, soil insects.
- Safety
- Toxic to bees and aquatic life; restricted in some jurisdictions — confirm current registration.
- Field notes
- Gel baits (Domino class) exploit trophallaxis for colony elimination at very low doses.
Chlorpyrifos
Insecticide
Organophosphate (IRAC Group 1B — acetylcholinesterase inhibitor)
- Mode of action
- Irreversible AChE inhibition causing synaptic overstimulation.
- Uses
- Soil pests, termites (structural), certain crop pests. Registrations have narrowed sharply — many uses now restricted.
- Crops & targets
- Termites, cutworms, soil larvae where still registered.
- Safety
- Significant mammalian neurotoxicity; cholinesterase monitoring advised for regular handlers. Check current label before supply.
- Field notes
- 480 EC (Inhibitor 48 SC class) remains specified in older termite tenders; verify legal status per country.
Dimethoate
Insecticide
Organophosphate (IRAC Group 1B)
- Mode of action
- Systemic AChE inhibitor absorbed by roots and foliage.
- Uses
- Aphids, fruit fly, leaf miners in citrus, vegetables and field crops (400 EC).
- Crops & targets
- Sucking and mining insects.
- Safety
- Moderate-to-high acute toxicity; strict re-entry intervals.
- Field notes
- Being phased down in some markets — recommend alternatives (Group 4A, 28) where available.
Mercaptothion (Malathion)
Insecticide
Organophosphate (IRAC Group 1B)
- Mode of action
- Contact AChE inhibitor with relatively low mammalian toxicity.
- Uses
- Vector control (mosquito larviciding/adulticiding), grain protectant, garden insect control; 500 EC/ULV in health tenders.
- Crops & targets
- Mosquitoes, flies, stored-grain insects, garden pests.
- Safety
- Among the safer OPs but still an AChE inhibitor — standard OP precautions apply.
- Field notes
- ULV formulations for space spraying at very low volume.
Propiconazole
Fungicide
Triazole (FRAC Group 3 — DMI)
- Mode of action
- Systemic; inhibits C14-demethylation in ergosterol biosynthesis, disrupting fungal membranes.
- Uses
- Rusts, leaf spots and powdery mildew in cereals, turf and ornamentals (250 EC). Curative and protectant.
- Crops & targets
- Rust, powdery mildew, leaf spot, dollar spot in turf.
- Safety
- Growth-regulating side-effect on some ornamentals at high rates — follow label.
- Field notes
- Rotate with FRAC 11 (azoxystrobin) to delay resistance.
Azoxystrobin
Fungicide
Strobilurin (FRAC Group 11 — QoI)
- Mode of action
- Blocks mitochondrial respiration at the Qo site; broad-spectrum, translaminar.
- Uses
- Cereals, maize, vegetables, turf; excellent preventative activity (250 SC).
- Crops & targets
- Rusts, mildews, anthracnose, turf diseases.
- Safety
- Very phytotoxic to certain apple varieties — never use on or drift onto apples.
- Field notes
- High resistance risk when used solo — always mix or alternate with multi-site (mancozeb/chlorothalonil).
Chlorothalonil
Fungicide
Chloronitrile (FRAC Group M05 — multi-site)
- Mode of action
- Multi-site protectant disrupting multiple enzymes; negligible resistance risk.
- Uses
- Protectant backbone for vegetables, potatoes, turf (720 SC / 75 WP).
- Crops & targets
- Early/late blight, leaf spots, downy mildew (in mixes).
- Safety
- Protectant only — must precede infection; eye irritant.
- Field notes
- Ideal resistance-management partner for single-site fungicides.
Mancozeb
Fungicide
Dithiocarbamate (FRAC Group M03 — multi-site)
- Mode of action
- Multi-site protectant interfering with sulphydryl enzymes.
- Uses
- Potatoes, tomatoes, citrus, ornamentals (800 WP); cornerstone of blight programmes.
- Crops & targets
- Early blight, late blight, downy mildew (with cymoxanil), black spot.
- Safety
- Re-entry intervals apply; avoid in hot, wet conditions on sensitive crops.
- Field notes
- Cheap, effective, resistance-proof — the workhorse protectant.
Copper oxychloride
Fungicide / Bactericide
Inorganic copper (FRAC Group M01 — multi-site)
- Mode of action
- Copper ions denature enzymes on contact; protectant only.
- Uses
- Citrus, vines, tomatoes, potatoes; bacterial disease suppression (850 WP / 500 SC).
