School Science Lessons
2024-05-30
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Agricultural chemicals
Table of Contents
Preface
4.0 Agricultural chemicals
4.1 Acaricides
4.2 Arboricides
4.3 Fungicides
4.4 Herbicides, weedicides
4.5 Insecticides
4.6 Pesticides
4.8.3 Rodenticides
4.7 Sprays, dusts, white oils
4.8 Plant pests
4.9 Plant diseases
4.1 Acaricides
Do not use acaricides in school gardens.
Acaracides are used to kill red spider, mites and other 8-legged pests.
1. Dicofol, C14H9Cl5O, is a contact poison of mites only with long residual action, does not harm insects, is fairly safe, is not systemic, but may burn eggplant (aubergine), and other fruit.
The withholding period is 7 days.
Dicofol can control mites on citrus trees and red spider mite on passion fruit, banana, cassava and other crops, but Dimethoate is better.
Highly inflammable, do not smoke near it.
Dicofol is available as emulsifiable concentrate (E.C.), as wettable powder (W.P.), and as dusts.
See diagram 16.13.5: Dicofol.
2. Formaldehyde (formalin) can be used as a soil drench that prevents damping off disease of seedlings, but it will irritate eyes and nose.
3. Naled: 4.4.4
4. Dimethoate: 4.4.2
5. Sulfur, Wettable sulfur: 4.3.3
4. Methiocarb:4.4.8
4.2 Arboricides
No arboricides should be used in school gardens.
Arboricides are chemicals used to kill trees.
The most widely used arboricide is sodium arsenite, Na3As, which is highly poisonous to humans and other mammals.
Arboricides should be used correctly and stored and disposed of safely.
4.3 Fungicides
Fungicides are chemicals that kills fungus.
Fungicides may be harmful to humans and farm animals and should be used correctly and stored and disposed of safely.
Farm workers should wear protective clothing and trained in the use of all agricultural chemicals.
4.6.2 Bordeaux mixture
4.6.3 Captan
4.6.4 Copper oxychloride
4.6.5 Chlorothalonil
4.3.1 Lime sulfur, CaSx
4.6.7 Metam-sodium
4.3.2 Potassium permanganate, Condy's Crystals
4.6.8 Quintozene
4.3.3 Sulfur, wettable sulfur
4.3.4 "Yates Anti Rot Phosacid"
4.6.6 Zineb
4.4 Herbicides, weedicides
4.4.0 Herbicides
4.4.1 (2,4-D), (2,4-dichlorophenoxyacetic acid)
4.4.2 (2,4,5-T), (2,4,5-trichlorophenoxyacetic acid)
4.4.3 Acetochlor
4.4.4 Bifenox
4.4.5 Dalapon
4.4.6 Dinoseb
4.4.7 DCMU
4.4.8 Ethephon phosphonate
4.4.9 Glyphosate
4.4.10 MCPA
4.4.11 Paraquat
4.4.12 Weeds of National Significance (WONS), Australia
4.5 Insecticides
9.2.0 Bti insecticide, as powder or spray, controls some caterpillars
4.5.0 Insecticides
4.5.1 Inorganic chemical insecticides
4.8 Insect pests of plants
4.5.2 Insecticide types, contact, ingestion, systemic
4.5a Organochlorine insecticides
4.5b Organophosphate and carbamate insecticides
4.5.3 Pyrethrin, Plant extract insecticide
4.5.4 Rotenone, Plant extract insecticide
4.5.5Neonicotinoid insecticides
4.6 Pesticides
4.6.0 Pesticides definitions
4.6.1 Pesticides and herbicides safety
4.6.2 Pesticide safety
4.6.3 Pesticide safety, FIRST AID
4.18.0 Pesticide safety
Websites, Plant protection, pests and diseases
4.6.4 Active constituent
4.6.5 Chemical pesticides, poisons
4.6.6 Control of pests and diseases
4.24 Crop care
4.6.8 Emulsifying agents
4.6.9 Fumigants
4.6.10 Granules
4.6.11 Insect repellents
4.6.12 Integrated pest management (IPM)
4.3.1 Lime sulfur, CaSx
4.6.14 Mancozeb
4.6.15 Maneb
4.6.16 Persistence
Pherome traps, species specific, female sex hormone
4.6.17 Resistance to pesticides
4.6.18 Surface-acting agents
4.6.19 Synergists
4.6.20 | W / V | W / W |
4.6.21 Withholding period
4.7 Sprays, dusts, white oils
4.7.5 Sprayers and dusters
4.7.0 Sprays, dusts, white oils
4.7.6 Oil sprays
4.7.1 Chilli spray
4.7.4 Diatomaceous earth absorbacide
4.7.2 Garlic spray
4.7.3 Nicotine spray
4.8 Plant pests
See diagram 9.303: Plant pests.
4.8.0 Insect pests collection
4.8.1 The main pests of crops
4.9 Plant diseases
See diagram 6.0.1: Sterilizing soil.
The three main causes of diseases in plants:
4.9.1 1. Fungi diseases of plants
4.9.2 2. Bacteria diseases of plants
9.4 3. Virus diseases of plants
4.9.7 Nodules and galls
4.3.1 Lime sulfur, CaSx
Lime sulfur, CaSx, can be used only by the teacher in school gardens.
Lime sulfur, calcium polysulfide, lime sulfur, CaSx, orange-red, pH 10-12, [Ca(OH)2 + S], is an agricultural fungicide.
It contains calcium and sulfur.
It is a fungicide, acaricide and insecticide that is sprayed or dusted on plants.
This is a hard spray to use properly, it can be dangerous to use and it causes skin irritation.
It may burn leaves and metal.
It can control many fungus diseases, e.g. leaf spots and powdery mildew and it can control red spider and mite and scale insects.
It may damage plants in the pumpkin family.
Lime sulfur is available as a solution or a powder.
Use lime sulfur, CaSx to kill moss.
4.3.2 Potassium permanganate, Condy's crystals
Potassium permanganate, Condy's crystals, can be used only by the teacher in school gardens.
Potassium permanganate, KMnO4
Potassium permanganate solution controls powdery mildew.
4.3.3 Sulfur, wettable sulfur
Sulfur, wettable sulfur can be used only by the teacher in school gardens.
Avoid contact with eyes, skin and avoid breathing the vapour or dust.
Wear appropriate protective clothing.
It is a non-metallic element and is used as "Wettable sulfur".
It is a fungicide and acaricide.
It is safe to use, but it irritates the eyes and skin.
It may damage leaves of plants in the pumpkin family.
There is no withholding period.
It can control mites on capsicums, citrus hibiscus cabbage and tomato.
It can control powdery mildew, downy mildew and some rust diseases, but it is not effective for other fungus diseases.
Sulfur is available as a dust, wettable powder and sulfur paste.
Some people mix wettable sulfur with canola oil to make a spray.
4.3.4 "Yates Anti Rot Phosacid"
Do not use Phosacid in school gardens.
The phosphorous acid in "Yates Anti Rot" Phosacid inhibits the growth of fungus and enhances the defence system of plants.
It breaks down in soil and does not harm the environment.
It controls collar rot in citrus and ornamentals, root rot in citrus, avocados and ornamentals (including native plants, luculias, daphne and proteas) and downy mildew in grapes.
It is sprayed over the foliage where it is absorbed into the plant.
It has no withholding period, so it can be sprayed up to harvest.
4.4.0 Herbicides
Herbicides, weedicides, commonly called weedkillers, are chemicals that are poisonous to plants and are used to kill unwanted plants.
Some herbicides cause a range of health effects ranging from skin rashes to death.
Herbicides should be used correctly and stored and disposed of safely.
Dishwashing liquids contain surfactants (surface-acting agents) that may be added to herbicides to reduce the surface tension on the leaves of sprayed plants to allow the herbicide to stick evenly to the leaf surface and ensure maximum absorption.
