**4.1.4 Cupric chloride**

Copper(II) chloride is a light brown solid chemical compound with the formula CuCl2 and has the potential of slowly absorbing moisture and forming a blue-green dihydrate., The aqueous solution prepared from copper(II) chloride contains a range of copper(II) complexes depending on concentration, temperature, and the presence of additional chloride ions. Copper(II) chloride occurs as a very rare mineral in nature, tolbachite and the dihydrate eriochalcite, more common however are mixed oxyhydroxide-chlorides, like atacamite Cu2(OH)3Cl. There are few preparations of cupric chloride known, used as fungicide in agriculture as well:


CuCl2 is a yellowish to brown, deliquescent powder soluble in water, alcohol and ammonium chloride, used as a mordant in dyeing and printing textiles. CuCl consists of fine grey-black pearls with size of a few hundred µm and a copper content of 64 %. Copper(II) chloride dihydrate (CuCl2 x 2H2O) is built up of blue-green crystals, soluble in water and has a copper content of approx. 37 %. Anhydrous copper(II) chloride is a brown crystal powder, soluble in water and highly hygroscopic, with a copper content of approx. 47 %.

Synonyms of cupric chloride; copper(II) chloride; dichlorocopper, Kupferdichlorid (German); dicloruro de cobre (Spanish); dichlorure de cuivre (French).

#### **4.1.5 Cuprous chloride**

Copper(I) chloride, known also as lower chloride of copper with the formula CuCl (Mr = 99.03 g mol-1) or Cu2Cl2 (Mr = 198.05 g mol-1), is a white solid substance partially soluble in water, but totally in concentrated hydrochloric acid. In middle of 17th century cuprous chloride was first produced by Robert Boyle from mercury(II) chloride and metal Cu: HgCl2 + 2 Cu → 2 CuCl + Hg. Later Proust J.L. prepared CuCl by heating CuCl2 at red heat in absence of air, causing it to lose half of its combined chlorine, followed by removing residual CuCl2 by rinsing with water, and by the application which was widely used for heating and lighting. During the 19th and early 20th Centuries the acidic solution of CuCl

Copper in Horticulture 273

Bud burst and green tip (Sept.), leaf fall (May) and winter dormancy.

Petal fall and at 3-4 weekly intervals

Bud burst and green tip (Sept), leaf fall (May) and winter dormancy.

Dust seed thoroughly prior to sowing. Bud burst and green tip.

Apply when disease first appears. Repeat at 7 – 14 day intervals, whilst conditions favour infection.

Apply when disease first appears. Repeat at 7 – 14 day intervals, whilst conditions favour infection.

Apply at least three sprays at 7 – 10 day intervals. Further applications would be necessary if conditions

Apply when disease first appears. Repeat at 7-14 day intervals as required. Small scale phytotoxicity tests are recommended as some varieties may be sensitive under

Apply at 10 to 14 day intervals, from the seedling stage until maturity, while conditions allow

Apply at 10 – 14 day intervals in wet weather or if conditions favour

Bud burst to harvest at 14 day intervals. Further applications would be necessary if conditions

until harvest.

favour infection.

favour infection.

certain conditions.

infection.

infection.

**Plant Disease Application** 

blast

Black spot, Fire blight, European canker, Leaf curl, Shot hole (die-back), Bacterial spot, Stonefruit

Verrucosis, Brown rot, Melanose, Black spot, Phytophthora blight

Downy mildew, Leaf

Black spot, Downy mildew, Leaf spots, Fire

Seed rots, Anthracnose, Bacterial brown spot, Rust, Rust blight

Anthracnose, Leaf spots, Early and late blight, Bacterial blight

Anthraconse, Bacterial speck, Bacterial spot, Late blight, Septoria leaf spot

Fungal leaf spots, Downy Mildew

spots, Rust

blight

Walnut Walnut Blight

Red beet Downy Mildew,

Strawberries Leaf Spot,

Rust

Leaf Scorch

Table 4. The plants and diseases where the application of copper oxychloride was effective

