Insecticides And Fungicides A to Z

Alum. There are many alums, but as a pesticide it is aluminium sulphate that is used. It is used primarily for killing slugs and snails but can also be used to make plants or buds distasteful to birds. For killing slugs it can be applied dry, sprinkled in powder form round plants and renewed fairly often, or as a heavy drench by dissolving 4 oz. in 1 gal. of water and applying it from a watering-can or sprayer. To deter birds the same solution is sprayed finely on to plants. Adding a little household detergent to the water helps to spread it evenly and more effectively.

Azobeuzene. An insecticide obtainable in proprietary formulations ready for use according to manufacturer’s instructions. It is chiefly valuable for killing red spiders under glass, for which purpose it is used either as an aerosol (a suspension in air of very minute particles produced as a rule by forcing the azobenzene through a fine nozzle by means of the pressure of carbon dioxide released from a ‘sparkle bulb) or as a smoke. While treatment is being carried out, the temperature of the greenhouse should be maintained near 70° F. Azobenzene can damage some plants if used in bright sunshine or after plants have been sprayed with anything which contains oil.

BHC. The letters stand for benzene hexachloride. The best form is gamma-BHC and when 99% pure, this is known as lindane. It can be obtained in various proprietary forms for wet or dry application and also in smoke generators, for fumigating under glass, and all these should be used strictly in accordance with manufacturer’s instructions.

Dusts are suitable for use against ants, earwigs, flea beetles, leather-jackets, mushroom flies, springtails and wireworms. Sprays can be used against any of these, also aphids, apple suckers, cabbage root fly, capsid bugs, raspberry cane midge, sawflies, symphalids, thrips and woolly aphid.

Crude BHC has a strong tainting effect and should not be used on blackcurrants or as a soil insecticide where any root crops are to be grown. Lindane (gamma-BHC) has far less tendency to taint, but even so cannot be recommended for potatoes, nor for grapes or blackcurrants after they have blossomed.

Edible crops should not be harvested for two weeks after use of uric dusts or sprays or for two days after use of BHC smokes.

Borax. Sometimes used to kill ants and cockroaches for which purpose powdered borax is well mixed with an equal quantity of castor sugar and sprinkled where ants are seen.

Bordeaux Mixture, The most generally useful fungicide .against potato disease (phytophthora).

STRONG SOLUTION: For use against potato disease (blight) and on other strong-leaved plants not liable to be scorched.

9 oz. of copper sulphate.

6 oz. of quicklime.

5 gals. of water.

STANDARD SOLUTION: For use against apple and pear scab and as a general fungicide.

6 oz. of copper sulphate.

6 oz. of quicklime.

5 gals. of water.

REDUCED SOLUTION: For use on tender-leaved plants liable to be scorched.

-71 oz. of copper sulphate.

9 oz. of quicklime.

5 gals. of water.

Dissolve the copper sulphate in 4 gals. water. Put the quicklime in another vessel and slake it by adding water, a little at a time.

Make up to 1 gal. with water; add to the copper sulphate solution slowly and stir well. Use at once. Wooden or enamelled vessels should be used for mixing. It is advisable to test the strong solution with litmus paper before using. If blue paper turns pink, more lime should be added, till there is no such reaction.

Bordeaux mixture can also be purchased in powder or paste form ready for mixing with water, when manufacturer’s instructions should be consulted regarding strength.

Burgundy Mixture, A little more powerful as a fungicide than Bordeaux mixture and often used instead of it.

This mixture is found especially serviceable against rusts.

8 oz. of copper sulphate.

10 oz. of washing soda.

5 gals. of water.

Dissolve the copper’ sulphate in 5 gals. of water and the washing soda in the other gallon. Pour the washing soda solution into the copper sulphate solution, stirring well. Prepare mixture in wooden or enamel vessels. Use at once.

Calomel. This is the commercial name for mercurous chloride. It is usually supplied as a ready-prepared dust containing 4% calomel. It is used to kill the eggs of the cabbage root fly and onion fly, and is scattered for about 2 in. on both sides of each row of seedlings at the rate of 1 lb. to 60 yd., or round individual plants at about 1 oz. to 10 plants. The most effective time for brassicas is when they have made the second or third rough leaf; for onions when the seedlings are 11 in. high. Second applications may be given 10 to 14 days later. May and June are danger periods. Calomel dust well watered in also controls many lawn diseases.

Calomel is also used to check club root, for which purpose a little of the dust is sprinkled into each hole prepared for a brassica plant or, alternatively, the roots of the plants are dipped into a thin paste prepared by mixing calomel dust with water. Calomel dust can also be raked into the seed bed prior to sowing.