This process is valuable when spraying leaves with a wax or hair surface, because it stops formation of beads of weedicide apart from the leaf surface.
However, some dishwashing liquids may neutralize the effect of the active ingredient of the weedicide by binding chemically with it.
Also, dishwashing liquids may cause excessive foaming to damage spraying equipment.
Non-ionic surfactants, "non-ionic wetters", are recommended to replace dishwashing liquids added to weedicides.
If the weedicide already contains a "built-in" surfactant, there is no need to add more surfactants to the weedicide.
Granular formulations of weedicide require the addition of non-ionic surfactants to work correctly.
However, surfactants may be toxic to fish and frogs, but some "aquatic safe" herbicide formulations are commercially available.
4.4.1 weedicide, (2,4-D), (2,4-dichlorophenoxyacetic acid)
Do not use 2,4-D in school gardens.
See diagram 16.13.11: 2, 4-D.
(2,4-D), 2,4-dichlorophenoxyacetic acid, Cl2C6H3OCH2CO2H
The phenoxyacetic acid herbicides are 2,4-D and 2,4,5-T and its precursor 2,4,5-trichlorophenol (TCP).
The selective herbicide 2,4-D is toxic to broad leafed plants, but less harmful to grasses.
This hormone weed killer 2,4-dichlorophenoxy acetic acid is an aryloxyalkanoic acid known also as a "phenoxy herbicide", including MCPA, mecoprop, triclopyr and 2,4,5-T.
Their actions against weeds resembling those of auxins (growth hormones).
Absorbed 2,4-D is translocated within the plant and accumulates at the growing points of roots and shoots where it inhibits growth.
The principal use is for the control of broad leaf weeds in cereal crops, including wheat, maize, rice, sorghum, grassland and turf areas.
It is also widely used in mixtures with other herbicides to provide weed control in forestry, orchards and non-crop areas, and aquatic weeds.
2,4-D is a WHO Class II "moderately hazardous" pesticide, in the same class as endosulfan, lindane, paraquat and toxaphene.
It has an LD50 of 375 mg / kg in rats with evidence suggesting a similar level of toxicity in humans.
Occupational exposure to 2,4-D has produced serious eye and skin irritation, nausea, weakness and fatigue, and inflammation of nerve endings.
The various chemical forms of 2,4-D can have different toxic effects.
Orthocarboxylic acids, e.g. picloram, can behave in a similar manner and is more potent than 2,4-D.
4.4.2 weedicide, (2,4,5-T), (2,4,5-trichlorophenoxyacetic acid)
Do not use 2,4,5-T in school gardens.
2,4,5-T plant growth regulator, Cl3C6H2OCH2CO2H
(TCDD), 1,4,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-Tetrachlorodibenzo-p-dioxin, C12H4Cl4O2, (and other formulations)
(2,4-D), 2,4-dichlorophenoxyacetic acid, Cl2C6H3OCH2CO2H
See diagram 16.13.11: 2,4,5-T.
4.14.0: Dioxins, "Agent orange", PCBs:
It was used to kill noxious weeds, e.g. privet and blackberry.
At first it caused birth defects in animals and chloracne rash in workers due to a dioxin impurity TCDD (2,3,7,8-Tetrachlorodibenzo-p-dioxin), but this impurity can be controlled.
Production of 2,4,5-T was contaminated with the carcinogenic dioxin TCDD.
Agent Orange was used first by the UK military in Malaysia and later by the US military to defoliate jungle regions in Vietnam.
Abnormal foetal skeletal development, increased foetal mortality and other reproductive effects may be associated with exposure to phenoxy-acid herbicide and their dioxin contaminants.
2,4-D has low soil absorption and a high potential for leachability and 2,4-D residues have been recorded in groundwater and surface water.
Some formulations of 2,4-D are highly toxic to fish.
2,4,5-T,2,4,5-Trichlorophenoxyacetic acid, "Weedone", Acetic acid, (2,4,5-trichlorophenoxy)-555, C8H5Cl3O3.
This herbicide was formerly used for industrial sites, lumber yards and vacant lots, range land and rice, lawns and turf, aquatic use, home use, recreation areas, food crops for humans.
2,4,5-T is used post emergence alone or with 2,4-d for the control of shrubs and trees.
It is also used for girdling, injection or cut stump treatment.
It has been used as a growth regulator to increase size of citrus fruits and reduce excessive drop of deciduous fruit
It has been used for weed control in lakes and ponds at 22-45 kg / ha, and along ditches and irrigation networks.
The use of 2,4,5-T in the United States has been cancelled since 1985.
It is odourless, but is an irritant to eyes, nose, and throat.
The persistence of 2,4,5-T does not exceed one full growing season.
Biodegradation of 2,4,5-T to 2,4,5-trichlorophenol appears to be the dominant removal mechanisms.
2,4,5-T is was one of the most rapidly decomposed herbicides.
2,4,5-T has been qualitatively identified in drinking water.
4.4.3 Acetochlor
Do not use acetochlor in school gardens.
Acetochlor, C14H20ClNO2, herbicide may be carcinogenic, Environmental pollutant.
It is in the chloroacetanilide family of herbicides.
It is used to control annual grasses in corn, (maize), and soybean in USA by inhibiting growth of seedling shoots, applied just before or just after planting.
It is often used in combination with atrazine.
It was a pollutant in Minnesota streams, but to date, (2017), it is not prohibited in USA.
4.4.4 Bifenox
Do not use bifenox in school gardens.
See diagram 16.13.5: Bifenox.
Bifenox, C14H9Cl2NO5, contains chlorine.
It is a contact poison, is fairly safe, but irritates the eyes, and it remains a long time in the soil.
4.4.5 Dalapon
Do not use dalapon in school gardens.
Dalapon, C3H4Cl2O2,2,2-dichloropropionic acid, "Dowpon"
See diagram: 16.13.3: Dalapon.
Dalapon is a herbicide that is used to kill grasses in many crops and drainage ditches.
Dalapon Na is a selective poison that is taken in by the plant and moves through it to kill all parts, including the roots.
It acts slowly over 2-3 weeks.
It is safe to use, but causes irritation to the eyes and skin of some people.
Dalapon can control most annual and perennial grasses, because it will kill every plant it touches.
Dalapon is available as a water soluble powder.
4.4.6 Dinoseb
Dinoseb should not be used in school gardens.
Dinoseb, (2-sec-butyl-4, 6-dinitrophenol), C10H12N2O5, is a dinitrophenol fungicide and insecticide.
It is used as a contact herbicide for post-emergence weed control in cereals, undersown cereals, seedling lucerne and peas.
Dinoseb is also used as an insecticide and miticide.
The use of dinoseb is banned in some countries, because it is known to cause birth defects and sterility if it gets into the drinking water.
However, the EPA in USA determined that the 0.007 mg/L or 7 ppb MCLG and 0.007 mg/L or 7 ppb MCL for dinoseb are protective of human health.
4.4.7 DCMU
DCMU should not be used in school gardens.
DCMU, C9H10Cl2N2O, [(1,1-dimethyl,3-(3,4-dichlorophenyl) urea)], diuron, inhibits photosynthesis.
It is a broad-spectrum residual herbicide and algicide used for pre-emergent and post-emergent control of both broadleaf and grass weeds in agriculture.
It is used to control weeds in pineapples, sugarcane and cotton plantations.
It is also used to control weeds and algae in and around water bodies and is a component of marine anti-fouling paints.
The use of diuron on tropical crops, e.g. tea, coffee, and pawpaw is restricted in Australia.
4.4.8 Ethephon phosphonate, herbicide
Ethephon, 2-chloroethylphosphonic acid, C2H6ClO3P, plant growth regulator, releases ethylene which affects ripening and maturation, and also stimulates the endogenous ethylene production.
