Copper fungicides work by slowly releasing positively charged copper ions Cu+ and Cu2+ in concentrations that interact with nucleic acids, interfere with energy transport, disrupt enzyme activity, and affect the integrity of cell membranes of pathogens.[5][6] Both ions have fungicidal and bactericidal activity. Following absorption into the fungus or bacterium, the copper ions will link to various chemical groups (imidazole, phosphate, sulfhydryl, and, hydroxyl groups) present in many proteins and disrupt their functions. Copper ions can kill pathogen cells on plant surfaces, but once a pathogen enters host plant tissue, it is no longer susceptible to copper treatments at the prescribed concentrations. The prescribed copper ion concentrations lack post-infection activity. Higher copper ion concentrations harm the host plant.[7]
Application
The use of copper pesticide in viticulture in 1940
Copper pesticide is applied as a contact protective foliar spray, so it remains deposited on leaf surfaces. A small concentration of copper ions may be taken up by plants as essential nutrients. Copper foliar sprays are also applied to correct plant copper deficiency.[8] Excess absorbed copper ions can kill sensitive cells in copper sensitive plants. The leaves of stone fruit trees are more sensitive to copper phytotoxicity than apple leaves. Copper tolerant plant families include Cruciferae, Caryophyllaceae, Gramineae, Leguminosae and Asteraceae.[9]
Copper phytotoxicity worsens under slow drying conditions. Adding surfactants with copper fungicides may increase injury to plant foliage. Copper ions release more readily under acidic conditions and copper pesticides, except copper sulfate pentahydrate, should not be used with acid forming products.[10] Copper fungicides can be highly effective if applied prophylactically and with complete coverage of all plant foliar surfaces, including the undersides of leaves where the pathogen typically sporulates.[11]
Copper pesticides must be used in quantities that minimizes long term copper accumulation in the soil. Accumulated copper in soils can inhibit root growth and adversely affect microorganisms and earthworms. Finely ground copper formulations are more active than coarsely ground formulations. Coarsely ground formulations should be avoided to limit long term bioaccumulation and toxicity.[12] Copper occurs in soils in different forms (ionic, complexed and precipitated) depending on characteristics such as soil texture, organic matter and pH.
Effectiveness
A strategy to maximize the effectiveness of copper ions is to reduce the particle size of the active substance (micronization) and copper microencapsulation. These improve relative coverage of treated plant surfaces or extend copper ion releases. Modern copper application dose rates may be as low as 200-400g per treatment per hectare.
↑ David Ritchie, Copper-containing fungicides/bactericides and their use in management of bacterial spot on peaches, Southeast Regional Newsletter. Vol. 4, No. 1, March 2004
↑ Reregistration Eligibility Decision (RED) for Coppers, USEPA, 2006
↑ Archived 24 October 2021 at the Wayback Machine Anna LA TORRE, Valeria IOVINO and Federica CARADONIA; Copper in plant protection: current situation and prospects; Phytopathologia Mediterranea (2018), 57, 2, 201−236 www.fupress.com/pm ISSN (print): 0031-9465 Firenze University Press ISSN (online): 1593-2095 DOI: 10.14601/Phytopathol_Mediterr-23407
↑ S. E. A. McCallan, The Nature of the Fungicidal Action of Copper and Sulfur, Botanical Review Vol. 15, No. 9 (Nov. 1949), pp. 629-643 (15 pages) Published By: Springer
↑ Pscheidt, Jay W. Copper-based Bactericides and Fungicides, Pacific Northwest Pest Management Handbooks, Oregon State University
↑ How Copper Sprays Work and Avoiding Phytotoxicity, T. A. Zitter, Cornell University Department of Plant Pathology & Plant-Microbiology and David A. Rosenberger, Professor of Plant Pathology, Cornell University's Hudson Valley Lab, 2013
↑ Amlal Fouad, Drissi Saad, Makroum Kacem, Maataoui Abdelwahed, Dhassi Khalid, Rahmani Abderrahim & Aït Houssa Abdelhadi (2020) Efficacy of copper foliar spray in preventing copper deficiency of rainfed wheat (Triticum aestivum L.) grown in a calcareous soil, Journal of Plant Nutrition, 43:11, 1617-1626, DOI: 10.1080/01904167.2020.1739294
↑ Xiong Z.T. and H. Wang, 2005. Copper toxicity and bioaccumulation in Chinese cabbage (Brassica pekinensis Rupr.). Environmental Toxicology 20, 188–194