To control onion white rot 4% calomel is dusted along the seed drills at 1 lb. to 50 yd. Calomel can also be used as a dip for diseased gladiolus corms. 1 oz. of pure calomel in 1 gal. of water; immerse corms for 5-10 minutes, keeping the mixture stirred so that the calomel does not settle.

Captan. A synthetic chemical used as a fungicide. It is particularly recommended for the control of apple and pear scab as it does not scorch leaves or russet or crack fruits; it is also used to control rose black spot. It is purchased as a powder which must be mixed in water according to the manufacturer’s instructions and kept stirred while it is applied as a spray. Its effect does not last long and so it may be necessary to spray every 10 to 14 days from April to August to secure complete control. Captan is also used in seed dressings to protect seedlings from damping off and other soil-borne diseases.

Captan is harmful to fish.

Carbaryl, A synthetic insecticide effective against a fairly wide range of pests including caterpillars, codling moths, cutworms, leather-jackets, flea beetles, weevils, scale insects, white flies, thrips, pear leaf blister mite, earwigs and woodlice. It is available as a wettable powder for mixing with water according to manufacturer’s instructions. The mixture should be continually agitated while the spray is being applied. It is also available as a dust ready for use and this is commonly called sevin dust. Carbaryl is harmful to bees and fish, so should not be used when plants are in flower and should be kept out of streams and ponds. It is moderately persistent and should not be used with alkaline mixtures such as Bordeaux or lime sulphur. When used on edible crops at least one week must elapse before they are harvested.

Caustic Soda. A winter fruit-tree cleanser which has been practically superseded by tar-oil wash. The old formula was as follows:

1 lb. of caustic soda (98% purity).

5 gals. of water.

Dissolve the soda in I gal. of water, stirring occasionally. Add the remainder of the water and stir again. Apply in the form of a coarse spray. It must only be used in winter when trees are dormant, and must be kept off skin and clothes.

Cheshunt Compound, A soil fungicide used for the prevention or check of damping-off disease, collar rot, and other soil-borne diseases. The formula for mixing is as follows:

2 parts of finely ground copper sulphate.

11 parts of ammonium carbonate (fresh).

Mix the copper sulphate and ammonium carbonate thoroughly and store in a stoppered glass jar for at least 24 hours. Dissolve 1 oz. of the dry mixture in a little hot water and add to 2 gals. of water. The solution should be used at once. It may be watered freely on the soil in which plants or even seedlings are growing.

This preparation can also be purchased ready for mixing with water.

Chlorbenside. A synthetic acaricide used to control red spider mite both outdoors and under glass. It kills the eggs but not the mites, so is a little slow in action, but after a few weeks does give complete control. It is purchased as a wettable powder to be mixed with water as advised by the manufacturer and applied as a spray. For fruit-tree red spider, one application in May or early June is usually sufficient. On other plants it can be used immediately red spider mites are observed, and further applications can be given if necessary.

Chlordane. This is a synthetic chemical used at present for the control of worms and leather-jackets in lawns. It is very persistent and will remain effective for at least a year. It is supplied as a liquid to be mixed with water, and can be applied with a watering-can, or sprayer; it must penetrate the turf thoroughly. The best times to apply it are the spring or autumn. It is poisonous to warm-blooded animals and should not be used on seedling grass or turf less than three months old. Livestock should not be allowed on treated turf for two weeks.

Copper. Various formulations of copper compounds, including copper oxide and copper oxychloride, are sold as ‘copper fungicide’ or under trade names. They may be employed for any of the purposes for which other copper sprays, such as Bordeaux or Burgundy mixtures,, might be used. The manufacturer’s instructions regarding strength and application must be followed. Soap must not be used as a spreader, but saponin etc. c. n be substituted.

Copper Sulphate Wash. A very powerful fungicide for winter use against fungi which are difficult to kill by other means, such as those causing rose rust and black spot.

1 oz. of copper sulphate.

1 gal. of water.

Dissolve the copper sulphate in the water and stir well. This

wash must be used only in winter when all leaves have fallen.

Cresylic Acid. A powerful soil sterilizer for use against many insects and fungi. One gallon of 97 to 99% purity cresylic acid is diluted with 100 gals of water. This is applied with a water-pot; 7 gals. is sufficient for about 1 sq. yd. of soil. Treated soil should be covered with tarpaulins or wet sacks for a day or so to trap fumes, after which it should be uncovered and left for from three to five weeks before use. For cleansing woodwork in glasshouses, it should be applied from a spraying machine with as much force as possible and the house closed down for 24 hours. No plants must be cultivated in the house for at least a month.