White crystalline powder, formulated as a soluble concentrate, is applied as foliar sprays.
4.4.9 Glyphosate, herbicide
Only the teacher can use glyphosate in school gardens.
However, based on a review of current research evidence, the International Agency for Research on Cancer, (IARC), an agency under WHO, upgraded the carcinogenic status of the herbicide glyphosate.
Glyphosate, N-(phosphonomethyl) glycine (C3H8NO5P), (HO)2P(O)CH2NHCH2CO2H, "Roundup", "Rodeo", "Accord", "Zero"
Glyphosate phosphonate, broad spectrum systemic herbicide, may be carcinogenic.
See diagram: 16.13.6: Glyphosate.
1. Glyphosate, gives non-selective control of all grasses and broadleaf weeds, as well as onion weed, bamboo, lantana, blackberry and unwanted trees.
It is used for economical and easy control of weeds when clearing garden beds before planting.
It is non-residual.
Use 200 mL of the concentrated formula to make up to 50 L of spray.
It is absorbed by the foliage then translocated down to the roots to destroy roots and then the whole grass plant.
The first signs after spraying are a gradual yellowing and wilting of the plant, then a complete browning of the entire weed and the death of the root.
It is less effective if the weeds are not actively growing and the dry soil causes the stomata to close, poor leaf cover on weeds, e.g. waxy leaves, rainfall up to 6 hours after application, and if sprayed late in the afternoon.
To allow translocation down to the roots and the chemical to take effect, the weeds should not be disturbed or cut after spraying.
2. Commercial glyphosate products may contain inert ingredients, i.e. anything added to the product other than an active ingredient, e.g. glyphosate 41%,
polyethoxylated tallow amine surfactant 15% and water 44%.
It may contain the contaminant N-nitrosoglyphosate, (NNG).
The registered use status is "General Use".
It can control many difficult weeds, e.g. nut grass, couch grass, Johnson grass, Sorghum halepense, paspalum, kikuyu grass, blady grass, Guinea grass, purslane.
It is used in forestry and noxious weed control to control grasses, herbaceous plants, but not all broadleaf woody plants.
It is absorbed by leaves and prevents production of an essential amino acid and inhibits plant growth.
It is broken down by some plants to mainly aminomethylphosphonic acid.
Do not allow spray drift to contact desirable plants!
It is safe to operators and has no residual activity in the soil, because glyphosate and the surfactants formulations are strongly adsorbed by soil.
However, it remains unchanged in the soil, depending on soil texture and organic matter content, until soil micro-organisms break it down.
Glyphosate and the surfactant are not absorbed from the soil by plants.
It may be harmful to fish, but it does not build up, bioaccumulate, in fish.
It is usually non-toxic to birds, mammals and bees.
In tests in male and female rats, the acute oral LD50 was 4320 mg / kg.
It does not cause genetic damage or birth defects, and no noticeable effect on fertility, reproduction, or development.
4.4.10 MCPA
Do not use MCPA in school gardens.
MCPA, C9H9ClO3, 4-Chloro-2-methylphenoxyacetic acid, 2-Methyl-4-chlorophenoxyacetic acid, (MCPA), S5 poison
See diagram 16.13.11: MCPA.
Phenoxyacetic acids can mimic the natural auxin, plant hormone, indole acetic acid and are not destroyed by the plant.
They can also be used in setting unfertilized fruits and promoting root growth.
When used in excess they can be used as herbicides.
MCPA is used to kill dicotyledon weeds in monocotyledon cereal crops.
Equal amounts are absorbed by weeds and cereals, but the cereals remain unharmed, because of the differences in their growing shoot structure.
4.4.11 Paraquat
Do not use paraquat in school gardens.
See diagram: 16.13.6: Paraquat.
Paraquat, C12H14N2+2, is the trade name for N,N'-dimethyl-4,4'-bipyridinium chloride.
Paraquat is a poisonous dipyridilium compound used as contact herbicide.
Concentrated solutions of Paraquat causes irritation of the skin, cracking and shedding of the nails, and delayed healing of cuts and wounds.
It is a contact fast action poison.
Paraquat is a very dangerous chemical that can kill people if swallowed.
It is not poisonous after touching the clay in soils and there is no persistence in soil.
There should be a 9-day withholding period before harvest.
It controls most broad leaf annual weeds and grasses and works best when weeds are 2-15 cm high.
It is not very effective on perennials with good root systems.
It kills water weeds.
Keep livestock away when spraying Paraquat.
Paraquat is available as water solution.
Mix with water and immediately spray on leaves.
Paraquat, Diquat and Cyperquat are quaternary ammonium herbicides related to cationic surfactants that kill by contact with the plant foliage.
They cannot enter the plant via its roots, because they are very strongly adsorbed onto clay and soil particles.
They are used to kill weeds between crops or just before a crop emerges.
They are toxic to humans.
4.4.12 Weeds of National Significance, (WONS), Australia
African boxthorn, Alligator weed, Athel pine, Asparagus weeds, Bellyache bush, Bitou bush, Blackberry, Bridal creeper, Brooms, Cabomba, Cat's claw creeper, Chilean needle grass, Fireweed, Gamba grass, Gorse, Hymenachne, Lantana, Mesquite, Madeira vine, Mimosa pigra, Opuntioid cacti, Parkinsonia, Parthenium weed, Pond apple, Prickly acacia, Rubber vine, Sagittaria, Salvinia, Serrated tussock, Silverleaf nightshade, Water hyacinth, Willows,
4.5.0 Insecticides
Insecticides are chemicals used to kill eggs, larvae and adult insects by direct contact or by the insect eating the treated plants.
Pyrethrum and neem, Azadirachta indica, are natural insecticides.
Neem oil, Azadirachta indica, Meliaceae
Insecticides based on the nicotine from cigarette butts are now banned.
Insecticides may be harmful to humans and farm animals, and should be used correctly and stored and disposed of safely.
4.5.1 Inorganic chemical insecticides
These chemicals are persistent stomach poisons that kill chewing insects, e.g. caterpillars, but not sucking insects, e.g. aphids, mosquitoes.
Other inorganic chemicals are used as attractants, repellents and synergists.
Inorganic insecticides are usually heavy metal compounds, particularly of lead, mercury, e.g. dimethyl mercury antifungal agent and insecticide, arsenic, antimony.
Also, some are fluoride salts, e.g. NaF, sulfur, polysulfides and borax.
1. Borax (Na2B4O7) is used as a cockroach and ant poison and is harmful to mammals.
Do not use in school gardens.
2. Copper chrome arsenate, (CCA), is used to treat timber, wood: 12.2.2.1
It is used to preserve fence posts and garden furniture giving a green colour.
Such treated timber is safe for normal use, but the sawdust and smoke from burning may contain dangerous levels of arsenic.
(However, the white powder seen on some newly purchased timber is probably harmless sodium sulfate.)
Do not use in school gardens.
3. Copper (II) sulfate and lime is used in Bordeaux mixture.
Do not use Bordeaux mixture in school gardens.
4. Lead arsenate, (PbHAsO4), is a heavy metal compound that is insoluble in water and so not readily absorbed by plants on contact.
The lead blocks essential sites on enzymes and so it is non-specific.
It is toxic to all living systems and extremely persistent.
Do not use in school gardens.
5. Sodium fluoride, (NaF), and cryolite, (Na3AlF6), liberate fluoride ions to precipitate Mg2+ as fluorophosphate, thus affecting magnesium-dependent enzymes.
It is non-specific and toxic to animals.
Do not use in school gardens.
6. Sulfur as elemental sulfur, S, and the soluble lime sulfur, (CaS), experiences aerial oxidation to SO2, to act as a safe fungicide and acaricide.
It has some use as an insecticide.
