Copper group of fungicides in Agriculture

The history, development and management of plant diseases through copper group of fungicides.

1. Copper group of fungicides Mohan Raj V 2019045030

2. Copper group of fungicides Copper fungicides are a combination of many different compounds having copper as the common ingredient. These compounds have protectant activity against several bacterial and fungal diseases. These are one of the oldest class of fungicides. The Fungicide Resistance Action Committee sorted the copper fungicides into FRAC M1 .

3. Introduction The oldest copper group of fungicide is the Bordeaux mixture . It was discovered accidently by PMA Millardet in 1882 . Downy Mildew was first noticed in France when Phylloxera vastatrix (Aphid) resistant grapevine rootstocks were imported from US.

4. Phylloxera vastatrix affected grape leaf

5. DOWNY MILDEW INFECTED GRAPES LEAF

6. Then he found that the grapevines along the roadsides had no infestation of powdery mildew. The vines along roadsides were sprayed with a mixture of lime (Calcium hydroxide) and blue vitriol (Copper sulphate) . It was sprayed to avoid the grapes from being plucked along the roads. The spray was visible and the sprayed grapes tasted bitter. The mixture was named as Bordeaux mixture and it was announced as an effective fungicide against downy mildew in the year 1885 .

7. Copper group of fungicides Bordeaux mixture Bordeaux paste Burgundy mixture Cheshunt compound Chaubattia paste Cuprous oxide Copper oxychloride

8. Bordeaux mixture It was discovered by PMA Millardet in 1882 . It generally as a control measure for foliar diseases (Conc. Of 1%) like Grapevine downy mildew caused by Plasmopara viticola Potato late blight caused by Phytophthora infestans Anthracnose Leaf spots Leaf blight Citrus canker caused by Xanthomonas citri p.v. citri

9. It is also used as a soil drenching chemical against nursery diseases like Damping off caused by Pythium sps. & Phytophthora sps. Wilt caused by Rhizoctonia sps. It is used especially at 0.5% conc. for the control of coffee rust caused by Hemileia vastatrix

10. Preparation CHEMICALS REQUIRED Lime – Copper sulphate [CuSO 4 ] - 1kg Blue Vitriol – Calcium hydroxide [Ca(OH) 2 ] - 1kg Water - Hydrogen monoxide [H 2 O] - 100 l These are taken in the ratio of 1:1:100

11. Preparation procedure 1 kg each of CuSO 4 & Ca(OH) 2 are powdered and dissolved separately in 50 l of water each in non-metallic vessels (Earthen / cement / porcelain / plastic vessel ). Lime solution is stained to remove stones & other undissolved materials. CuSO 4 solution is neutralized using addition of Ca(OH) 2 solution with constant stirring . The resulting Bordeaux mixture should be neutral and sky blue in color. Hence Bordeaux mixture is tested for acidity before spraying. If sprayed with free Cu 2+ ions (Acid), it induces phytotoxic effect on plants.

12. Methods for neutrality testing Field test : Polished iron knife/sickle is immersed in Bordeaux mixture for few minutes. If reddish deposits are found on the polished surface, the mixture is acidic in nature. Then the mixture is neutralized using Calcium hydroxide solution and tested again for neutrality.

13. Lab tes t: Litmus paper test – The blue litmus paper is dipped in the Bordeaux mixture. If there is no color change, then the mixture is neutral. pH paper test – Dip the pH paper in the mixture and check for neutrality. Chemical test – Add 5 ml of 10% potassium ferrocyanide to a test tube with Bordeaux mixture. If red precipitate is observed, the mixture is acidic.

14. Chemical action CuSo 4 + Ca(OH) 2 → Cu(OH) 2 + CaSo 4 Cupric hydroxide is toxic to fungi

15. Merits It can be prepared with locally available materials. It is an effective fungicide and highly adhesive. It is relatively cheaper fungicide. It has got good tenacity. It is non-poisonous and safe to handle. It is not phytotoxic to many plants. It controls both foliar diseases and soil borne diseases. As it contains copper, it cures copper deficiency in plants. It has phytotonic effect and prevents defoliation.

16. Demerits The process or preparation is laborious. It has low keeping quality. It is phytotoxic to apple, plums, peaches, pear, rose, sorghum, rice varieties like IR-8 and maize variety like Ganga hybrid, Makka No.3. It leaves blemishes on the leaves after its spray which is unsightly in appearance in ornamental plants. It is corrosive to iron and zinc. Since the coating of Bordeaux mixture on the leaf persists for sometimes temporary retardation of photosynthesis has been reported.

17. Bordeaux paste It is used as wound dresser and protect cut ends of fungal infected trees. It is used as fungicide against Stem bleeding of coconut caused by Ceratocystis paradoxa. Die-back and gummosis of citrus caused by Colletotrichum gloeosporoides . Dendrophthoe affected mango and citrus trees.

18. Stem bleeding of coconut caused by Ceratocystis paradoxa

19. Die-back and gummosis of citrus caused by Colletotrichum gloeosporoides

20. Preparation CHEMICALS REQUIRED Lime – Copper sulphate [CuSO4] - 1kg Blue Vitriol – Calcium hydroxide [Ca(OH)2] - 1kg Water - Hydrogen monoxide [H2O] - 10 l These are taken in the ratio of 1:1:10

21. Burgundy mixture It was developed by Mason in 1887 . It is prepared by mixing copper sulphate crystals and sodium carbonate crystals in water in the ratio of 1.8 kg: 1.8 kg: 100 l .

22. Cheshunt compound It was formulated by Bewley in 1921 . It is used as soil drench against damping off disease caused by Phythium aphanidermatum . It is prepared by mixing powdered copper sulphate and powdered ammonium carbonate in the ratio of 2:11. The dry mixture in stored in air-tight container or else ammonia loss occurs and becomes effective. For spraying, 30 g of dry mixture is dissolved in hot water and made up to 9l using cold water.

23. Chaubattia paste It was developed as wound dressing by Govt. Fruit Research Station at Chaubattia, UP. It is effective against stem brown, stem black, stem canker, pink diseases of apple & pear and collar rot of apple, apricot peaches and plum. It used in Kumaon hills in UP as it is not easily washed away by rain. It is a mixture of 800g of copper carbonate and 800g of red lead in 1l of raw linseed oil or lanolin.

24. Apple Stem Canker

25. Plum Collar Rot

26. Cuprous oxide It’s use was suggested by Horsfall in 1956 . The dust form contains 4 to 6% metallic copper and used at a rate of 25 to 35kg per ha. Wettable powder contains 50% copper and used at 0.25% conc.

27. Copper oxychloride It is less toxic and less effective then Bordeaux mixture. Dust contains 4 to 12% metallic copper and Wettable powders contains 50% copper.

28. Action The copper and its compounds kill the spores of fungi by disrupting certain proteins and enzymes.

29. phytotoxicity Bordeaux mixture causes russeting in apple. Copper oxychloride have phytotoxic effects on IR8 (Rice) and Ganga Hybrid & Makka No.3 (Maize). 0.2% copper fungicides are toxic to rapeseed and mustard.

30. Apple Russeting Brown layer of suberized cells form in the lower epidermal region as the fruit matures.

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