Dazomet, A soil sterilizer used to control certain eelworms and some soil-borne diseases. It also checks growth of weed seedlings and couch grass. It is available as a proprietary dust to be sprinkled on the soil and immediately worked in to a depth of about 1 ft. The usual rate is 1 lb. per 100 sq. ft., or 7 oz. per cu. yd. of potting soil but manufacturer’s instructions should be followed. Treated potting soil should be covered with sacks or tarpaulins for three weeks, then uncovered and turned several times over a period of four or five weeks to allow fumes to escape.

Nothing should be planted or sown on treated soil for at least eight weeks.

DD. An abbreviation for dichloropropane-dichloropropene, a chemical used to kill eelworms in the soil. It is a liquid and can be poured into dibber holes 6 in. deep and 12 in. apart, 1/8 fl. oz. DD per hole, but because the chemical is strongly irritating to skin, eyes, nose and mouth, this can be a somewhat hazardous undertaking. A far better method is to use special injection apparatus. DD must not be used near growing plants and treated soil must be left vacant for at least six weeks.

DDT. (Dichloro-diphenyl-trichloroethane). This powerful synthetic insecticide is not available in the pure state, and even in proprietary formulation its use is limited because of its extreme persistence. It is prepared as a dust to be applied dry, wettable powder for use as sprays, oil emulsions, also for liquid application after dilution with water and in smoke generators for fumigating under glass. In all cases manufacturer’s instructions regarding strength should be obtained, as different brands may vary greatly in this respect. It is particularly effective against weevils (including the apple-blossom weevil), beetles (including flea beetles), caterpillars, thrips, flies (including the mushroom flies), scale insects, white fly and mosquitoes.

Demeton-S-methyl. An organo-phosphorus insecticide used to kill aphids, red spider mites, apple and plum saw-flies, leaf hoppers and woolly aphid. It is poisonous to warm-blooded animals, including man, so proper care should be taken in handling the concentrated chemical and rubber gloves and face shield worn when applying it.

This insecticide is systemic, being absorbed by the plant through its sap and being distributed throughout the whole plant. It should not be used on edible crops within three weeks of harvesting, nor on brassicas of any kind after the end of October. It is poisonous to bees and fish, and should not be used on plants that are in flower or are about to flower, nor should it be allowed to get into ponds or streams. It is sold as a liquid for dilution with water and application as a spray, and also as an aerosol much diluted and ready for immediate use, following manufacturer’s instructions.

Derris, An insecticide that is effective against many pests including aphids, leaf hoppers, thrips, caterpillars of many kinds, apple-blossom weevil, pea and bean weevil, raspberry beetle, gooseberry sawfly, flea beetles and red spider mites. Though relatively harmless to human beings, warm-blooded creatures and bees, it is recommended that at least one day elapse between use on edible crops and harvesting. It is very poisonous to fishes.

Derris is available as a dust, ready for immediate use, and as a liquid to be diluted with water and used as a spray according to manufacturer’s instructions. The effectiveness of derris depends on the percentage of rotenone it contains and this may diminish with age.

Derris can be mixed with lime sulphur or Bordeaux mixture, but in that case soft soap must not be used. One of the alternative spreaders should be substituted.

Diazinon. An insecticide used primarily to kill aphids, capsid bugs, leaf miners, thrips, red spider mites, mealy bugs, scale insects, springtails and mushroom flies. It is poisonous to warm-blooded animals, including man, but provided reasonable care is taken in handling, no special clothing need be worn. It should not be used on cucumbers or tomatoes in early spring. Special care should be taken if other chemicals of the organo-phosphorus group, to which diazinon belongs, have been used, as accumulation of these chemicals within the body can be harmful.

It is available as an aerosol, as a liquid for dilution

with water, in granular form and as a wettable powder. In all cases manufacturer’s instructions must be followed. Edible crops should not be harvested for two days after treatment with diazinon aerosol or for two weeks after treatment with any of the other formulations.

Dichlofluanid, A fungicide used primarily to control botrytis (grey mould) on strawberries, currants etc., and black spot on roses. It should not be used on strawberries grown under glass or polythene. At least two weeks must elapse between use on edible crops and harvesting. It is harmful to fish. Dichlofluanid is available as a wettable powder to be stirred into water as recommended by the manufacturers and kept agitated while being applied as a spray.

Dichloran, A fungicide primarily used to control botrytis on cyclamen, lettuce and tomato and tulip fire. It is available as a proprietary dust for application direct. At least three weeks should elapse before any treated edible crop is harvested.

Dicofol. An acaricide used to kill red spider mites and their eggs. It is available as an aerosol for immediate use and also as a liquid to be diluted with water and applied as a spray according to manufacturer’s instructions. It should not be used on seedlings or young plants under glass before mid-May or on plants while they are exposed to strong sunshine. Edible crops sprayed with dicofol should not be harvested for seven days or for two days after treatment with dicofol aerosol.