- Crops & targets
- Blight, leaf spot, bacterial canker, citrus scab.
- Safety
- Accumulates in soil with decades of use; phytotoxic in slow-drying conditions.
- Field notes
- Apply before rain/infection; compatible with most protectants.
Sulphur
Fungicide / Miticide
Inorganic (FRAC Group M02 — multi-site)
- Mode of action
- Vapour-phase multi-site action against powdery mildew and mites.
- Uses
- Powdery mildew in vines, cucurbits, roses; mite suppression (800 WP / dusts).
- Crops & targets
- Powdery mildew, eriophyid and spider mites.
- Safety
- Phytotoxic above ~30 °C and on sulphur-shy cucurbits; do not combine with oils within 14 days.
- Field notes
- Acceptable in organic production — a dual-use conventional/organic tool.
Metaldehyde
Molluscicide
Molluscicide
- Mode of action
- Neurotoxic to molluscs; causes excessive mucus production and dehydration.
- Uses
- Snail and slug control in gardens, crops and export orchards (pellets, 40 SC).
- Crops & targets
- Snails, slugs.
- Safety
- Attractive and toxic to dogs and wildlife — use pet-safer formulations and bait stations.
- Field notes
- Carbaryl-based baits are alternatives where metaldehyde is restricted.
Paraquat
Herbicide
Bipyridylium (HRAC Group 22 — photosystem I diverters)
- Mode of action
- Contact; generates reactive oxygen species destroying green tissue within hours.
- Uses
- Fast burndown pre-plant, inter-row and directed sprays (200 SL). Restricted/prohibited in some countries — confirm legality before supply.
- Crops & targets
- All green tissue contacted; no soil activity.
- Safety
- Extremely toxic if swallowed — no antidote. Handle with full PPE; keep secure.
- Field notes
- Still appears in some regional tenders; glufosinate or glyphosate are alternatives where paraquat is banned.
Diquat
Herbicide
Bipyridylium (HRAC Group 22)
- Mode of action
- Contact desiccant, similar to paraquat but registered for aquatic and potato-haulm uses in some markets.
- Uses
- Aquatic weed control, haulm desiccation, pre-harvest drying (200 SL).
- Crops & targets
- Aquatic weeds, potato haulms, annual weeds.
- Safety
- Corrosive to eyes and skin; strict PPE.
- Field notes
- Check aquatic-use registration per country.
Metsulfuron-methyl
Herbicide
Sulfonylurea (HRAC Group 2 — ALS inhibitor)
- Mode of action
- ALS inhibition at very low use rates; systemic with soil residual.
- Uses
- Broadleaf control in cereals, turf and non-crop areas (600 WG); brush mixes.
- Crops & targets
- Broadleaf weeds incl. khaki burr, cosmos.
- Safety
- Very low rates — measure precisely; sprayer contamination damages broadleaf crops.
- Field notes
- Tank-clean with Flushall after use.
Clethodim
Herbicide
Cyclohexanedione (HRAC Group 1 — ACCase inhibitor)
- Mode of action
- Selective ACCase inhibitor killing grasses in broadleaf crops.
- Uses
- Grass weeds in soya, sunflower, vegetables and orchards (120 EC).
- Crops & targets
- Annual and perennial grasses.
- Safety
- Low broadleaf phytotoxicity; add crop oil for full efficacy.
- Field notes
- Rotate with glyphosate/glufosinate to manage ryegrass resistance.
Pendimethalin
Herbicide
Dinitroaniline (HRAC Group 3 — microtubule inhibitor)
- Mode of action
- Pre-emergence root/shoot growth inhibition in germinating weeds.
- Uses
- Pre-emergence control in maize, onions, vegetables, turf (330/455 EC).
- Crops & targets
- Annual grasses and small-seeded broadleaf weeds.
- Safety
- Orange staining of surfaces; incorporate lightly for activation.
- Field notes
- Needs soil moisture to activate.
Acetochlor
Herbicide
Chloroacetamide (HRAC Group 15 — VLCFA inhibitor)
- Mode of action
- Shoot-absorbed pre-emergence inhibitor of very-long-chain fatty acid synthesis.
- Uses
- Pre-emergence grass and sedge control in maize (900 EC).
- Crops & targets
- Annual grasses, yellow nutsedge.
- Safety
- Apply pre-emergence; limited post-emergence activity.
- Field notes
- Often pre-mixed with atrazine for broad-spectrum maize programmes.
S-metolachlor
Herbicide
Chloroacetamide (HRAC Group 15)
- Mode of action
- Pre-emergence VLCFA inhibitor with improved selectivity over metolachlor.
