School Science Lessons
(Foodgardens7a)
2024-09-17
Insecticides
Contents
4.5a Organochlorine insecticides
4.5b Organophosphate and carbamate insecticides
4.5c Fungicides
4.5a Organochlorine insecticides
4.3.0 Organochlorine insecticides, organochlorides, chlorinated hydrocarbons
4.4.01 Cyclodiene pesticides, aldrin, chlordane, dieldrin, endosulfan, endrin, heptachlor
4.3.1 DDT
4.3.3 Lindane, gammexane, BHC, benzene hexachloride
4.3.2 Methoxychlor
4.3.2.1 Piperonyl butoxide
4.5b Organophosphate and carbamate insecticides
4.4.1 Acephate
4.4.7.0 Carbaryl
4.4.7.1 Bendicarb
4.4.8 Methiocarb
4.4.2 Dimethoate
4.4.3 Malathion, Maldison
4.4.4 Naled
4.4.5 Tetrachlorvinphos
4.4.6 Trichlorophon
4.5c Fungicides
4.6.2 Bordeaux mixture, CuSO4.3Cu(OH)2.3CaSO4
4.6.3 Captan, C9H8Cl3NO2S
4.6.4 Copper oxychloride, ClCu2H3O3
4.6.5 Chlorothalonil
4.6.7 Metam-sodium
4.6.8 Quintozene
4.6.6 Zineb
4.3.0 Organochlorine compounds, organochlorides (chlorinated hydrocarbons)
Safety: Do not use organochlorine compounds in school gardens.
1. The following organochlorine compounds have been banned in Australia and must not be used in schools:
Aldrin, BHC, Chlordane, DDT, Dieldrin, Endrin, Heptachlor, Hexachlorophene, Isodrin, Lindane, Pentachlorophenol (PCP) C6HCl5O, 2,4,5-T.
2. The following pesticides are too dangerous for use in school food gardens:
2.1 Organochlorine compounds: DDT, benzene hexachloride (Lindane, gammexane BHC), aldrin (chlordane, dieldrin, heptachlor epoxide, endrin).
Organochlorines are composed only of carbon, hydrogen and chlorine.
They are biologically very active, but not easy to breakdown, hence persistent.
They have one or more chlorine atoms attached to the carbon atoms, replacing hydrogen.
The term "organochlorine" refers to a wide range of organic chemicals, which contain chlorine and sometimes several other elements.
They have been used in Australia as herbicides, insecticides, fungicides and industrial chemicals, e.g. polychlorinated biphenyls (PCBs).
They are very stable compounds that can be distributed in the environment, where they persist long after their original use.
They degrade slowly and being fat soluble, accumulate in the food chain, eventually ending up in the fat of the human body.
The key properties of organochlorines that cause concerns are persistence and toxicity.
Organochlorine pesticides were manufactured for their toxicity.
They were also persistent sp had advantages in that they remained effective against target pests for prolonged periods.
They are used to protect crops, livestock, buildings and households from the damaging effects of insects.
Commonly used organochlorine compound insecticides were DDT, Lindane, chlordane, dieldrin, aldrin and heptachlor.
Fungicides included hexachlorobenzene (HCB) and chlorinated phenols, e.g. pentachlorophenol.
Herbicide 2,4,5-T was also used.
Hexachlorobenzene (HCB) was used in the past as a fungicide (seed disinfectant, seed paint), but is now banned in Australia.
It was deregistered for general use between 1985 and 1987.
Chlorinated phenols, e.g. pentachlorophenol (PCP) have been widely used in Australia to protect softwood timber from decay.
Also, 2,4 5-T was used in the past as a herbicide against broad leaf woody plants, as a defoliant.
The use of almost all the chemicals mentioned above is now banned in Australia.
4.3.1 DDT
Safety: Do not use DDT in school gardens.
DDT, the new chemical name is 1,1-bis(4-chlorophenyl)-2,2,2-trichloroethane.
The old name was dichlorodiphenyltrichloroethane, hence "DDT".
DDT is a organochlorine contact insecticide that kills by acting as a nerve poison.
It is a highly effective insecticide, and is of very low toxicity to mammals.
It is odourless and tasteless, has a high persistence, and is chemically stable.
However, insects can develop resistance to DDT by natural selection of surviving members with enzymes that can detoxify it.
DDT and its metabolic breakdown product can accumulate in the fat of birds and fish, and even people, at the end of the food chain.
It may cause birds to produce thin shell eggs that break easily.
So the advantage of it being chemically stable is now seen as a major disadvantage.
It was also used in large quantities in the control of mosquitoes, which caused malaria in tropical countries.
