Fungicides Bordeaux mixture

Because of its poisonous nature, copper sulfate is used in the fungicide Bordeaux mixture, which is formed upon mixing copper sulfate solution with milk of lime and is added to water reservoirs to kill algae. It is also employed in electroplating and used as a mordant, germicide, and agent in engraving. 

Early in the history of plant chemotherapy the differential toxicity of the therapeutic chemical was related to the limitation of its aqueous solubility. A case in point was the 19th century discovery of the grape fungicide, Bordeaux mixture. 

Bordeaux mixture A mixture of CUSO4 and Ca(OH)2 made up in water and used as a fungicide. 

Copper compounds are used in agriculture to treat mildew and other plant diseases in the food industry as preservatives, additives, or coloring agents in preservatives of wood, leather, and fabrics in coin manufacture and in water treatment (ATSDR1990 Roncero et al. 1992). The use of copper-containing pesticides is traditional along the Mediterranean Coast, especially the use of Bordeaux mixture, a copper sulfate-based fungicide that has been widely used for more than a century to... 

The copper compounds include Bordeaux mixture and the so-called fixed coppers including the copper oxides, copper oxychloride, copper oxychloride sulfate, and related materials. Bordeaux mixture, since its discovery about 70 years ago, has been the classic fungicide for the control of late blight and still is more widely used than any other single material. Certain of its qualities, particularly adhesiveness, remain unequaled by its commercial competitors, and it is cheap and effective. However, the inconvenience of preparing Bordeaux mixture, and the unreliable quality of hydrated lime available in most places, have tempted many growers to switch to other copper compounds or organics. 

Phytophthora Rot (Black Pod). Phytophthora rot is prevalent in most of the world s cacao-growing areas and causes losses comparable to those from swollen shoot. Since 1910 (U2) Bordeaux mixture has been used extensively for the control of this disease in several countries of the Western Hemisphere as well as in Africa. Yield increases due to this chemical control of the disease have been put at 200 to 300% in Costa Rica by Fowler (16). Results (UU) from a fungicidal experiment conducted by the Inter-American Cacao Center in Costa Rica showed an increase in production of approximately 50% when Bordeaux mixture was used. 

This fungicide has been used in Brazil, Ecuador, Puerto Rico, Fernando Po, the West Indies, Philippine Islands, Central American countries, Cameroons, and Nigeria. From Brazil it was recently reported (27) that Bordeaux mixture had only a slight advantage over other compounds. Good results were, however, obtained with Cupro-san in combination with prophylactic measures. From studies conducted in Trinidad, Baker (3) concludes that control of black pod by sanitation and cultural methods is unlikely to be successful, whereas control might be practicable and profitable with spray and modern methods. 

Up to 1952, over 30 fungicides had been tested by this method at La Lola farm of the cacao center (U3). Bordeaux mixture properly prepared was found to be resistant to tropical weathering and the most effective. In some experiments Phy-gon-XL fungicidal powder, Bioquin I, Crag 531, and others were as effective as... 

Bordeaux mixture for the first week. After 4 weeks the effectiveness of Bordeaux mixture decreased somewhat, but for practical purposes the other compounds had almost completely lost the ability to protect plants against the disease. It appears then that there are fungicides as effective as Bordeaux mixture, but none have the residual capacity of this mixture. Perenox (copper oxide), zinc coposil, and cupro-cide (cuprocisoxide), with and without stickers, have also been evaluated. Perenox alone at the concentration of 2 pounds per 100 gallons of water proved to be as effective as 1% Bordeaux mixture. The other two were ineffective. 

Several field experiments were conducted in Costa Rica from 1949 to 1952 by McLaughlin and Bowman (24), in which comparisons were made of Bordeaux mixture at 30- and 60-day intervals and Dithane Z-78 (zinc salt of ethylenebisdithiocar-bamic acid) and SR-406 [captan, n-(trichloromethylthio)-4-cyclohexene-l,2-dicarbox-imide] at 30-day intervals. Bordeaux mixture was found the most effective in reducing infection, but no significant differences were found in yield due to the treatments. Results of 1952 to 1953 experiments (37, 44) showed that Bordeaux mixture and Dithane Z-78 applied every 30 days increased yield in comparison with the other treatments. The yield increase obtained with Dithane might have been due to the presence of zinc in this fungicide and not to a reduction in the incidence of the disease. 

For the control of this disease Bordeaux mixture in combination with better cultural practices has been recommended. Garces (17) recommended similar treatment, but when the pods are still young. Although only preliminary trials have been made on the chemical control of Monilia pod rot in Colombia, initial reports indicated that substantial control was being obtained with fungicidal sprays, but when the results were analyzed statistically they were not significant (18). 

Most fungicides, especially the organic ones, have residual capacity markedly inferior to that of Bordeaux mixture. However, the tenacity could be improved by the addition of adhesives, especially when used in regions of heavy rain. Only preliminary trials in Costa Rica have been conducted in this important problem. Of 14 stickers tested on cacao seedlings in relation to the control of Phytophthora rot of cacao, none gave satisfactory results. 

The second invasion came in 1865 when attempts to control the root aphid Phylloxera through the importation and use of Phylloxera-resistant root stocks inadvertently introduced vine downy mildew, Plasmopara viticola, into the French vineyards. This stimulated what is regarded as the major breakthrough in fungicide use when Millardet, in 1885, acting upon a chance observation, developed the use of Bordeaux mixture, a cocktail of copper sulfate and lime, which is still used extensively in vines and many other crops. 

In 1776 when the Nation was born, we had two useful fungicides for food crops, elemental sulfur and copper sulfate. During the century before the founding of ACS, we added only one more, lime-sulfur in 1803 and this was only a variant of elemental sulfur. Six years after ACS was founded, Bordeaux mixture was born of one of those accidents that Pasteur said happens to the prepared mind. 

Copper sulfate causes ulceration of the oral and esophageal mucosa, and an acute dose of 7-8 g is usually fatal. Copper intoxication has occurred when copper salts were used to treat extensive skin bums or when copper-containing tubing or dialysis membranes were used for hemodialysis. Pulmonary fibrosis has been described in vineyard workers exposed for many years to fungicidal sprays (e.g., Bordeaux mixture ) containing copper sulfate. About 33-50 mg of copper per year ( 100 /rg/d) dissolves from copper-containing intrauterine contraceptive devices. Part of this copper is lost in menstrual flow, but part is rapidly absorbed. Whether this is harmful is not known but it seems unlikely. Penicillamine is the drug of choice for treatment of copper excess. 

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