7. Petroleum oils, petroleum oil spray (PSO) are also "white oil", and "summer oil", and "winter oil" are poisonous to some scale insects.
They are fairly safe to use, but there should be a one day withholding period, before harvest of the sprayed crop.
The classification of petroleum oils is based on the temperature at which 5% of the constituents boil, e.g. C21, C23, C24 oils.
The latter has less phytotoxicity.
The oil droplets on the plant must all join together to kill all the insect pests.
These oils are used in 2 ways:
1. They can control scale insects, e.g. on citrus trees.
2. They can be mixed with other insecticides, e.g. Carbaryl, to spread them better on the plants.
Concentrations: 0.25% = 250 mL oil in 100 L water, 2% = 2 L oil in 100 L water.
4.5.2 Insecticide types, contact, ingestion, systemic
Most insecticides kill insects by attacking the nervous system.
These chemicals can also harm humans, especially children, so they must be used and stored with great care when used in school food gardens.
Insects can take in insecticides in 3 ways:
1. Contact poison
The insecticide touches the body of the insect, which then absorbs it.
2. Ingestion or stomach poisons
The insecticide is sprayed onto plants and the insects eat the plants.
3. Systemic poison
The insecticide is sprayed onto plants that absorb it into the sap.
Then sap-sucking insects suck up insecticide in the sap.
However, most insecticides are taken in by more than one way.
Insecticides may kill the good insects, e.g. bees and ladybirds, as well as the bad insects which eat the crops.
So use insecticides only when the bad insects cannot be controlled in any other way.
If the bad insects are not doing much damage to crops, then do not use insecticides.
4.5.3 Pyrethrin, Plant extract insecticide
Safety: Safety gear should be worn when using pyrethrum.
Follow the dilution rates suggested on product labels.
Pyrethrin, Chrysanthemum monocarboxylic acid pyrethrolone ester, C21H28O3, is a yellow-brown liquid with distinct odour, that sinks in water.
Pyrethrins are two almost identical organic compounds extracted from the pyrethrum flower Chrysanthemum cinerariaefolium.
Pyrethrins have an immediate knock down effect on flying insects, but a second poison may be needed to kill them.
They have low toxicity to mammals.
Allethrin insecticide is an organic compound that is the same as pyrethrin, but made in a factory.
Permethrin is an organic compound that is similar to pyrethrin, but is made in a factory.
Chilli, pyrethrin and permethrin are stomach poisons and contact insecticides.
They are safe to use, but some people are made sick by them.
They are not persistent and there is no withholding period.
These poisons kill most pests quickly, so are called "knockdown sprays".
They also repel insects, stopping them from coming near plants.
They can kill such a wide range of insects that some people spray them only in the early evening when bees have returned to their hives.
4.5.4 Rotenone, derris
Safety: Do not use rotenone, derris, in school gardens.
See diagram 16.13.1: Rotenone.
Rotenone, C23H22O6, polycyclic ketone, toxic, crystalline, odourless, colourless, crystalline, isoflavone, a rotenoid, piscicide, insecticide.
It occurs in Lonchocarpus nicou, dried rhizome and root of Derris elliptica, Pachyrhizus erosus, jicama, also in many Fabaceae.
Rotenone from derris dust, kills aphids, thrips, chewing insects, and is toxic to fish and birds.
Rotenone is an organic compound obtained from roots of the legume Derris and other local bean plants.
This chemical is a contact and stomach poison.
Rotenone can be used to repel insects, control chewing insects and lawn grubs, and as an acaricide.
It is toxic to earthworms and can also affect pigs.
It is effective for short periods only, because it is broken down by oxygen and sunlight.
It is not persistent and must be sprayed every three days.
It does not store well.
This is a good insecticide, but repeated applications are needed.
If applied as "derris dust", the plant leaves must not be too shaded.
Insects are never resistant to this poison.
It can control beetles, weevils, slugs, looper caterpillars, thrips, flies.
Rotenone is also used to poison fish.
Rotenoids are natural substances, with a cis-fused tetrahydrochromeno [3,4-b] chromene nucleus, e.g. rotenone insecticide from Derris elliptica.
4.5.5 Neonicotinoid insecticides
Neonicotinoid insecticides, neonics are systemic insecticides used for seed and pot plant soil treatment, turf spray, foliar spray in glass houses for fruit trees.
They have been blamed for the present decline in the bee population and so have been partially banned in some countries.
15/03/2013 - The European Food Safety Authority gave the most compelling evidence that neonicotinoid pesticides could be responsible for the bee deaths.
Italy has banned some uses of these bee killing pesticides and has already seen it's bee populations come back,
However, Bayer and Sygenta lobbied to prevent a Euro-wide ban, for fears it would harm their global business.
It seems they're close to having the support of the UK, Spain, and Germany, who want to protect their biggest chemical corporations.
Now the issue is coming to a boil.
Just weeks ago, Avaaz delivered a petition signed by over 2.5 million of us to the European Commission, who proposed a ban a day later.
EU parliamentarians and several European governments have announced plans to push ahead with new legislation to ban the pesticides.
Acetamiprid
Clothianidin
Fipronil
Imidacloprid
Thiacloprid
Thiamethoxam
Acetamiprid
Acetamiprid, C10H11ClN4, neonicotinoid insecticide, has population level effects on honeybees by interfering with honeybee reproduction and navigation.
Clothianidin
Clothianidin, C6H8ClN5O2S, neonicotinoid insecticide, is neurotoxic and is highly toxic to bees and other non-target insects.
In 2008 a massive bee die-off occurred in Germany, which was subsequently associated with clothianidin.
Fipronil
Fipronil, C12H4Cl2F6N4OS, neonicotinoid insecticide, is used for indoor and turf pest control.
It causes reduced behavioural function and learning performances in honeybees.
Imidacloprid
Imidacloprid, C9H10ClN5O2, neonicotinoid insecticide, is used in agriculture as foliar and seed treatments, for indoor and outdoor insect control.
It is the most popular neonicotinoid.
It has been found to be highly toxic to bees and other beneficial insects.
It is also toxic to upland game birds, is generally persistent in soils and can leach to groundwater.
It cause disruptions in mobility, navigation, and feeding behaviour.
Thiacloprid
Thiacloprid, C10H9ClN4S, neonicotinoid insecticide, is used to control sucking and biting insects in cotton, rice, vegetables, pome fruit, sugar beet, potatoes and ornamentals.
Low doses are highly toxic to honeybees and fish.
Thiamethoxam
Thiamethoxam, C8H10ClN5O3S, neonicotinoid insecticide, is a systemic insecticide absorbed and transported to all parts of the plant.
If bees eat the pollen, it interferes with nerve cell information exchange, paralysing the insect.
4.6.0 Pesticides definitions
Caution before using pesticides
1.0 Pesticides are chemicals that can kill pests.
Insecticide kills insects, fungicide kills fungus and sometimes bacteria.
Miticide or acaricide kills mites and spiders.
Nematicide kills nematode worms.
Molluscicide kills slugs and snails.
Rodenticide kills mice and rats.
Herbicide or weedicide kills weeds.
2.0 Do not use any pesticides not mentioned in this chapter.
All pesticides are dangerous to humans, especially children, so they must be used and stored with care if they are used in a school food gardens.
Use pesticides only if there is no other way of saving your crop.
If you want to use pesticides always tell the headmaster what you intend to do.
3.0 The rules for using pesticides are as follows:
*. Read the directions on the container before opening.
Make sure that you have the right pesticide for the particular pest.
Make sure that you understand how much pesticide to use.
Make sure that your sprayer and tank is clean and working.
Try it out with water first.
*. Do not breathe in pesticide or spill it on your skin don't smoke or eat when using pesticides.
If you spill pesticide on your skin, wash it off with plenty of soap and water straight away.
*. Wear special protective clothing and wash yourself after spraying.