Dimethoate. A systemic insecticide, i.e. one that is absorbed into the sap of plants. It is used primarily to control aphids, apple and pear sucker, plum sawfly, woolly aphid and red spider mites. It is available as a liquid for dilution with water and as a wettable powder which must be kept agitated when mixed with water. All should be used accord ing to manufacturer’s instructions. Edible crops treated with dimethoate should not be harvested for at least one week. Special care should be taken if other chemicals of the organophosphorus group, to which dimethoate belongs, are being used, as accumulations of these in the body can be harmful. Dimethoate should not be used on chrysanthemums.

Dinocap. A fungicide used primarily to control powdery mildews on many plants, though it will also help to control red spider mites. It is available as a liquid for dilution with water or as a wettable powder to be kept agitated when mixed with water and applied as a spray. Dinocap is not very poisonous to warm-blooded animals, including man, but care should be taken not to inhale it nor to get the concentrated chemical on the skin.

Edible crops treated with dinocap should not be harvested for at least one week. It should be kept out of pools and streams as it is harmful to fish.

DNOC, (Dinitro-ortho-cresol). This insecticide has been added to petroleum oil in certain proprietary preparations to produce a winter wash for fruit trees which proves effective against the overwintering stages (including the eggs) of capsid bugs, apple sucker, aphids, winter moth caterpillar, tortrix moth, raspberry moth, scale insects, apple-blossom weevil and red spider mites. The wash is applied as a heavy spray while the trees are dormant (December—late February). The usual formula is 21- to 3 pints of combined petroleum and dinitro-ortho-cresol to 5 gals. of water, but manufacturer’s instructions should be consulted wherever possible. It is poisonous to warm-blooded animals, including man, and to fish. Rubber gloves and face shield should be worn when mixing this chemical.

Endosulfan. An insecticide used primarily to control mites, including big-bud mite in blackcurrants. It is also effective against aphids and capsid bugs. It is

available as a liquid to be diluted with water and applied as a spray according to manufacturer’s instructions. It is poisonous to warm-blooded animals, including man, and to fish. Rubber gloves and face shield should be worn when mixing and applying it. Edible crops treated with endosulfan must not be used for at least six weeks. It can only be used on blackcurrants at first open blossom and then three weeks later, and on strawberries after the crop has been picked and before the next season’s flowers open.

Formalin (Formaldehyde). A powerful soil sterilizer. Formalin is the preparation used horticulturally and it contains 38-40% pure formaldehyde. To prepare this for use, all that is necessary is to mix it with 49 times its own bulk of water (1 pt. in 49 pt.; 1 gal. in 49 gals., etc"). Ordinarily, 75 gals. of dilute formalin is sufficient to treat 1 ton of soil, or approximately 2 gals. per bushel of soil. Where possible remove the soil to a hard floor, spread it out thinly and thoroughly saturate with the solution. Throw into a heap and cover with tarpaulins to trap the fumes. After 48 hours, remove the covering and spread the soil out to dry. It must not be used for plants until it ceases to smell of formaldehyde, usually in about three or four weeks.

A 2% solution of formalin is sometimes used as a dip or wash for infected plants, e.g. arum lily tubers affected by bacterial soft rot may be soaked in it for four hours. A 6% solution of formalin may be used to water onion seed drills to prevent onion smut.

Formalin may also be used for sterilizing soil in glasshouses, in frames or in seedboxes and for disinfecting certain seeds, particularly celery, against leaf spot. The seed should be soaked for 3 hours in a solution made by adding 1 part of formalin to 300 parts of water.

Formothion. A systemic insecticide which kills aphids and red spider mites. It is absorbed by the plant and carried round in the sap and can, if desired, be applied from a watering-can to the soil, to be taken up through the roots. This method of application has the advantage that it eliminates all possible danger to bees and useful insects such as ladybirds and lacewing flies. It is poisonous to warm-blooded animals, including man, to bees and to fish but special protective clothing is not required. However, as it belongs to the organo-phosphorus group, special care should be taken if other allied chemicals containing phosphorus have been used because of the possibility of a cumulative effect. Edible crops should not be harvested within a week of the use of formothion. It is available as a liquid to be diluted with water according to manufacturer’s instructions. Chrysanthemums, nasturtiums, African marigolds and possibly some other plants may be damaged, but it is completely safe on roses.

Gishurst Compound, A proprietary insecticide for use against mealy bug on vines. Use in winter when the vines are dormant. Apply direct with a brush to the affected parts.