↑ GARVER ERNEST, EMMALEA; CAUTION WITH COPPER FUNGICIDES AND SPRAY SURFACTANTS IN VEGETABLES AND FRUITS, University of Delaware Extension, 2013
↑ Stone, Alex et al; Organic Management of Late Blight of Potato and Tomato with Copper Products; Oregon State University, Published 18 March 2010
↑ Dave Rosenberger, Options, Benefits, and Liabilities for Copper Sprays in Tree Fruits; Hudson Valley Laboratory, Cornell University; Fruit Notes, Volume 77, Spring, 2012
↑ Archived 24 October 2021 at the Wayback Machine Anna LA TORRE, Valeria IOVINO and Federica CARADONIA; Copper in plant protection: current situation and prospects; Phytopathologia Mediterranea (2018), 57, 2, 201−236 www.fupress.com/pm ISSN (print): 0031-9465 Firenze University Press ISSN (online): 1593-2095 DOI: 10.14601/Phytopathol_Mediterr-23407
↑ A. R. Chase, All Coppers Are Not Created Equal, GrowerTalks Pest Management, 2020
Benedict's reagent is a chemical reagent and complex mixture of sodium carbonate, sodium citrate, and copper(II) sulfate pentahydrate. It is often used in place of Fehling's solution to detect the presence of reducing sugars. The presence of other reducing substances also gives a positive result. Such tests that use this reagent are called the Benedict's tests. A positive test with Benedict's reagent is shown by a color change from clear blue to brick-red with a precipitate.
Citrus production encompasses the production of citrus fruit, which are the highest-value fruit crop in terms of international trade. There are two main markets for citrus fruit:
Copper(II) sulfate is an inorganic compound with the chemical formula CuSO4. It forms hydrates CuSO4·nH2O, where n can range from 1 to 7. The pentahydrate (n = 5), a bright blue crystal, is the most commonly encountered hydrate of copper(II) sulfate, while its anhydrous form is white. Older names for the pentahydrate include blue vitriol, bluestone, vitriol of copper, and Roman vitriol. It exothermically dissolves in water to give the aquo complex [Cu(H2O)6]2+, which has octahedral molecular geometry. The structure of the solid pentahydrate reveals a polymeric structure wherein copper is again octahedral but bound to four water ligands. The Cu(II)(H2O)4 centers are interconnected by sulfate anions to form chains.
Fungicides are pesticides used to kill parasitic fungi or their spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, and profit. Fungicides are used both in agriculture and to fight fungal infections in animals. Fungicides are also used to control oomycetes, which are not taxonomically/genetically fungi, although sharing similar methods of infecting plants. Fungicides can either be contact, translaminar or systemic. Contact fungicides are not taken up into the plant tissue and protect only the plant where the spray is deposited. Translaminar fungicides redistribute the fungicide from the upper, sprayed leaf surface to the lower, unsprayed surface. Systemic fungicides are taken up and redistributed through the xylem vessels. Few fungicides move to all parts of a plant. Some are locally systemic, and some move upward. Most fungicides that can be bought retail are sold in liquid form, the active ingredient being present at 0.08% in weaker concentrates, and as high as 0.5% for more potent fungicides. Fungicides in powdered form are usually around 90% sulfur.
A phosphite anion or phosphite in inorganic chemistry usually refers to [HPO3]2− but includes [H2PO3]− ([HPO2(OH)]−). These anions are the conjugate bases of phosphorous acid (H3PO3). The corresponding salts, e.g. sodium phosphite (Na2HPO3) are reducing in character.
Magnesium chloride is an inorganic compound with the formula MgCl2. It forms hydrates MgCl2·nH2O, where n can range from 1 to 12. These salts are colorless or white solids that are highly soluble in water. These compounds and their solutions, both of which occur in nature, have a variety of practical uses. Anhydrous magnesium chloride is the principal precursor to magnesium metal, which is produced on a large scale. Hydrated magnesium chloride is the form most readily available.
The oligodynamic effect is a biocidal effect of metals, especially heavy metals, that occurs even in low concentrations. This effect is attributed to the antibacterial behavior of metal ions, which are absorbed by bacteria upon contact and damage their cell membranes.