Always handle concentrates with rubber gloves used only for that purpose.
Wear a work shirt, buttoned down to the wrists, long trousers and boots.
*. Spray on a calm day.
*. After spraying, dig a hole in the bush and pour down it any makeup spray left in the tank.
Wash out the sprayer and pump and pour the washing water down the hole.
*. Store the unused pesticides in a safe place where children cannot enter.
Always use the old container, do not store in a new container, e.g. a drink bottle.
Do not store pesticides near food.
*. The pesticide you will buy will often be in a concentrated form so you must follow a proper mixing procedure.
Always use a plastic measuring cylinder or the special measure some pesticide factories make so you do not guess amounts of pesticide.
Dusts are blown or sprinkled onto plants without using water.
4.0 Mixing procedure for a liquid pesticide:
* Fill sprayer tank half way with water.
* Add measured amount of chemical to sprayer.
* Fill sprayer tank with water.
* Shake the sprayer.
5. Mixing procedure for a powder pesticide:
* Put small quantity of water in bucket.
* Put measured quantity of pesticide powder on top of water, leave until it is thoroughly wetted and then mix into a paste.
* Add water, then add to half filled knapsack as per instructions for liquid pesticides.
If this is not done, some wettable powder will go lumpy and give mixing problems.
4.6.1 Pesticides and herbicides safety
Pesticides are chemicals used for destroying insects or other organisms harmful to cultivated plants or to animals.
Pesticides may be harmful to humans and farm animals and should be used correctly and stored and disposed of safely.
Pesticides can be divided into the following:
1. Baits and traps, e.g. sticky tapes and glues, barrier paints, fruit fly traps, which may be indiscriminate and affect beneficial as well as harmful insects.
2. Contact poisons to be absorbed through the cuticle by spraying or by walking on sprayed fruit and leaves, e.g. pyrethrum, rotenone.
3. Desiccants that wear away the waxy exoskeleton or dissolve the waxy coating on the exoskeleton, e.g. soap sprays and diatomaceous earth.
4. Fumigant gases that must be breathed in by the pest
5. Oils that suffocate small insects, e.g. a mixture of vegetable oils with dishwashing detergents.
4. Stomach poisons that must be eaten, e.g. rotenone and diatomaceous earth.
Pesticides used in schools
The contents below are for information only and are not advice on how any agricultural chemical should be used in a school garden.
Before using any agricultural chemical in a school garden, the supervisor should obtain advice from the Department of Agriculture and should obtain permission from the school principal.
Safety of herbicides, weedicides, and pesticides
Always store keep these chemicals in their original containers!
In many countries, it is against the law to decant them into containers that had contained other substances, e.g. food or drink containers.
A herbicide is a substance used to destroy plants or to slow down their growth.
The formulation is the form in which the pesticide is supplied by the manufacturer for use.
The half-life is the time required for half the amount of substance to be reduced by natural processes.
The LC50 is the concentration in air, water, or food that will kill 50% of the subjects, usually laboratory rats.
Mutagenicity is the ability to cause genetic changes.
Non-target animals or plants other than those that the pesticide is intended to kill.
Persistence is the tendency of a pesticide to remain active after it is applied to the pest or disease.
Residual activity is the remaining amount of activity as a pesticide.
Bees gathering nectar and pollen may be exposed to pesticides or they may carry contaminated pollen back to nests and hives and expose other bees to it.
Copper (II) sulfate solution, dilute sulfuric acid and dinitro-o-cresol can each kill some weeds without causing injury to crops.
S7 Poisons: Nemacur, Bifenthrin.
S6 Poisons: Bromoxynil, Metaldehyde (100%), Hortico blackberry and tree killer, Warfarin, Pindone, Propoxur, Diazinon, Dichlorvos.
S5 Poisons: Ametryn, Dicamba, Pyrethrum, Pyrethrins, Baysol snail and slug bait, Yates Blitzem snail bait, Boric acid.
Unscheduled chemicals: White oil, Lime sulfur spray fungicide, Dipel HG bioinsecticide.
4.6.2 Pesticide safety
Only teachers are allowed to use pesticides.
1. Toxic means poisonous to humans.
2. Safe pesticides: Mancozeb, Maneb, Methoxychlor, Quintozene, sulfur, Zineb.
3. Fairly safe pesticides: Harmful, may cause sore eyes, nose, throat or skin, but there is not much danger if not touched or breathed in.
4. Do not allow students to use Carbaryl, Malathion or Trichlorophon.
5. Dangerous pesticides, toxic.
If these pesticides are breathed in or left on the skin for some time, you may get sick and die.
Only experienced teachers should use these poisons, e.g. Paraquat, Naled, Rotenone, Nicotine, Dimethoate, Methiocarb.
Some pesticides are dangerous if swallowed, but not dangerous if left on the skin.
4.6.3 Pesticide safety, FIRST AID
Any person who becomes ill after using a pesticide should be taken to a doctor or hospital without delay.
Tell the doctor the name of the pesticide used, (active constituent), and show the container.
The person who is sick from pesticide should be left to rest, clothing should be changed and the whole body washed.
The person may need artificial respiration if breathing stops.
If a person has drunk the pesticide, give an emetic to induce vomiting, but only if this is recommended on the insecticide container.
A good emetic is 2 tablespoons of salt in warm water, then push the handle of the spoon gently on the back of the tongue.
The person should be kept head down, face down.
Give the person Ipecac syrup if it is available.
Do not give the person alcohol.
Pesticides on the skin should be washed off with plenty of soap and water, and keep washing for a long time.
4.6.4 Active constituent
Pesticides are usually a mixture of chemicals.
The chemical that kills the pest is called the active constituent.
The other chemicals in the pesticide just make it easier to use and are called the inert ingredients.
Some active constituents are inorganic compounds, e.g. copper oxychloride and some are organic compounds, compounds of carbon.
An organic chloride compound contains a carbon compound and chlorine.
An organic phosphate compound contains a carbon compound and phosphorus.
The name of the active constituent is always written on the label.
Pesticides are made by many different factories in different countries and each factory gives the pesticide its own special name, a trade name, e.g. Glyphosate weed spray: N-(phosphonomethyl) glycine, "Roundup", "Rodeo", "Accord", "Zero", S5 poison.
So it is possible for pesticides with different trade names to contain the same active constituent and be used to kill the same pests.
4.6.5 Chemical pesticides, poisons
None of the chemicals mentioned below should be used in school gardens.
1. S7 Poisons, "Dangerous poison, highly toxic".
Not to be taken.
Keep out of reach of children.
Must be stored in a locked poisons cupboard.
Apply the chemical strictly in accordance with the manufacturer's instructions given on the label, product instruction sheet and the MSDS.
Use MSDS to determine the Dangerous Goods Packing Group.
Use chemical eye protection goggles eye and skin protection when splashes can occur or when spraying, e.g. Bayer Nemacur, Bifenthrin.
2. S6 Poisons "Poison, moderately toxic".
Not to be taken.
Keep out of reach of children.
Must be stored in a locked poisons cupboard.
Apply the chemical strictly in accordance with the manufacturer's instructions given on the label, product instruction sheet and the MSDS.
Use MSDS to determine the Dangerous Goods Packing Group.
Use chemical eye protection goggles eye and skin protection when splashes can occur or when spraying, e.g. Bromoxynil, Diazinon, Dichlorvos,
Hortico blackberry and tree killer, Metaldehyde (100%.), Pindone, Propoxur, Warfarin.
3. S5 Poisons, "Caution, low toxicity".
Apply the chemical strictly in accordance with the manufacturer's instructions given on the label, product instruction sheet and the MSDS.
Use MSDS to determine whether the pesticide is a hazardous substance and / or a dangerous good.