Lime. This is mainly of value to correct soil acidity for which purpose it can be of great use in the control of club root of cabbages and other brassicas, since this disease thrives in acid soils. It is also used as a slug and snail deterrent. Quicklime is occasionally used to kill soil pests but has been largely replaced for this purpose by more efficient chemicals such as BHC.

Quicklime is very caustic and difficult to handle. It must not come directly in contact with leaves and is best used in winter or on vacant ground. Rate of application is to 1 lb. per square yard well worked in.

Hydrated lime is much easier to handle and is most effective when fresh. It can also be applied at to 1 lb. per square yard either as a top dressing or worked into the soil. As a slug and snail deterrent it is sprinkled around plants and

renewed occasionally, especially following a shower of rain.

Lime Sulphur. One of the most useful fungicides, especially for fruit trees. It is liable to damage the foliage and fruits of pears and certain varieties of apple. It must be purchased as a manufactured liquid. The strength is estimated by specific gravity, the standard being 1.For use on apples and pears mix this as follows:

WINTER APPLICATION: Up to pink bud stage in apples, white bud stage in pears: 11 fl. oz. of lime sulphur to 2 gals. of water.

SUMMER APPLICATION: 3 fl. oz. of lime sulphur to 2 gals. of water.

To control big bug on blackcurrants, lime sulphur is used at twice winter strength, i.e. 22 ft. oz. in 2 gals.

To control cane spot on raspberries, loganberries, and blackberries, lime sulphur is used in winter as for big bud (above) and in summer at double summer strength, i.e. 6 fl. oz. in 2 gals.

Lindane, The name given to the gamma-isomer of BHC at 99 % purity..

Malathion. An insecticide effective agaittst many pests including aphids, leaf hoppers, thrips, suckers, scale insects, mealy bugs, leaf miners, white flies, mushroom flies, gooseberry sawfly, raspberry beetle, pollen beetles and red spider mites. It is poisonous to warm-blooded animals, including man, also to bees and fish but protective clothing is not necessary when it is used. As it belongs to the organo-phosphorus group special care should be exercised if other chemicals of this group are being used because of the danger of cumulative effect. Four days should elapse between use of malathion and harvesting of edible crops.

Malathion is available as an aerosol and a dust, both for immediate use and as a liquid for dilution with water and application as a spray according to manufacturer’s instruc tions. It should not be used on antirrhinums, crassulas, ferns, fuchsias, gerberas, petunias, pileas, sweet peas or zinnias.

Maneb. A synthetic fungicide of the dithiocarbamate group, containing manganese, which is particularly good for the control of downy mildews, rose black spot, potato blight, tomato leaf mould and tomato stem rot (didymella). It is practically non-poisonous, but should not be inhaled and should be kept off the skin. At least one week should elapse between its use on outdoor edible crops and harvesting and two days between use and harvesting of edible greenhouse crops. It is available as a wettable powder to be stirred into water at the rates directed by the manufacturers and agitated while being applied as a spray.

Menazon. A systemic insecticide for use against aphids of all kinds including woolly aphid. It is poisonous to warm-blooded animals, including man, and to bees but no special clothing need be worn when mixing or applying it. Edible crops sprayed with menazon should not be harvested under three weeks. Extra care in handling should be observed if other chemicals of the organo-phosphorus group, to which menazon belongs, are being used because of the danger of accumulation in the body. Menazon is available as a liquid, for dilution with water and application as a spray, as a wettable powder which must be kept agitated after stirring into water and as a dry seed dressing. Manufacturer’s instructions regarding use must be followed.

Mercuric Fungicide. Various organic compounds of mercury are offered under trade names as fungicides, particularly for the control of apple and pear scab or as a lawn disease eradicant. Unlike most other fungicides they are not simply preventive in action but have some effect in killing the fungus even after it has invaded the plant. Mercuric seed dressings are also available. All are

poisonous to warm-blooded animals, including man, and to bees and fish. Edible crops sprayed with mercuric fungicide should not be harvested for at least six weeks. Treated seed must not be fed to humans or animals. The concentrated fungicide should be kept off the skin.

Mercuric fungicides are available as liquids for dilution with water and application as a spray or as dry dressings ready for immediate use. Manufacturer’s instructions must be followed.

Metaldehyde (Meta). Used as a poison bait for slugs and snails at the rate of 1 oz. of finely powdered metaldehyde to 3 lb. of bran. Mix well with sufficient water to make a crumbly mash. Place in small heaps beneath slates or boards. Metaldehyde in specially prepared forms is also available both as pellets for immediate use and in liquid form for mixing with water and application from a watering-can fitted with a rose.