Bordeaux mixture (also called Bordo Mix) is a mixture of copper(II) sulphate (CuSO4) and quicklime (CaO) used as a fungicide. It is used in vineyards, fruit-farms and gardens to prevent infestations of downy mildew, powdery mildew and other fungi. It is sprayed on plants as a preventive treatment; its mode of action is ineffective after a fungus has become established. It was invented in the Bordeaux region of France in the late 19th century. If it is applied in large quantities annually for many years, the copper in the mixture eventually becomes a pollutant. As such its use is controlled, but not forbidden in most of the European Union. Despite this, some advocates of organic gardening consider it an 'organic' pesticide.
Algaecide or algicide is a biocide used for killing and preventing the growth of algae, often defined in a loose sense that, beyond the biological definition, also includes cyanobacteria. An algaecide may be used for controlled bodies of water, but may also be used on land for locations such as turfgrass.
Burgundy mixture, named after the French district where it was first used to treat grapes and vines, is a mixture of copper sulfate and sodium carbonate. This mixture, which can have an overall copper concentration within the range of 1% through 20%, is used as a fungicidal spray for trees and small fruits.
Plasmopara viticola, the causal agent of grapevine downy mildew, is a heterothallic oomycete that overwinters as oospores in leaf litter and soil. In the spring, oospores germinate to produce macrosporangia, which under wet condition release zoospores. Zoospores are splashed by rain into the canopy, where they swim to and infect through stomata. After 7–10 days, yellow lesions appear on foliage. During favorable weather the lesions sporulate and new secondary infections occur.
Acephate is an organophosphate foliar and soil insecticide of moderate persistence with residual systemic activity of about 10–15 days at the recommended use rate. It is used primarily for control of aphids, including resistant species, in vegetables and in horticulture. It also controls leaf miners, caterpillars, sawflies, thrips, and spider mites in the previously stated crops as well as turf, and forestry. By direct application to mounds, it is effective in destroying imported fire ants.
Thiram is the simplest thiuram disulfide and the oxidized dimer of dimethyldithiocarbamate. It is used as a fungicide, ectoparasiticide to prevent fungal diseases in seed and crops and similarly as an animal repellent to protect fruit trees and ornamentals from damage by rabbits, rodents and deer. It is effective against Stem gall of coriander, damping off, smut of millet, neck rot of onion, etc. Thiram has been used in the treatment of human scabies, as a sun screen and as a bactericide applied directly to the skin or incorporated into soap.
This is an index of articles relating to pesticides.
Timorex Gold is a natural botanical broad spectrum fungicide with prophylactic and curative activity, based on a plant extract of Melaleuca alternifolia. Timorex Gold is effective against a wide range of plant-pathogenic fungi, including Oomycetes, Ascomycetes, and Basidiomycota, on numerous crops, including vegetables, herbs, grapevines, fruit trees, and banana. Timorex Gold has demonstrated high efficacy against Black Sigatoka. Plants damaged by Black Sigatoka have a significant reduction in the photosynthesizing area of the leaf, and fruit yield losses can reach 50% through premature maturation.
Spilocaea oleaginea is a deuteromycete fungal plant pathogen, the cause of the disease olive peacock spot, also known as olive leaf spot and bird's eye spot. This plant disease commonly affects the leaves of olive trees worldwide. The disease affects trees throughout the growing season and can cause significant losses in yield. The disease causes blemishes on the fruit, delays ripening, and reduces the yield of oil. Defoliation and in severe cases, twig death, can occur, and the disease can have long-term health effects on the trees.
Trunk injection or endotherapy also known as vegetative endotherapy, is a method of target-precise application of pesticides, plant resistance activators, or fertilizers into the xylem vascular tissue of a tree with the purpose of protecting the tree from pests, or to inject nutrients to correct for nutrient deficiencies. This method largely relies on harnessing the tree's vascular system to translocate and distribute the active compounds into the wood, canopy and roots where protection or nutrition is needed.
Phoma wilt is a disease of the common hop plant caused by several species of fungal plant pathogens in the genus Phoma. These include Phoma herbarum and Phoma exigua, and possibly other as yet unidentified species. Phoma infection may cause decreased yields, but Phoma wilt is not considered to be a very common or destructive disease of the hop plant.
Black rot on orchids is caused by Pythium and Phytophthora species. Black rot targets a variety of orchids but Cattleya orchids are especially susceptible. Pythium ultimum and Phytophthora cactorum are known to cause black rot in orchids.
Copper forms a rich variety of compounds, usually with oxidation states +1 and +2, which are often called cuprous and cupric, respectively. Copper compounds, whether organic complexes or organometallics, promote or catalyse numerous chemical and biological processes.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