Pipfruit, Stonefruit

Citrus, Passionfruit

Grapes, Berryfruits

Roses, Ornamentals

Beans, Peas

Broccoli, Carrots, Cucumber, Lettuce, Zucchini

Tomato

Ornamentals

(flowers and shrubs)

was formerly used for analysis of carbon monoxide content in gases, for example in Hempel's gas apparatus. The moist powder's exposure to air and sunlight, results in a color change to yellow, violet and blue-black. The main use of copper(I) chloride is in phytochemistry as a precursor to the fungicide copper oxychloride (dicopper chloride trihydroxide; Cu2(OH)3Cl) green crystalline solid, largely stable in neutral media, but decomposes by warming in alkaline media, yielding oxides, virtually insoluble in water and organic solvents, soluble in mineral acids yielding the corresponding copper salts. For this purpose aqueous copper(I) chloride is generated by comproportionation and later airoxidized:

> Cu + CuCl2 → 2 CuCl 6 CuCl + 3/2 O2 + 3 H2O → 2 Cu3Cl2(OH)4 + CuCl2

Synonyms of cuprous chloride are copper chloride; copper monochloride; chlorid medny; copper(1+) chloride; cuprous monochloride; dicopper dichloride; Kupferchlorid (German); cloruro de cobre (Spanish); chlorure de cuivre (French).

#### **4.1.6 Copper oxychloride**

Copper oxychloride is a basic copper chloride with the formula CuCl2 x 3Cu(OH)2, a green powder used as a blue colour agent and as a fungicide (form as powder, wettable powders and pastes) that controls a wide range of fungal and bacterial diseases of fruits, vegetables and ornamentals. Usually it is manufactured either by the reaction of hydrochloric acid and copper metal or by the air oxidation of cuprous chloride suspensions. It usually contains approx. 57 % of copper and is not soluble in water, but in various acids. Beside its use as fungicide (Table 4) it is also applied as a compound of herbicides and insecticides.

Synonyms of copper oxychloride are copper chloride mixture with copper oxide, hydrate; dicopper chloride trihydroxide; cupric oxide chloride; copper(II) oxychloride; copper oxychloride; vitigran blue; Dikupferchloridtrihydroxid (German); trihidroxicloruro de dicobre (Spanish); trihydroxychlorure de dicuivre (French); tribasic copper chloride; copper chloroxide; copper(II) chloride hydroxide.

#### **4.1.7 Cupric nitrate**

Copper(II) nitrate is also known as copper nitrate, its chemical formula is Cu(NO3)2 (Mr = 232.60 g mol-1). In anhydrous form it is blue coloured, in crystalline and it is used for formulation of fungicides and herbicides. The production of cupric nitrate follows the processes underneath:


Copper nitrate hydrate (Cu(NO3)2nH2O) appears either as a green powder or blue crystallised, it is soluble in water, used in electroplating copper on iron, as a catalyst and nitrating agent in organic reactions, fungicides and wood preservatives and as a pigment for ceramics. Copper(II) nitrate trihydrate (Cu(NO3)2 x 3H2O) is a frequent crystalline product with a copper content of around 26 %, consisting of rather large blue-green crystals.

was formerly used for analysis of carbon monoxide content in gases, for example in Hempel's gas apparatus. The moist powder's exposure to air and sunlight, results in a color change to yellow, violet and blue-black. The main use of copper(I) chloride is in phytochemistry as a precursor to the fungicide copper oxychloride (dicopper chloride trihydroxide; Cu2(OH)3Cl) green crystalline solid, largely stable in neutral media, but decomposes by warming in alkaline media, yielding oxides, virtually insoluble in water and organic solvents, soluble in mineral acids yielding the corresponding copper salts. For this purpose aqueous copper(I) chloride is generated by comproportionation and later air-

Cu + CuCl2 → 2 CuCl 6 CuCl + 3/2 O2 + 3 H2O → 2 Cu3Cl2(OH)4 + CuCl2 Synonyms of cuprous chloride are copper chloride; copper monochloride; chlorid medny; copper(1+) chloride; cuprous monochloride; dicopper dichloride; Kupferchlorid (German);