Metham-sodium. Used as a soil sterilizer to kill eelworms and some soil-borne fungi. It is highly damaging to plants so can only be used on vacant land on which nothing will be sown or planted for at least ten weeks. It is a fluid to be diluted with water according to manufacturer’s instructions and applied from a watering-can until the soil is thoroughly wetted. The soil should then be covered with sacks or tarpaulins for a few days, after which the soil should be uncovered so that fumes may escape.

Methiocarb. A chemical used to kill slugs and snails and said to be more efficient than metaldehyde under damp conditions. It is available, ready for use, as small pellets or tablets to be sprinkled around plants liable to be attacked, or wherever slugs or snails are likely to be. It is harmful to fish, and poultry should be kept off treated ground for at least seven days.

Mowrah Meal. This is obtained from the bean of a tropical tree and is used for destroying worms on lawns. The lawn should be dressed at the rate of 4 to 8 oz. per square yard and then watered copiously. The most effective times for treatment are from February to May and August to October, in damp, mild weather when worms are close to the surface. The worms come out and must then be swept up.

Naphthalene, Flaked or powdered naphthalene can be used as a soil insecticide to kill or drive out wireworms, millepedes, cutworms etc. as well as the maggots of the carrot fly, cabbage root fly and onion fly. The naphthalene is scattered over the surface at 2-6 oz. per square yard and forked in or, for fly maggots, is dusted along the rows of young plants in May and June.

Marble-like balls of naphthalene, usually sold as ‘moth balls’, are also a useful deterrent against moles which do not like the smell emitted by the balls. For this purpose they should be dropped into dibber holes 3 or 4 in. deep and 2 or 3 in. apart all round the area to be protected. They normally retain their effectiveness for seveial years.

Nicotine, An insecticide for use against sucking insects such as aphids, capsid bugs, apple sucker, apple sawfly, thrips, leaf hoppers and leaf miners. Nicotine is very poisonous to warm-blooded animals, including man, also to bees and fish, but it is volatile and so soon disappears from plants. Rubber gloves and face shield should be used when diluting the chemical for use but edible crops outdoors treated with nicotine spray can be harvested in two days and glasshouse crops treated with nicotine smoke can be harvested in one day.

Nicotine is available as a dust for immediate use, as a liquid for dilution with water and application as a spray according to manufacturer’s instructions, or in smoke generators for fumigating greenhouses.

For use against apple sucker, nicotine must be applied immediately before the blossom opens, and for apple sawfly 7 to 14 days after it falls. Against other pests, use as soon as noted.

Paradichlorbenzene. Used as a soil fumigant for killing wireworms, millepedes, cutworms, leather-jackets, slugs, etc. The crystals should be broken up as finely as possible and be dropped into 8-in. deep dibber holes made every 9 to 12 in. Refill with soil at once to trap the fumes. A level teaspoonful of powdered crystals will be sufficient for six holes on vacant ground or twelve holes if crops are in growth.

Parathion. An organo-phosphorus insecticide which is very effective against a number of insects including aphids, thrips, scale insects, mealy bugs, leaf miners, white flies and red spider mites. As a soil drench it can also be used to kill cucumber root maggot, millepedes, root knot eelworm, spring-tails, symphalids and woodlice. It is a liquid which may be applied as a spray outdoors or under glass, but as it is very poisonous to human beings and warm-blooded animals generally and also to bees and fish, it must be used with care. It is essential that rubber clothing and a gas mask should be worn when using this insecticide. Special care must be exercised if other chemicals of the organo-phosphorus group, to which parathion belongs, are being used as these tend to accumulate in the body. Edible crops should not be harvested under four weeks after application of parathion. It can be mixed with lime sulphur, Bordeaux mixture, and other alkaline solutions.

Paris Green. An arsenical poison sometimes used in the preparation of poison baits for use against woodlice, leather-jackets, soil caterpillars, slugs, etc. There are two formulae:

1 lb. of Paris Green.

7 lb. of bran. 2 oz. of Paris Green.

7 lb. of dried blood.

In both formulae the two ingredients are mixed thoroughly and placed in small heaps where the pests can get at them, but out of reach of domestic animals, e.g. beneath boards or flat stones, etc. Mixture 1 may be moistened with water to make a crumbly mash which is particularly attractive to leather-jackets and soil caterpillars. Mixture 2 is specially recommended for woodlice. Paris Green is exceedingly poisonous to all warm-blooded animals, including man.

Pepper Dust, This may be sprinkled freely on the leaves and flowers of plants. It is chiefly useful to keep earwigs at bay, but is also of some service against slugs and cats.