There has been a total ban on the use of DDT in Australia since 1987.
The technical product "DDT", which is a mixture of isomers, principally p,p'-DDT, with lesser amounts of o,p'-DDT.
Once stored in fatty tissue, DDT residues are sequestrated and stabilized, unless they are mobilized either by lactation or great weight loss.
They are all strongly suspected of being environmental endocrine disruptors, i.e. chemicals that affect the hormonal system.
4.3.2 Methoxychlor
Safety: Do not use Methoxychlor in school gardens.
See diagram Methoxychlor
Methoxychlor, C16H15Cl3O2, is an organochlorine insecticide.
It is a contact and stomach poison, very safe to use, and has long persistence.
Methoxychlor is pale yellow powder and has a fruity or musty odour.
It is used to kill flies, mosquitoes, cockroaches, chiggers and others.
Methoxychlor is a general insecticide for food crops, household pests, farm animals, pets and grain storage.
It is available as wettable powder (W.P.), emulsifiable concentrate (E.C.), dusts, and in aerosol cans.
It has oestrogenic effects on mammals.
Methoxychlor is a biodegradable analogue of DDT.
While non-polar compounds, e.g. DDT, stay dissolved in the fat of the body, polar substances, e.g. methoxychlor, are water soluble and can be excreted to
be further attacked by other organisms.
DDT and pyrethrins keep open the sodium channel of the insect nerve cell, but not the mammal nerve cell, so sodium ions leak in causing continuous
transmission of nerve impulses.
The insect dies of exhaustion and you can observe the frantic activity of house flies sprayed with DDT.
When DDT sprays were introduced an advertisement stated "They fly outside to die".
Methoxychlor can enter your body when you breathe contaminated air, eat contaminated food, get it on your skin and use garden products or pet sprays.
High doses of methoxychlor could cause damage to the nervous system, but low levels of methoxychlor will leave the body so quickly that this type of damage is not likely.
The US Environmental Protection Agency (EPA) has set a reference dose (RfD) for methoxychlor at 0.005 milligrams per day.
4.3.2.1 Piperonyl butoxide, PBO, C19H30O5
Synthetic pyrethroids contain natural pyrethrum with the synergist piperonyl butoxide, but these products are not allowed in some countries.
DDT, methoxychlor, and pyrethrins are more efficient if piperonyl butoxide (PBO) is already added to the insecticide to give a synergistic effect.
This additive is not itself an insecticide, but it deactivates enzymes for detoxification of the pesticide in the insect.
4.3.3 Lindane
Do not use Lindane in school gardens.
Lindane, C6H6Cl6 or ClCH(CHCl)4CHCl, beta-HCH, 1,2,3,4,5,6-Hexachlorocyclohexane, gamma-HCH, gamma-hexachlorocyclohexane (γ-HCH), gammaxene, [wrongly-named, benzene hexachloride (BHC)], variant of hexachlorocyclohexane, (HCB).
Benzene hexachloride, chlorothalanil, DCPA, dalapon.
Lindane, is an insecticide with different names, made by the addition of chlorine to benzene.
The 7-isomer is the insecticide of the nine isomers formed.
The insecticide Lindane is more than 5-20 times more toxic to insects than DDT.
Lindane, gamma-isomer of benzene hexachloride, is a a colourless crystalline solid with a slight musty odor that emits toxic fumes of hydrochloric acid and other chlorinated compounds when heated to decomposition.
Lindane is used as an insecticide for hardwood logs and a topical pediculicide and scabicide
Inhalation exposure to Lindane causes severe irritation of the nose and throat, and affects the liver, and other body systems.
Lindane has not been produced in the United States since 1976, but is imported for insecticide use.
It was used for control of insect pests in stored seed, to control white grubs in pineapples, against ectoparasites on food.
It was deregistered for general use in 1985.
Generic Lindane is still available by prescription for head lice, but it appears that Lindane is not as effective against lice as it once was.
Hexachlorobenzene has been used as a pesticide, but is no longer registered for this use in Australia.
4.4.0 Organophosphate and carbamate insecticides
Do not use organophosphate and carbamate insecticides in school gardens.
Organophosphorus insecticides
The following pesticides are too dangerous for use in school food gardens:
Organophosphorus insecticides: chlorpyrifos, parathion, malathion, dimethoate, dichlorvos, mevinphos.
High persistence chlorinated pesticides are being replaced by the organophosphorus group that has a range of activity, persistence, and specificity.
Their general formula is (RR'X) P = 0, where R and R' are short chain groups and X is a group that it is easily removed from the molecule either after a
reaction in the body, so persistence is reduced, e.g. carbaryl.