Use eye and skin protection when splashes can occur, e.g. Ametryn, Baysol snail and slug bait, Boric acid, Dicamba, MCPA, Pyrethrum, Pyrethrins,
Yates Blitzem (snail bait), Zero weed spray (glyphosate).
4. Unscheduled chemicals, "very low toxicity".
Use in accordance with the safety instructions on the label, e.g. Lime sulfur spray fungicide, Dipel H G Bio-insecticide, white oil.
4.6.6 Control of pests and diseases
Websites, Plant protection, pests and diseases
| 4.0 Agricultural chemicals
Look at the crops ever day for signs of pests and diseases.
Then be ready to decide what to do about the pests or diseases.
The pest or disease may be harmless or does not do much damage, so either leave it alone or just pick off insects or diseased leaves by hand.
If the pest or disease damages the crop so much that you will not get enough to eat from it, or you cannot sell it, then use pesticide sprays or dusts.
Contact the agricultural field officer and ask for advice.
Clean your spray pump and try it with water first.
Check that you have enough of the right kind of spray.
The only really safe pesticides to use in schools are made of garlic, tomato leaves, chillies, neem, soap, sulfur.
Do not use commercial chemical sprays in schools.
The teacher should do the spraying or supervise an older student very closely.
Keep the students away from the spray.
Do not spray on a windy day.
Wash your hands and face, (using soap), after spraying.
Clean out the sprayer after use so that you do not leave any pesticide in the sprayer.
The five methods of pest and disease control are as follows:
1. Use healthy planting material
2. Select resistant planting material
3. Good land preparation
4. Garden hygiene - burn any crop residues, weeds or useless plants
5. Sterilize soil for seed beds and boxes.
Seeds and cuttings should be clean and free of insects or disease spots.
Imported seeds in sealed silver packets will be free of disease.
Select planting material and seeds from plants known to be resistant to disease.
Prepare the land properly so the plants can grow well.
Dig the soil deeply and dig drains near by so the roots can grow strongly in the drained soil.
Fertilize the plants to provide enough plant nutrients.
Sick plants are damaged more by pests and diseases than healthy plants.
Dig out and burn all plants from the previous crop, weeds, and other stray plants, such as male papaya trees.
If you get rid of all unnecessary plants, then pests and diseases will not live on them ready to attack your crop.
Soil for seed beds or seed boxes can be sterilized by heating the soil in an oil drum all day to kill pests and diseases.
4.6.7 Crop care
Interplanting can help plants to help each other, so use a mixture of different kinds of plants in a garden, for example:
| sweet potato | maize | sweet potato |maize | climbing bean | maize | pumpkin |
If the same kinds of plants are separated from each other by other kinds of plants, it is harder for pests and disease to spread from one plant to plant.
Some plants can help each other by shading weeds or repelling insects, e.g. marigolds will protect plants from nematode worms.
Control by hand: Insects such as caterpillars, diseased plants and parts of plants can be removed by hand and burnt.
Crops should be looked at every day for signs of pests and disease.
Garden hygiene: Do not leave diseased plants in the garden - pull them all out and burn them.
4.6.8 Emulsifying agents
An emulsifying agent is a chemical similar to soap that helps oil and water to mix and form an emulsion.
When two liquids can mix they are called miscible.
Wettable powders, (W.P.), are a mixture of an active constituent, e.g. sulfur, an emulsifying agent, and inert materials, e.g. clay.
Water is mixed with the wettable powder to make a spray solution.
Emulsifiable concentrates, (E.C.), are a mixture of active constituent, an emulsifying agent, and oil.
Water is mixed with the emulsifiable concentrate, (E.C.), to make a spray solution.
Emulsifiable concentrates and wettable powders should never be mixed together.
The label on the pesticide gives information about which other pesticides can be mixed with it.
4.6.9 Fumigants
Fumigants are poisonous gases used to kill pests in stored crops or soil.
They are very dangerous and should not be used in schools.
Some Departments of Agriculture use the dangerous poison ethylene dibromide on agricultural products that carry disease.
4.6.10 Granules
Granules are very small pieces of rock with pesticides stuck to them.
They are usually used when the pesticide has to be put in the soil.
4.6.11 Insect repellents
See diagram 16.13.8: Deet, DMP.
Natural insect repellents contained strong smelling oils, e.g. citronella, that repel insects after contact with the repellent.
The most effective insect repellents is deet, NN-diethyl-m-toluamide, C12H17NO.
Also, DMP, dimethylphthalate, (C2H3O2)2C6H4, is an effective mosquito repellent, but it dissolves the plastic in watch glass and spectacles.
Other effective repellents are E-Hex, ethyl hexanediol, and Indalone, butyl 3,4-dihydro-2,2-dimethyl-4-oxo-2H-pyran-6-carboxylate!
The best repellent for bush flies and sand flies is di-n-propyl isosinchomeronate with the addition of the pyrethrum synergist
N-octyl bicycloheptenedicarboximide, NN diethyltoluamide, di-N-propyl isocinchomeronate.
An attractant for pantry moth is "biolure", (2,E)-9,12-tetradien-1-yl acetate.
Java oil contains geraniol and citronellal.
4.6.12 Integrated pest management, (IPM)
Try to adopt an IPM approach to the control of pests on school farms.
IPM is a process of selecting a range of control strategies and using them jointly in the removal of agricultural pests.
Pest control methods that do not rely on the use of chemicals include the following:
* Physical or mechanical control, e.g. hand picking, fly swats, mouse traps, fly screens, using light traps, using ultrasound, hand chipping of weeds.
* Cultural or managerial control, e.g. farm hygiene, crop rotation, companion planting, adjusting time of planting / harvest, use of sealed storage.
* Genetic control, e.g. the use of plants that are resistant to the pest.
* Exclusion, e.g. fences to keep out rabbits, isolation of sick animals from a healthy herd, inspection of animals before allowing entry to a school farm.
* Biological control, i.e. use organisms to reduce activities of pests, e.g. control of cabbage white butterfly with bacterium Bacillus thuringiensis.
Bt, Bacillus thuringiensis, is a naturally occurring soil bacterium, an insecticide, which kills juvenile insects, mainly caterpillars and beetle larvae that consume it.
The gene for Bt is used in GM, genetically modified, crops.
Also, Bacillus subtilis, suppresses the fungus Alternaria helianthi seedling blight of sunflowers
4.6.14 Mancozeb
Do not use mancozeb in school gardens.
Mancozeb, ethylene bisthiocarbamate, (EBDC), a dithiocarbamate, (C4H6N2S4Mn)x.Zny, (a combination of Maneb and Zineb), e.g. Pestanal, Dithane, protective fungicide, against many fungal diseases, including potato blight, leaf spot, downy mildew, and used for seed treatment of cereal grains.
It is low risk to humans, but irritates eyes, skin, respiratory tract, and is toxic to aquatic organisms.
4.6.15 Maneb
Do not use maneb in school gardens.
Maneb, manganese ethylene bis(dithiocarbamate (C4H6MnN2S4), fungicide, controls blight, leaf spot, downy mildew, marine pollutant.
4.6.16 Persistence
Some pesticides and weedicides remain active for a long time, even in the soil.
The time they remain active is called "persistence".
Pesticides that persist for a long time may be dangerous, because their poisonous properties may affect later insects, animals and crops.
4.6.17 Resistance to pesticides
It often happens that pesticides do not kill all the pests, because some get sick, but remain alive.
Surviving pests may produce offspring which will not be affected by the pesticide, because they have developed resistance to this pesticide.
So it is not wise to always use the same pesticide, but change the pesticides used from time to time.
So when you use up all of one type of pesticide, try using another type of pesticide.
4.6.18 Surface-acting agents
Surface acting agents are chemicals that may already be added to the pesticide or that can be added to the pesticide.
They include detergents, soaps, wetting agents, spreaders and stickers.
These chemicals spread the pesticide over the plants better and may make them stick to the plants.