Permanganate of Potash. This is sometimes used to kill or deter slugs and snails, for which purpose simply scatter a thin trail of crystals round the plants to be protected or where the pests are known to frequent. It is also employed as a mild fungicide to check damping-off disease of seedlings and to kill moss on lawns. For both purposes 1 oz. of permanganate of potash is dissolved in 1 gal. of water and applied from a watering-can fitted with a fine rose.

Petroleum Oil (White Oil). Proprietary insecticides manufactured from high-grade petroleum oils. Two grades are obtainable, one for winter, the other for summer application. In winter it is used chiefly to control capsid bug eggs and red spider mite winter eggs on fruit trees; in summer to control red spider mites, thrips, scale insects, and white fly on all plants. Summer petroleum is used on a wide variety of plants, particularly glasshouse plants, but may damage carnations, smilax and asparagus fern. Manufacturer’s instructions regarding preparation and application must be followed.

Phosphorus Paste. This is sometimes used as a rat or mouse poison for which purpose it is spread on pieces of bread, cheese, fat, fish or any other attractive bait and placed where the rodents are likely to feed. Phosphorus paste is highly poisonous to all warm-blooded animals, including man, and must be kept out of reach of domestic animals.

Pyrethrum. An insecticide prepared from the flower heads of certain tropical plants. It is not very poisonous to warm-blooded animals, including man, but acts very rapidly on many insects, including aphids, capsid bugs, leaf hoppers and thrips, giving a knock-down effect but not always a complete kill, for which reason it is often combined with slower but more certain insecticides. Pyrethrum is available as a dust ready for use or as a liquid to be diluted with water and applied as a spray according to manufacturer’s instructions.

Quassia. An old-fashioned, non-poisonous insecticide, chiefly used against aphids but now practically superseded by more efficient insect killers. It is intensely bitter and is sometimes used to make plants distasteful to birds.

Quassia extract can be purchased ready for dilution with water and application as a spray according to manufacturer’s instructions. Alternatively it can be prepared by boiling

4 oz. of quassia chips for two hours in a gallon of water. After ten minutes’ boiling, add 1 teaspoonful of carbonate of soda. Dissolve 8 oz. of soft soap in another gallon of water and add the quassia extract. The chips should be strained off and boiled again in a further gallon of water for an hour without carbonate of soda. Finally, add this liquor to that previously obtained, stir well, and make up to

5 gals. with cold water. Apply in the form of a heavy spray.

Quintozene, A fungicide primarily used for the control of soil-borne diseases such as damping off, wire stem, foot rot, root rot and grey bulb rot, and also of tulip fire and lawn diseases such as dollar spot, corticium (red thread) and fusarium patch (snow mould). It is supplied as a dust ready for use and may be worked into the soil, dusted on plants or over bulbs according to manufacturer’s instructions. It is also available as a wettable powder to be stirred into water and kept agitated while being sprayed, watered on or used as a dip. It should not be used on soil intended for cucumbers, marrows or melons.

Red Lead, Ordinary red lead as sold for the preparation of paint can be used as a dressing for seeds to protect them from wireworms, mice and birds. Shake the seeds in a very little paraffin to damp them, then roll them in red lead.

Schradan, A systemic insecticide used mainly against aphids and red spider mites, though it is also effective against most sap suckers. It is very poisonous to all warm-blooded animals, including man, and also to fish. Rubber gloves and face shield should be worn when mixing and applying it. Special care should be taken if other chemicals of the organo-phosphorus group, to which schradan belongs, are being used because of the danger of accumulations in the body. The minimum harvesting time for edible crops sprayed with schradan is four weeks from April to July and six weeks from August to mid-September, after which no sprayed crops should be used. Supplied as a liquid to be diluted with water and applied as a spray according to manufacturer’s instructions.

Soft Soap, Mainly used as a spreader but has some insecticidal properties and is occasionally used to control aphids and red spider mites. For this purpose, use at 5 to 10 oz. to every 5 gals. of water.

Soot, In addition to its use as a fertilizer, soot is also employed as an insecticide. Fresh soot dug into vacant ground at 8 oz. per square yard has some effect in clearing it of slugs, cutworms, wireworms etc., but is rendered more efficient if fresh hydrated lime is applied at the same time. Weathered soot can be dusted on the leaves of celery, chrysanthemums, etc., to ward off leaf-mining flies. It is best applied when the foliage is damp with dew.

Sulphate of Iron. Used to control some soil-borne diseases, notably fairy rings on lawns. The method is to spike the affected area fairly closely to a depth of 4 in., and then to apply a solution of sulphate of iron, mixed with water at the rate of 4 oz. per gallon. The solution is applied freely and can be repeated in six weeks’ time if necessary.