4.4.01 "Cyclodiene" pesticides, aldrin, chlordane, dieldrin, endrin, heptachlor
Do not use "Cyclodiene" pesticides in school gardens.
Chlordane, aldrin, dieldrin, heptachlor, endosulfan
Hexachloropentadiene, C5Cl6 (Diels-Alder reaction) --> cyclodienes, e.g. aldrin C12H8Cl6, chlordane C10H6Cl8, dieldrin C12H8Cl6O, endrin C12H8Cl6O, endosulfan, C9H6Cl6O3S, heptachlor C10H6Cl7.
These pesticides are now banned in most countries.
They are broad spectrum insecticides, highly toxic to insects and mammals, and with high persistence.
They also accumulate in body fats and act on the central nervous system.
The compound may itself be non-toxic, but is converted to a toxic form in the body.
They remain in the mammal body, measured as a half residence time, to be detoxified in the liver and excreted by the kidneys, leaving some stored in body
fat to be released during illness, stress and lactation, maternal milk.
Aldrin and dieldrin are active against insects by contact or ingestion.
Their primary use was for the control of termites around buildings, corn pests by application to soil and in the citrus industry, termite proofing of plastic and
rubber coverings of electrical and telecommunication.
In 1970, the US Department of Agriculture cancelled all uses of aldrin and dieldrin based on the concern that these chemicals could cause severe aquatic environmental change and are potentially carcinogenic, so Aldrin and dieldrin have not been produced in the United States since 1974.
Aldrin and dieldrin are classified as hazardous wastes that should be incinerated.
Aldrin was used as a soil treatment, pre-planting, for crops, e.g. sugar cane, it was used in ant control as well as subterranean termite control, the protection
of power poles from termites, and domestic control of fleas, flies, lice and mites.
Chlordane, dieldrin, aldrin and heptachlor, were marketed to complement DDT.
Chlordane was used to control termites, various types of ants, borers, lawn beetles, curl grubs, cut worms and black beetles.
Dieldrin was used against locusts and argentine ants, in the protection of electricity and telephone cable, soil treatment in farm and industrial premises for
control of termites in buildings, fences and similar structures.
Endosulfan was used widely to control insect pests, but is now banned or is being banned in most countries, because of its acute neurotoxic properties.
Heptachlor, a persistent organic pollutant, was used similarly to chlordane, in soil treatment in crops for control of funnel ants and grubs of the grey-black
beetle in cane growing areas, and banana beetle borer in banana plantations.
In some countries it still has a limited use to control fire ants.
4.4.1 Acephate, C4H10NO3PS, Orphene
Do not use acephate in school gardens.
Acephate is a contact poison that is also systemic in some plants.
It is fairly safe to use, but there should be a 7 days witHolding period before harvest of the sprayed crop.
It persists for some time and it may burn young leaves.
Acephate can be used to control many insect pests and some people say it is the best general purpose insecticide for use in the tropics.
It can control aphids and thrips, caterpillars, leaf miners, rice hoppers, diamond-backed moths, cutworms, and many other insects.
Acephate is usually available as a wettable powder and as a dust.
4.4.2 Dimethoate, C5H12NO3PS2.
Do not use dimethoate in school gardens.
Dimethoate, "Pestanal", organophosphate insecticide, systemic poison, dangerous if mist is breathed in or swallowed.
There should be a 7 days witHolding period before harvest of the sprayed crop and it may damage some fruit trees.
Dimethoate can be used to control all sucking insects, but it will not control chewing insects, e.g. grasshoppers.
Dimethoate can control leaf miner, aphids and thrips, corn ear worm, red spider, bean fly, and fruit fly.
When insects are first seen, spray a solution of 5 mL of dimethoate concentrate in 5 litres of water, and make sure that the whole plant is sprayed.
Dimethoate is available as emulsifiable concentrate (E.C.), dusts, wettable powder (W.P.) and granules.
4.4.3 Malathion, Maldison, C10H19O6PS2
Do not use malathion in school gardens.
Malathion is a wide spectrum aliphatic organophosphate.
Malathion is a synthetic phosphorous compound and cholinesterase inhibitor allowing acetylcholine to accumulate at cholinergic synapses and enhancing
cholinergic receptor stimulation, leading to insect death.
Malathion is a widely-used agricultural chemical to control corn earworm, sucking insects, including mosquitoes and head lice.
Contact with skin, inhalation of spray or swallowing may be harmful.
Malathion, maldison, is a contact poison that is also weakly systemic in some plants.
It is fairly safe to use, but the concentrate is dangerous if swallowed, breathed in, or allowed to remain on the skin.