Copper oxychloride is a basic copper chloride with the formula CuCl2 x 3Cu(OH)2, a green powder used as a blue colour agent and as a fungicide (form as powder, wettable powders and pastes) that controls a wide range of fungal and bacterial diseases of fruits, vegetables and ornamentals. Usually it is manufactured either by the reaction of hydrochloric acid and copper metal or by the air oxidation of cuprous chloride suspensions. It usually contains approx. 57 % of copper and is not soluble in water, but in various acids. Beside its use as

Synonyms of copper oxychloride are copper chloride mixture with copper oxide, hydrate; dicopper chloride trihydroxide; cupric oxide chloride; copper(II) oxychloride; copper oxychloride; vitigran blue; Dikupferchloridtrihydroxid (German); trihidroxicloruro de dicobre (Spanish); trihydroxychlorure de dicuivre (French); tribasic copper chloride; copper

Copper(II) nitrate is also known as copper nitrate, its chemical formula is Cu(NO3)2 (Mr = 232.60 g mol-1). In anhydrous form it is blue coloured, in crystalline and it is used for formulation of fungicides and herbicides. The production of cupric nitrate follows the

Copper nitrate hydrate (Cu(NO3)2nH2O) appears either as a green powder or blue crystallised, it is soluble in water, used in electroplating copper on iron, as a catalyst and nitrating agent in organic reactions, fungicides and wood preservatives and as a pigment for ceramics. Copper(II) nitrate trihydrate (Cu(NO3)2 x 3H2O) is a frequent crystalline product

b. hydrolysis of the anhydrous material (preparation of copper nitrate hydrate) and c. treating copper metal with an aqueous solution of silver nitrate or concentrated nitric

with a copper content of around 26 %, consisting of rather large blue-green crystals.

fungicide (Table 4) it is also applied as a compound of herbicides and insecticides.

a. treating metal Cu with N2O4 (Cu + 2 N2O4 → Cu(NO3)2 + 2 NO),

acid (Cu + 4 HNO3 → Cu(NO3)2 + 2 H2O + 2 NO2)

cloruro de cobre (Spanish); chlorure de cuivre (French).

oxidized:

**4.1.6 Copper oxychloride** 

**4.1.7 Cupric nitrate** 

processes underneath:

chloroxide; copper(II) chloride hydroxide.


Table 4. The plants and diseases where the application of copper oxychloride was effective

Copper in Horticulture 275

Copper naphthenate in terms of new and environmentally-sound timber preservatives presents an alternative to the use of restricted pesticides. It offers positive benefits with regards to safety, performance, application and the environment; furthermore it is not classified as a "Restricted Use Pesticide", nor does it contain dioxins, carcinogens, chrome arsenic, lindane, pentachlorophenol (PCP) or tributyltin oxide (TBTO). Copper naphthenate products are highly effective against wood-destroying fungi and insects; Cu salt prevents also fungal decay and insect attack, furthermore water resistant features of naphthenate

Copper soap known also as copper octanoate or octanoic acid (as active agent in conc. approx. 0.08 %), copper soap is mostly used to control fungal and bacterial plant diseases (powdery mildew, blackspot, blight, downy mildew, gray mold and many others affecting flowers, fruits and vegetables). Copper soap is produced by combining a soluble Cu fertilizer with a naturally-occurring fatty acid. Copper and the fatty acid together form copper salt of fatty acids, technically known as soap with a copper concentration lower than 90 ppm. The soap has to be applied by spraying all plant surfaces two weeks before infection and occurrence of the disease. In agriculture, it can be mixed with other pesticides as well and applied by ground equipment or aircraft. It should be applied at first signs of disease and repeated every 7-10 days until favourable disease conditions are no longer

Copper is an essential element for the normal healthy growth and reproduction of all higher plants and animals, especially in the context of haemoglobin in the blood, formation of collagen and it is protective coverings for nerves. In combination with other metallic elements, along fatty and amino acids as well as vitamins, Cu is necessary for normal metabolic processes. The human body is unable to produce metals; therefore the human diet