The label on the pesticide will tell you whether to mix with a surface active agent, a surfactant.
There are many commercial surface active agents or use any washing detergent.
4.6.19 Synergists
Synergists are chemicals added to pesticides to make them more poisonous, e.g. piperonyl butoxide makes the insecticide pyrethrum more poisonous.
4.6.20 W / V, W / W
W / V This means weight per volume or the weight of active constituents in a certain volume of pesticide.
So 30% W / V emulsifiable concentrate means 30 grams of active constituent in every 100 mL of the emulsifiable concentrate.
This may also be written as 300 g / L (grams per litre).
W / W means weight per weight or the weight of active constituents in a certain weight of pesticide.
So a 50% W / W wettable powder means 50 grams of active constituent in every 100 grams of wettable powder.
This may also be written as 500 g / kg (grams per kilogram).
4.6.21 Withholding period
This is the recommended time between spraying the crop and harvesting the crop, so that people will not be made sick by eating any pesticide remaining on the plants.
Make sure that crops that have been sprayed are not harvested within the withholding period.
A sprayed crop must be washed thoroughly before being eaten.
4.7.0 Sprays, dusts, white oils
The sprays below may be used in school gardens.
1. Basil leaf spray deters insects.
2. Compost that is mature is soaked in water, filter water and use as a spray.
3. Eucalyptus leaf spray deters insects.
4. Lettuce leaves, boil and spray on cabbages, cauliflower, Brussels sprouts to deter white cabbage moth.
5. Lime sulfur (it may stain paint)
6. Nettle leaf spray deters insects
7. Pepper spray
7a. Red peppers crushed in a household blender, strained + rubbing alcohol + half cup of hot water
7b. Use 2 tablespoons of hot pepper sauce + drops of biodegradable dish soap, 1 litre of water and use a spray bottle.
9. Sabadilla lily for control of stink bugs
10. Seaweed sprays control fungus diseases
11. Soap sprays, using pure soap not detergent, break down waxy layer of exoskeletons on small insects.
12. Spearmint leaves spray
13. Talcum powder for control of corn ear worm
14. Tomato leaves crushed in a household blender, strained + corn starch + water.
Crushed tomato leaves contain Solanine.
Tomato leaf spray kills aphids and mites.
15. Dusts are best applied either in a proper duster or a tin with a stocking over the end.
4.7.1 Chilli spray
Chilli spray may be used in school gardens.
Chilli Project
1. Chilli spray contain an organic compound that repels insects.
Grind chillies, but be careful not to put it in your eyes, and add soapy water or detergent as a sticker.
Wear gloves and spray on leafy vegetables.
Repeat the spray regularly.
Label and store in a safe place away from children.
The spay deters ants, aphids and small soft body insects.
2. Use 50 small hot chillies or chilli powder or chilli paste, 2 litres of water, 5 g of pure soap flakes dissolved in hot water or 5 drops of liquid soap.
Put the chillies and 1 litre of water in a household blender, strain the puree mixture, add the soap and 1 litre of water.
Spray the mixture without dilution.
Label and store in a safe place away from children.
4.7.2 Garlic spray
Garlic spray may be used in school gardens.
Garlic, (Allium sativum var. sativum), Amaryllidaceae
1. Soak garlic and onion in hot water.
Garlic oil may be effective against the larvae of mosquitoes and houseflies.
2. Use 3 crushed garlic cloves, 1 tablespoon (15 - 20 mL), of vegetable oil, 1 litre of water, 1 teaspoon of liquid soap.
3. Mix 3 cloves of macerated garlic + 5 mL of household detergent + 500 mL of water.
Use solution as a spray to deter aphids, slugs, and beetles.
4. Slice 100 g of garlic cloves and add 2 teaspoons (30 mL), of paraffin oil.
After two days, add 600 mL of water and 1 teaspoon liquid soap detergent.
Strain this concentrate into a plastic bottle.
For spraying, add 1 teaspoon of this concentrate to 600 mL of water.
The spry kills different pests including cabbage moth.
5. Add 3-4 cloves of minced garlic into two teaspoons of mineral oil.
Leave overnight then strain the garlic out of the oil.
Add the oil to half a litre of water, + a teaspoon of biodegradable dish soap.
Dilute the mixture before use: 2 tablespoons of garlic oil mixture + 200 ml water.
Garlic oil repels whiteflies, aphids, and beetles.
4.7.3 Nicotine spray
Nicotine spray should not be used in school gardens.
Nicotine, C10H14N2
Tobacco plant, (Nicotiana tabacum), Solanaceae
Tobacco water, cigarette, butt water, colour of brown tea, kills underground pests.
Nicotine is an organic compound obtained from the leaf of the tobacco plant.
It can be made by putting non-filter cigarette, butts in hot water.
This poison is a stomach poison for many insects.
Nicotine chemical is too dangerous for use in schools.
4.7.4 Diatomaceous earth absorbacide
Diatomaceous earth may be used in school gardens.
1.0 Class Bacillariophyceae (Diatomophyceae), (Phylum Bacillariophyta), diatoms
Diatomaceous earth is sold as a fine dusting powder that kills insects by absorbing the protective coating of wax and oil.
Also, it is rich in minerals, so it both protects and feeds plants when added to garden soil.
4.75 Sprayers and dusters
1. The chemicals used in agriculture may be applied as granules, dusts, or sprays.
Granules are put into the soil, dusts are blown onto crops so do not need water.
Granules can be spread by hand or you can buy a granule applicator or spreader.
Sprays must be made up by mixing the chemical concentrate with water and sometimes a wetting agent.
The cheapest dusters are the plunger type, which look like a bicycle pump.
There are also larger and dearer rotary hand dusters.
The simplest duster is made by cutting the bottom out of an opened fish tin and then put it in an old sock.
2. The 3 types of sprayers:
2.1 Slide action sprayers
They are the cheapest.
They are similar to the common fly spray.
They contain up to 5 litres of spray.
It is very tiring to use them for a long time.
They do not control the pressure of the spray.
These sprayers can be used in school kitchen gardens.
2.2 Continuously pumped knapsack sprayers
They are worn on the back or over the shoulder.
They should give a continuous spray if you pump them slowly and evenly.
They usually contain 10-15 litres of spray.
They may be made of brass or plastic.
Brass sprayers are tough, but heavy.
Plastic sprayers are light, but can be damaged if dropped or left out in the sun.
Plastic knapsack sprayers are the best type to use in school field gardens.
2.3 Compression type sprayers
After filling these sprayers, they are pumped up to a high pressure.
Then they can be used without further pumping.
These sprayers are probably too expensive for schools.
3. Care and maintenance for a knapsack sprayer
* Wash out the sprayer tank, hose and nozzle with clean water.
* Clean the jet, which is the little hole at the end of the nozzle the spray passes through.
Check that it is the right size for the job.
Be very careful not to lose this little jet!
* Read the instructions on the chemical container carefully, then measure out the amount of chemical you need for the job.
* Add clean water to the sprayer until it is half full.
* Put the measured amount of chemical into the sprayer, by using a graduated cylinder. and not guessing the amount of chemical concentrate.
* Wash the chemical measure and put this water into the sprayer, then fill the sprayer with water.
* Do not spray in the wind or rain.
* When spraying walk evenly at about one pace each second to give each plant an even covering.
* When finished, dig a hole in the bush and tip out all the unused spray into it.
* Wash out the sprayer, hose and nozzle and tip all this water down the hole.
* Remove the hose and nozzle then hang them upside down on the wall inside a lock up shed.
4.7.6 Oil sprays
The sprays below may be used in school gardens.
1. One cup vegetable oil to half a cup of water.
2. Scale, aphids, smooth skinned caterpillars, mites and young grasshoppers suffocate when their bodies are covered with white oil.