There should be a 7 days' witHolding period before harvest of the sprayed crop.
It persists for some time.
Malathion can be used to control many different insect pests that eat leaves and stems, but some insects have become resistant to it.
It is used to control aphids, mole crickets, grasshoppers, cutworms, scale insects on citrus trees, bugs on pumpkin, spider mites.
When the insects are first seen spray a solution of 10 mL of "Malathion 50" in 4 litres of water, and repeat the spray when necessary.
Malathion is usually available as a concentrate.
It is also available as aerosols, granules and dusts.
For control of scale insects mix with white oil, e.g. Albarol, and water.
For control of pests of stored products, use as a dust.
4.4.4 Naled, C4H7Br2Cl2O4P.
Do not use naled in school gardens.
Naled, bromochlorphos, is a contact and stomach poison.
It is dangerous to use.
Naled can be used just before harvest.
It can control caterpillars, cutworms, bugs on eggplants, red spider mite on cassava and other crops.
Naled is available as an emulsifiable concentrate (E.C.), and a dust.
4.4.5 Tetrachlorvinphos, C10H9Cl4O6P.
Do not use tetrachlorvinphos in school gardens.
Tetrachlorvinphos, "Rabon", "Gardona" is a contact and stomach poison.
This chemical is not allowed to be used on crops in the US.
Tetrachlorvinphos can be used to control caterpillars and other pests of leafy vegetables, but other insecticides are better for this purpose.
It can be used to kill parasites of animals and to kill pests in agricultural buildings and is used in dog collars to control fleas.
Tetrachlorvinphos is usually available as emulsifiable concentrate (E.C.) oil solution and dusts.
4.4.6 Trichlorophon, C4H8Cl3O4P.
Do not use trichlorophon in school gardens.
Trichlorphon, "Dipterex", "Chlorophos", is a stomach poison and contact insecticide for certain insects.
It also is used to kill flies and cockroaches.
It is dangerous to use.
There should be a 2 days witHolding period before harvest of the sprayed crop.
Trichlorphon is used to control cutworm of cabbage, white fly on taro, corn ear worm, bean fly, bugs, leaf hoppers, banana scale moth and fruit fly.
It is not effective for control of diamond backed moth.
Trichlorphon is available as wettable powder (W.P.) emulsifiable concentrate (E.C.) and dusts.
4.4.7.0 Carbamates, Carbaryl, C12H11NO2.
Do not use carbamates, carbaryl in school gardens.
Carbaryl, 1-napthyl methylcarbamate, "Sevin", "Carbamine", "Dicamba", "Bugmaster".
Carbaryl is a contact poison that is also weakly systemic in some plants.
It is fairly safe to use, but the concentrate is dangerous if it is swallowed, breathed in or allowed to remain on the skin.
There should be a 7 days witHolding period before harvest of the sprayed crop.
It has a short persistence.
It may burn young leaves.
Carbaryl is used to control insect pests that eat leaves and stems, but a following spray is needed to kill all the insect pests.
It can control leaf miner on hibiscus cabbage (aibika), okra, tomato and sweet potato, caterpillar on cabbage and other leafy vegetables, 28-spotted
ladybird on the pumpkin family, tomato leaf miner, pod borers in bean, bugs on bean and eggplant, green looper caterpillars on bean and tomato,
diamond-backed moth on cabbages, taro leaf hopper, white fly on taro and other crops, army worm, pumpkin beetle, moths on fruit trees, potato moths.
When the insects are first seen, spray a solution of 5 g of Carbaryl in 4 litres of water, and repeat the spray when necessary.
Carbaryl is usually available as a wettable powder.
It is also available as granules and dusts.
For control of scale insects mix it with white oil (petroleum oil).
4.4.7.1 Carbamates, Bendicarb, C11H13NO4
Do not use carbamates in school gardens.
Bendicarb, insecticide, Acutely toxic
Registration was cancelled in USA 1999, "Ficam", "Multimat".
4.4.8 Carbamates, Methiocarb, C11H15NO2S
Do not use carbamates in school gardens.
Methiocarb, mercaptodimethur, 4 methyl thio-3,5-xylyl methylcarbamate
Methiocarb, a white crystalline powder with a mild odour, is a contact and stomach poison insecticide, acaracide, molluscicide and bird repellent.
It is dangerous with long residual activity, but has no systemic action.
Methiocarb is used mainly as snail bait and repellent for snails and slugs.
It also controls grasshoppers, mites and many insects.
4.6.2 Bordeaux mixture, CuSO4.3Cu(OH)2.3CaSO4
Bordeaux mixture: Do not use in school gardens.