Sulphur. A fungicide particularly useful against mildews and moulds, and also as a deterrent of red spider mites. It is available as a fine powder, often known as ‘flowers of sulphur’, for use direct or in various colloidal or wettable formulations to be mixed with water and applied as a spray according to manufacturer’s instructions. Flowers of sulphur for garden use is often coloured green so that it does not look unsightly on foliage.

Tar-oil Wash. Proprietary sprays made from tar distillate and used to clear fruit trees of caterpillar and aphid eggs, scale insects, lichen, moss, etc. Can only be applied with safety while trees are completely dormant. Usually applied in late December or early January. Manufacturer’s instructions should be obtained where possible. Standard strength is usually 21 pts. to 5 gals. of water, but different brands may vary slightly. Also obtainable as an emulsion for use in the same way. This has the advantage that it mixes with water better and so gives a more complete and econom ical covering of the branches. As tar-oil scorches foliage, care must be taken when applying it to trees underplanted with green crops.

Tecnazene. (TCNB), A fungicide used to control dry rot in potatoes, to check the premature sprouting of stored potatoes and to control grey mould (botrytis) on chrysanthemums, lettuces, tomatoes and other plants grown under glass. It is applied to potatoes as a dust, purchased ready for use at the rate of lb. per 1 cwt. The potatoes must he covered immediately with soil straw or

control grey mould (botrytis) tecnazene is obtained in a smoke generator to be ignited in the greenhouse according to manufacturer’s instructions.

Tetrachlorethane (White Fly Vapour). Used as a fumigant in glasshouses against white fly. It is sold under various trade names and is a colourless fluid. Dose is from 3 to 5 fl. oz. per 1,000 Cu. ft. of house. The specified quantity is sprinkled on the floor towards evening and the house is shut for ,twelve hours. The fumes are poisonous to human beings and domestic animals, and are damaging to Asparagus sprengeri, azaleas, balsam, begonias, chrysanthemums, cinerarias, calceolarias, camellias, cannas, crassulas, dahlias, fuchsias, hydrangeas, lemon verbena (lippia), pelargoniums, salvias, and sweet peas. These should be removed while fumigating. A second fumigation should be given 14 days later, or three applications at intervals of seven days if an attack is very severe. Temperature of house during fumigation should be 70° or higher and the air should be rather dry.

Thiocyanate Winter Wash, Contains petroleum oil and beta-thiocyanodiethyl ether for application to fruit trees to control capsid bugs, red spider mites, woolly aphid and other aphids, caterpillars, apple sucker, etc. It is a fluid which must be diluted with water. Usual strength is 1½ to 2i pts. to 5 gals. of water, but manufacturer’s instructions should be obtained where possible. It should be applied when buds start to expand and each has a green tip (usually March). This wash may prove very useful when bad weather makes it impossible to complete the application of tar oil while the trees are still dormant.

Thiram. A fungicide effective in controlling a wide range of diseases including rose black spot, grey mould (botrytis), tulip fire, some rusts, apple and pear scab, downy mildew, raspberry cane spot and tomato leaf mould, as

well as some soil-borne diseases such as damping off and pea and bean foot rot. It is available as a dust for treatment of seeds before they are sown and also as colloidal or wettable powders to be stirred into water and kept agitated while being applied as a spray. Manufacturer’s instructions must be followed. Thiram should not be used on fruit intended for canning or deep freezing because of a tendency to taint and also to affect the lacquer used inside tins.

Trichlorphon. A synthetic insecticide of the organophosphorus group which is not highly poisonous to warm-blooded animals, including human beings, but is very effective in killing flies and fly larvae, leaf miners, caterpillars, cutworms, earwigs and ants. A minimum period of two days should be allowed between use and harvesting of edible crops. It is applied as a spray. Trichlorphon is harmful to fish.

Washing Soda. Sometimes used as a fungicide primarily for the control of gooseberry mildew, especially on varieties such as Careless, Early Sulphur, Golden Drop and Leveller that are liable to be injured by fungicides containing sulphur. 12 oz. of washing soda and 12 oz. of soft soap are dissolved in 5 gals. of water and applied as a spray every 10 to 14 days from the time the blossom falls until well into the sumnier.

Zineb. A dithiocarbamate fungicide containing zinc which is effective in giving protection against many plant diseases, including potato blight, tomato leaf mould, various mildews and rusts, blackcurrant and celery leaf spot, grey mould (botrytis) and tulip fire. It is virtually non-poisonous but should not be inhaled, should be kept off the skin and it is recommended that outdoor edible crops should not be harvested under one week after application of zineb, glasshouse crops not under two days. It is available as a dust for direct application, or as a wettable powder to be stirred into water, as directed by the makers, and kept agitated while being applied as a spray.

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