Cu is present in different species and varieties of plants especially in fruits and vegetables, nuts, seeds, chickpeas, liver, oysters and in some water. Satisfactory amounts of copper that provide up to 50 % of the required whole intake in a balanced diet can be found also in other cereals, meat and fish. Copper deficiency can lead to coronary diseases, higher cholesterol levels, premature births, chronic diarrhoea, stomach diseases, nauseas and other adverse effects, that are observed in most developed countries as well. Copper is incorporated in certain proteins, which are involved in the production of energy required in biochemical reactions, while others take part in the transformation of melanin essential for the pigmentation of the skin. Many of these help maintaining and repairing connective tissues indispensable for the proper functions of heart and arteries. Copper has been used as a medicine for thousands of years including the treatment of chest wounds and treating drinking water. More recently, research has indicated that copper helps prevent

The quantity of copper at an adult person ranges from 1.4 to 2.1 mg per kilogramme of body weight. The average daily uptake of copper should be from 0.4 mg for children up to 1.2 mg

prevent rot and elongate life expectancy of timber.

**5. Copper and human health: Fruit and vegetable** 

must supply regular amounts of bioavailable Cu.

inflammation in arthritis and similar diseases.

**4.1.10 Copper soap** 

present.

Synonyms of cupric nitrare are cupric nitrate hemipentahydrate; nitric acid, copper (II) salt, hydrate (2:5); copper II nitrate hemihydrate; Kupferdinitrat (German); dinitrato de cobre (Spanish); dinitrate de cuivre (French).

#### **4.1.8 Copper cyanide**

Copper(I) cyanide as an inorganic compound and has the chemical formula CuCN, due to the presence of Cu(II) impurities it can be green, it is a useful in electroplating copper, furthermore it can also be applied as a reagent in the preparation of nitriles. It is insoluble in water but rapidly dissolves in solutions containing CN- to form [Cu(CN)3]2 and [Cu(CN)4]3-. CuCN, a white crystalline poisonous powder, is produced by the reaction of cuprous chloride and sodium cyanide and used mainly in electroplating, due to its ability to form complex cyanides. It contains approx. 71 % of copper and is produced as follows:


It is used as a fumigant in agriculture. The principal use of hydrogen cyanide is in the manufacture process of acrylates, synthetic fibres, plastics and cyanide salts and pesticides. Cyanide salts are utilized in metal cleaning, gardening, invarious organic reactions in manufacture production. It is also used for the production of monomers (e.g. acrylates) as well as an ingredient of fumigants and pesticides. Copper compounds form a protective barrier on the plant surface and thereby prevent fungi from entering the plant host. The copper compounds as non-systemic fungicides operate as Bordeaux mixture, cupric hydroxide, copper arsenate, copper carbonate, cuprous oxide, copper oxychloride etc.

Synonyms of copper cyanide are cianuro de cobre (Spain); Kupfercyanid (Germany); cyanure de cuivre (France).

#### **4.1.9 Copper naphthenate**

Copper naphthenate is a copper salt of naphthenic acid, which is a complex natural mixture of fatty acids, by-product of petroleum refining and it takes part in variable compositions (contaminants, inert, and by-products). Naphthenates are mainly applied for industrial use, including the oriduction of synthetic detergents, lubricants, corrosion inhibitors, fuel and lubricating oil additives, wood preservations, insecticides, fungicides, acaricides, wetting agents as well as oil drying agents used in painting and wood surface treatment. A typical copper naphthenate product appears as a green liquid with about 19% copper naphthenate and 81% unlisted ingredients. The cyclopentylacetic acid, alkyl-substituted cyclopentylacetic acids, fused chains of cyclopentylacetic acids, cyclohexylacetic acids, cyclopentanoic acids, and various low-molecular-weight fatty acids all represent frequent constituents of naphthenic acids.