Safety: Gloves, face protection and protective clothing must be worn by anyone with a sensitive skin or allergy, during mixing and spraying operations.
Keep ingredients and the mixtures secure, labelled and out of reach of children.
Do not use in school gardens.
"Bordo Mixture", is a mixture of copper (II) sulfate and calcium hydroxide, (slaked lime, hydrated lime).
It is a protective fungicide that is safe, unless eaten.
The two chemicals are often bought separately and mixed in a plastic bucket and used immediately.
It may burn leaves and metal and is hard to use properly.
Bordeaux mixture can a wide range of fungus diseases, including rots, downy mildew and leaf spots.
It repels many insects and it can kill the eggs of mites.
Copper (II) sulfate may be used by itself to control leaf spots and other diseases.
Use Bordeaux mixture to kill moss.
4.6.3 Captan, C9H8Cl3NO2S
Do not use captan in school gardens.
Safety: Suspected of causing cancer, Toxic if inhaled, Keep out of reach of children.
Captan is ethanethiol or ethyl mercaptan, C9H8Cl3NO2S.
It is a protective fungicide and is safe to use, but may irritate the skin, and it kills fish.
It is used mainly as a dust on seeds to prevent damping off disease, also used on vegetables and other crops and as a dip for stored products.
It has a one day witHolding period.
It is a good all purpose fungicide for controlling mildew and leaf spots and damping off fungus on seeds.
Captan can control root and stem rot of bean, fungus diseases in carrots, peanut and sorghum, and leaf spot of yams.
Seed that has been dusted with Captan must not be eaten.
Captan is available as dusts and WP, and in special soil fungicidal products.
In 1989, Captan was phased out of general usage as a pesticide in USA.
4.6.4 Copper oxychloride, ClCu2H3O3
Do not use copper oxychloride in school gardens.
Copper oxychloride safety: No adverse health effects are expected when the product is used in accordance with label directions.
Copper oxychloride is made from copper and chlorine.
It is a protective fungicide.
There should be a one day witHolding period before harvest.
Copper oxychloride is a good fungicide for leaf diseases.
It can control a wide range of fungus diseases, including anthracnose, leaf rots, leaf spots, downy mildew, and powdery mildew.
Copper oxychloride is available as wettable powder (W.P.) and dusts.
3.28 Stems and roots (Primary)
Soft rots occur in the hearts of leafy vegetables and can be controlled by watering only in the mornings, not planting closely, using copper oxychloride.
Leaf tip burn in leafy vegetables can be caused by soil with very low pH, which can be controlled by adding lime to the soil.
Other leaf burns can be caused by using pesticides or weedicides that are too concentrated.
4.6.5 Chlorothalonil, C8Cl4N2.
Do not use in chlorothalonil in school gardens.
It is a protective fungicide and its effect lasts a long time.
It is safe, but it makes some people sick, and it can kill fish.
It is the best fungicide for fungus diseases of tomato.
Chlorothalonil can control leaf spots, powdery mildew, downy mildew and other fungi on plants.
It does not kill all soil fungi.
Chlorothalonil is available as wettable powder (W.P.) and tablets.
4.6.7 Metam-sodium, C2H4NNaS2
Do not use metam-sodium in school gardens.
Metam-sodium fungicide is often just called "metam"
It is a carbamate salt containing sodium, which is used to kill fungi, insects, nematodes and weeds in the soil.
It is a yellow to light yellow-green solution with an odour of amine and sulfur that varies in intensity.
It is fairly safe to use, but may irritate the eyes and mouth.
4.6.8 Quintozene, C6Cl5NO2
Do not use quintozene in school gardens.
It is a protective fungicide for seed and soil.
It is fairly safe to use, but may cause skin irritation and it may burn young leaves.
It can be used as a soil drench after planting to control various fungus diseases, e.g. damping off fungus and rots.
I t is applied to soil before sowing or after sowing to treat both seeds and soil.
It can be used to treat soil at transplanting and treat seeds of cabbages.
Seeds that have been treated with it must not be eaten.
It does not kill many kinds of fungi and it cannot be used to control bacterial wilt.
It is available as dusts, granules, and pastes.
4.6.6 Zineb C4H6N2S4Zn
Zinc ethylenebisthiocarbamate
Do not use zineb in school gardens.
It is a protective fungicide.
It is fairly safe to use, but it may cause skin irritation.
It may damage young seedlings.
There should be a 7 days witHolding period before harvest of the sprayed crop.
This is the best general purpose fungicide.
Zineb can control many vegetable fungus diseases including downy mildew on plants of the pumpkin family, leaf spots and rust diseases.
It is available as a wettable powder (W.P.) and as dusts.