- Uses
- Maize, soya, sunflower pre-emergence grass control (960 EC).
- Crops & targets
- Annual grasses and some sedges.
- Safety
- Needs incorporation or rainfall within days of application.
- Field notes
- Dual Gold class; standard in conservation-tillage programmes.
Diuron
Herbicide
Substituted urea (HRAC Group 5)
- Mode of action
- Residual PSII inhibitor, root-absorbed.
- Uses
- Industrial bareground, orchards, sugarcane (800 SC/WP).
- Crops & targets
- Germinating weeds; residual months.
- Safety
- Watercourse contamination risk — buffer zones mandatory.
- Field notes
- Mixes with bromacil/hexazinone for extended residual.
Hexazinone
Herbicide
Triazinone (HRAC Group 5)
- Mode of action
- Root- and foliar-absorbed PSII inhibitor active on woody plants.
- Uses
- Industrial weed control, forestry site preparation, bush control (250 SL).
- Crops & targets
- Woody weeds, grasses on non-crop land.
- Safety
- Mobile in soil — groundwater caution.
- Field notes
- Velpar class; effective by spot-gun soil application.
Brodifacoum
Rodenticide
Second-generation anticoagulant (AVK)
- Mode of action
- Vitamin-K antagonist causing fatal internal haemorrhage after a single feed.
- Uses
- Rat and mouse control in bait stations around food premises, warehouses, farms (blocks, pellets, wax).
- Crops & targets
- Rattus norvegicus, R. rattus, Mus musculus.
- Safety
- Severe secondary-poisoning risk to owls and pets — always use secured bait stations and recover carcasses.
- Field notes
- Rotate with coumatetralyl to manage anticoagulant resistance.
Coumatetralyl
Rodenticide
First-generation anticoagulant
- Mode of action
- Anticoagulant requiring multiple feeds; lower secondary-poisoning profile.
- Uses
- Rodent control where non-target risk is high (Racumin class).
- Crops & targets
- Rats and mice.
- Safety
- Still hazardous to pets — bait stations required.
- Field notes
- Preferred near raptor conservation areas.
Zinc phosphide
Rodenticide
Acute rodenticide
- Mode of action
- Releases phosphine gas in the stomach — acute, single-feed kill.
- Uses
- Field rodent outbreaks (gerbils, multimammate rats) and mole control.
- Crops & targets
- Field rodents.
- Safety
- No antidote; extremely dangerous to all mammals — trained applicators only.
- Field notes
- Use pulses between anticoagulant programmes.
Aluminium phosphide
Fumigant
Fumigant (phosphine generator)
- Mode of action
- Releases phosphine (PH₃) on contact with moisture; disrupts cellular respiration.
- Uses
- Stored-grain, silo and commodity fumigation (tablets/pellets, Phostoxin class). Restricted — certified fumigators only.
- Crops & targets
- All stored-product insects and rodents in sealed structures.
- Safety
- Lethal gas; requires Fumiscope monitoring, SCBA standby and clearance certification.
- Field notes
- Tendered by grain boards and ports; sale restricted to licensed operators.
Mineral oil (spray oils)
Adjuvant / Insecticide
Adjuvant / physical insecticide
- Mode of action
- Physical — smothers scale, mite eggs and soft-bodied insects; as adjuvant, improves spreading and cuticle penetration.
- Uses
- Dormant and summer oil sprays for citrus and deciduous fruit; standard oil carrier for cut-stump arboricide mixes (Actipron Super, H&R Crop Oil 822 EC).
- Crops & targets
- Scale, mealybug, red spider mite eggs.
- Safety
- Phytotoxic above 30 °C or with sulphur within 14 days.
- Field notes
- George Municipality tender item 6 specifies mineral oil 822 g/l in 20L — covered by H&R Crop Oil and Performer 363 EW.
Ammonium sulphate (AMS adjuvants)
Adjuvant
Water conditioner
- Mode of action
- Sequesters hard-water cations (Ca²⁺, Mg²⁺) that antagonise glyphosate and other weak-acid herbicides; lowers spray pH.
- Uses
- Add to every glyphosate tank on borehole water (Amsul-50, Hyperboost, Booster AS, Balancer).
- Crops & targets
- Improves efficacy of glyphosate, 2,4-D, glufosinate.
- Safety
- Low hazard; corrosive to mild-steel equipment over time.
- Field notes
- Typically 1–2% v/v; add first, before herbicide.