Oil sprays also deter the citrus leaf miner.
In a blender, combine 2 cups of vegetable oil with a cup of dishwashing liquid.
Blend it up until it is mixed well.
Store this concentrate in a jar.
Label it and include the dilution rate on the label.
Dilute 1 tablespoon in a litre of water, mix it well and spray the pest as well as both sides of the foliage thoroughly.
Always follow this dilution rate, because you can burn the foliage if it is too strong.
Do not apply it in hot weather.
Do not use it on plants with hairy foliage, ferns, palms and cycads as this can also cause leaf burn.
Never use it on your trees in winter.
3. Use 500 mL vegetable oil, 1 cup pure liquid soap, blend thoroughly in a mixer, store in a labelled jar in a cool place.
For use, dilute 1 tablespoon (15 - 20 mL), of the mixture with 1 litre of water.
Oil sprays can suffocate mites, scale insects and other small soft-bodied insects and deter leaf miners and small grasshoppers.
The spray may not work on hairy leaves.
Do not use the spray during very hot weather.
4. Use 1 teaspoon (about 5 mL), liquid dishwashing detergent (as a wetting agent), 1 cup (about 200 mL) vegetable oil, 1 quart about 1 litre) tap water, for mites, aphids.
It is a contact insecticide so it must contact all the insects.
Test it first on small leaves, because it may cause leaf tip burn.
Some gardeners prefer soap suds, using soft potassium soap, instead of dishwashing detergent.
Some gardeners add ammonia or vinegar to attack scale insects.
5. Use 2 cups vegetable oil + 1/4 cup of dishwashing detergent in blender for the concentrate, then use 1 tablespoon, (15 - 20 mL), to 1 litre of water.
Spray both sides of leaves until all leaves are dripping wet.
6. Use 160 mL dishwashing liquid + 15 mL glycerine in 4 L water.
7. Use 4 parts vegetable oil, e.g. canola + 1 part dish-washing detergent, blend in electric blender until homogeneous, dilute 1:50 with water, spray from above and below.
8. Use 750 mL canola oil + 45 mL detergent, e.g. "Sill" + 1, 250 mL water.
9. Use 300 mL canola white oil + 300 mL vinegar + 300 mL water 4 + "Alginox" to kill algae, and spray during overcast weather or in the evening.
10. Use commercial white oil for scale insects, aphids, smooth skinned caterpillars, mites, young grasshoppers, citrus leaf miner, mealy bugs, mites on roses, ornamentals, citrus, fruit trees.
White oil contains petroleum distillates oil in dewaxed light paraffin emulsifiers.
Spray white oil every 4 weeks.
Do not store above 35oC.
Do not use on citrus late autumn / winter and use not later than one day before edible harvest.
Small insects suffocate when bodies are covered with white oil.
However, white oil is more expensive than the above general contact sprays.
11. Use 45 mL sodium bicarbonate + 35 ml white oil + 4.5 litres of water, spray weekly, saturate leaves to runoff: aphids, black spot, powdery mildew.
12. Use 5 mL of cooking oil + 5 mL household detergent + 500 mL of water.
Use the solution as a spray to control sooty mould.
13. Use 4 mL of sunflower oil + 10 cc sodium bicarbonate + 1 drop household detergent + 1 litre of water.
Use the solution as a spray to control black spot on roses.
4.8.0 Insect pests collection
Before starting to teach this and the next lesson, make a collection of pests and diseases from your garden.
They can usually be preserved in methylated spirits.
Also, collect diagrams of different pests.
Make sure that your garden is a good example of pest and disease control.
Check your spray equipment and pesticides.
A field visit may be useful for this lesson.
Show the students the examples of pests and diseases that you have collected from the garden.
To obtain the greatest possible production and cash income from your crops you must control loss by pests and diseases.
Pests are animals that eat your crops or infect your crop plants with diseases.
Pests may live in the ground, be attached to infected plants or may fly or walk to your crop.
Diseases are any change in the plant such as spots or holes in the leaves, wilting of the plant, rotting of the living plant.
They are caused by living things that may be so small that they cannot usually be seen by eye.
Diseases are carried by wind and water, infected plants, and pests.
4.8.1 The main pests of crops:
1. Nematode worms or eel worms: They are small worms pointed at both ends and have S-shapes.
They attack plant roots and may live in lumps on the roots.
They attack papayas, tomatoes, and bananas.
Killing nematodes or eel worms in the soil is very difficult.
| Bulb and stem nematode Ditylenchus dipsaci on onions | Leaf nematodes Aphelenchoides spp., on strawberries |
2. Snails and slugs: Slugs are like snails with no shell.
They eat plant leaves and stems.
They can be controlled by picking off by students or by spraying with "Cuprox".
3. Spiders: Tiny red spiders called mites attack the leaves of beans and eggplant.
A chemical that kills them is called an acaricide, e.g. wettable sulfur.
| Broad mite Polyphagotarsonemus latus on eggplants | Bulb mite Rhizoglyphus echinopus on garlic | Bunch mite Brevipalpus lewisi on grapes |
| Bean fly Ophiomyia phaseoli on French bean |
They attack cabbages, tomatoes and beans.
| Cabbage white butterfly Pieris rapae on cabbages |
4. Mole crickets and grasshoppers: They attack Chinese cabbage and lettuce.
| Black field cricket Teleogryllus commodus on pasture | Mole crickets Gryllotalpa spp. on vegetables |
7. Beetles: Beetles have hard shiny outer wings
| Pumpkin beetle Aulacophora hilaris on pumpkins | Rhinoceros beetle Xylotrupes gideonon on coconut palms |
8. Bugs: Bugs have soft wings, e.g. vegetable bugs.
| Golden mealybug Nipaecoccus aurilanatus on bunya pine |
9. Rats: They eat root crops and fruit.
4.8.3 Rodenticides
4.8.2 Silverleaf white fly
Silverleaf white fly, sweet potato white fly, Bemisia tabaci, attacks sweet potato, tomato, cucumber, eggplant, poinsettia, okra, bean.
It sucks nutrients from phloem or lower leaf surfaces leaving chlorotic spots and withered leaves.
It produce a sticky substance, "honeydew", on which sooty moulds can grow, which reduce light to plant.
It is also vector for plant diseases, e.g. lettuce yellows virus, tomato yellow leaf curl virus, African cassava mosaic, and cassava brown streak virus.
There is no easy way to control it except by removing weeds near the crop.
4.8.3 Rodenticides
23.2.18 Rodents, rats
Only the teacher should use rodenticides.
Coumarin
Rodenticides, commonly called rat poisons, are chemicals used to kill rodents, i.e. rats and mice.
Rodenticides are poisonous and may harm people.
Great care needs to be taken when using rodenticides to kill pests.
Rodenticides should be used correctly and stored and disposed of safely.
4.9.7 Nodules and galls
4.13 Rhizobium in root nodules
Agrobacterium
Nodules and galls are the result of growth stimulation by various agents: bacteria, viruses and insects.
They may be beneficial, as are the root nodules caused by Rhizobium, a bacterium that fixes nitrogen when inside the root where a symbiotic association occurs.
Some types are formed by parasitic associations, e.g. insect galls, or are pathological, e.g. sunflower gall and virus infections.
Plants respond to the presence of the bacteria by producing auxins and kinins that are responsible for the abnormal cell division that lead to the swelling.
Use young sunflower plants, half of which, about a week ago, received an inoculation of bacteria, Agrobacterium tumefaciens, which cause galls.
Note normal growth and deformity caused by the bacteria.
Preface
Before teaching this project, discuss the content of the lessons with a field officer of the Ministry of Agriculture, and get advice on planting material, planting distances, site for planting, approved mulch, composting, and control of pests and diseases.
Use only the procedures, agricultural chemicals and insecticides recommended by the local field officer of the Ministry of Agriculture.