Synonyms of cupric nitrare are cupric nitrate hemipentahydrate; nitric acid, copper (II) salt, hydrate (2:5); copper II nitrate hemihydrate; Kupferdinitrat (German); dinitrato de cobre

Copper(I) cyanide as an inorganic compound and has the chemical formula CuCN, due to the presence of Cu(II) impurities it can be green, it is a useful in electroplating copper, furthermore it can also be applied as a reagent in the preparation of nitriles. It is insoluble in water but rapidly dissolves in solutions containing CN- to form [Cu(CN)3]2 and [Cu(CN)4]3-. CuCN, a white crystalline poisonous powder, is produced by the reaction of cuprous chloride and sodium cyanide and used mainly in electroplating, due to its ability to form complex cyanides. It contains approx. 71 % of copper and is produced

a. by the reduction of copper(II) sulfate with sodium bisulphite at 60 °C, followed by the addition of sodium cyanide to precipitate pure LT-CuCN as a pale yellow powder (2 CuSO4 + NaHSO3 + H2O + 2 NaCN → 2 CuCN + 3 NaHSO4). By the addition of sodium bisulphite the copper sulphate solution becomes green, at that point sodium cyanide

b. by treating copper(II) sulfate with sodium cynide in a redox reaction, copper(I) cyanide forms together with cyanogen (2 CuSO4 + 4 NaCN → 2 CuCN + (CN)2 + 2 Na2SO4) It is used as a fumigant in agriculture. The principal use of hydrogen cyanide is in the manufacture process of acrylates, synthetic fibres, plastics and cyanide salts and pesticides. Cyanide salts are utilized in metal cleaning, gardening, invarious organic reactions in manufacture production. It is also used for the production of monomers (e.g. acrylates) as well as an ingredient of fumigants and pesticides. Copper compounds form a protective barrier on the plant surface and thereby prevent fungi from entering the plant host. The copper compounds as non-systemic fungicides operate as Bordeaux mixture, cupric hydroxide, copper arsenate, copper carbonate, cuprous oxide, copper oxychloride

Synonyms of copper cyanide are cianuro de cobre (Spain); Kupfercyanid (Germany);

Copper naphthenate is a copper salt of naphthenic acid, which is a complex natural mixture of fatty acids, by-product of petroleum refining and it takes part in variable compositions (contaminants, inert, and by-products). Naphthenates are mainly applied for industrial use, including the oriduction of synthetic detergents, lubricants, corrosion inhibitors, fuel and lubricating oil additives, wood preservations, insecticides, fungicides, acaricides, wetting agents as well as oil drying agents used in painting and wood surface treatment. A typical copper naphthenate product appears as a green liquid with about 19% copper naphthenate and 81% unlisted ingredients. The cyclopentylacetic acid, alkyl-substituted cyclopentylacetic acids, fused chains of cyclopentylacetic acids, cyclohexylacetic acids, cyclopentanoic acids, and various low-molecular-weight fatty acids all represent frequent constituents of

(Spanish); dinitrate de cuivre (French).

**4.1.8 Copper cyanide** 

should be added.

cyanure de cuivre (France).

**4.1.9 Copper naphthenate** 

naphthenic acids.

as follows:

etc.

Copper naphthenate in terms of new and environmentally-sound timber preservatives presents an alternative to the use of restricted pesticides. It offers positive benefits with regards to safety, performance, application and the environment; furthermore it is not classified as a "Restricted Use Pesticide", nor does it contain dioxins, carcinogens, chrome arsenic, lindane, pentachlorophenol (PCP) or tributyltin oxide (TBTO). Copper naphthenate products are highly effective against wood-destroying fungi and insects; Cu salt prevents also fungal decay and insect attack, furthermore water resistant features of naphthenate prevent rot and elongate life expectancy of timber.

#### **4.1.10 Copper soap**

Copper soap known also as copper octanoate or octanoic acid (as active agent in conc. approx. 0.08 %), copper soap is mostly used to control fungal and bacterial plant diseases (powdery mildew, blackspot, blight, downy mildew, gray mold and many others affecting flowers, fruits and vegetables). Copper soap is produced by combining a soluble Cu fertilizer with a naturally-occurring fatty acid. Copper and the fatty acid together form copper salt of fatty acids, technically known as soap with a copper concentration lower than 90 ppm. The soap has to be applied by spraying all plant surfaces two weeks before infection and occurrence of the disease. In agriculture, it can be mixed with other pesticides as well and applied by ground equipment or aircraft. It should be applied at first signs of disease and repeated every 7-10 days until favourable disease conditions are no longer present.
