INTERACTION OF SYSTEMIC FUNGICIDES WITH SOIL MICRO ORGANISMS

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1 INTERACTION OF SYSTEMIC FUNGICIDES WITH SOIL MICRO ORGANISMS Charanjit Kaur Department of Chemistry, Sri Sathya Sai College, Bhopal (INDIA) Received May 2, 2006 Accepted June 14, 2006 ABSTRACT Pesticides have added substantially to world s food production but some of them have an adverse effect on crop plants, poison water and soil. Rhizobium in symbiotic association with legume seeds is of paramount importance to agriculture. Pesticides can inhibit Nodulation, nitrogen fixation and growth of various legumes. A comparative study of the effect of Dodine and Actidione (systemic fungicides) was undertaken in the M.P.Agro Bio Fertilizer Plant, Indrapuri Bhopal (India). Dodine was observed to be toxic to nodule bacterium while Actidione was observed to be compatible with Rhizobium japonicum. Key Words : Fungicides, Pathogen, Toxicity, Micro organism, Seed dressing. INTRODUCTION Fungicides in soil may originate from soil treatment, seed dressing or as run off from folier sprays. Early work on effects of fungicides on soil microflora has been reviewed by Kreutzer. During the last ten years the most significant breakthrough in chemical pesticide research has certainly been the introduction of commercially viable systemic fungicides. The development of specific systemic fungicide has been hailed as a significant breakthrough in the fungicide technology. These fungicides are usually applied to plant foliage as dust or sprays. The plants via the roots, leaves or seeds absorb these plant chemotherapeutents. They have a known and restricted mode of action. Following the application, they enter the plant, Tran located and then act directly upon the pathogen by virtue of their fungitoxic properties, thus providing protection as well as eradicating already established infection 1-11 Most systemic fungicides are metabolized within the plant tissues and if the metabolites are inactive, this will result in steady loss of effectivity. Evidences suggest that Dodine fungicides penetrate the host tissues and exhibit local systemic eradicant properties. It was suggested by Miller that the fungi toxic properties of Dodine fungicide is because of its intake by the conidia of a large number of fungi. The present intense agricultural practice calls for the use of a lot of fungicides on crop plants. A considerable portion of these fungicides eventually reaches the soil but the information on the residual effects of many of these 11

2 fungicides on beneficial microorganism such as Rhizobium and Azotobacter is lacking 12. In the light of the above facts, the present study was undertaken. Dodine Chemical name n-dodecyl guanidine acetate Chemical family Organic, systemic Molecular formula C 15 H N O Supplier Bhopal Pesticides, Bhopal Molecular weight Physical form Colourless crystalline solid Melting point 136 C Stability Stable in neutral and acidic media Decomposed by strong alkalies Solubility 63 mg/litre in water. Soluble in hot water and alcohol. Insoluble in most of organic solvents Toxicity Irritating to skin Mode of action Foliar spray Actidione Chemical name Cycloheximide Chemical family Organic, Systemic Molecular formula C 15 H 23 NO 4 Molecular weight Physical form Colourless crystals Melting point 115 ºC Stability Stable to heat, stable in neutral and acidic solutions but rapidly decomposed by alkalies Solubility 21g/litre in water. Readily soluble in chloroform, ether, acetone, alcohol etc. Toxicity Mode of action Irritating to skin. Foliar spray MATERIAL AND METHODS Black cotton soil samples were collected and sterilized in an autoclave for three consecutive days at 121 C for two hours per day. Five days old cultures of Bradyrhizobium japonicum having 10 8 cells/ml were added to soil in the ratio of 10 ml of both culture in 100 gms of soil. Calculated quantities of fungicide solution were added to maintain the concentration of 100, 200, 300, 400 and 500 ppm. The contents were mixed thoroughly and packed in low density polythene bags of 200 gauge sealed by electric sealer and kept for 21, 30, and 45 days at C. After completion of desired incubation period soil samples were withdrawn and used for colony counting with the help of colony counter. RESULTS AND DISCUSSION Rhizobium in symbiotic association with legumes is of paramount importance to agriculture. Results reveal that there is gradual decrease in viable counts of organism (Rhizobium japonicum) as the conc. of fungicide increases from 100 to 500 ppm. It is also observed that Dodine is inhibitorier torhizobium as compared to Actidione. Among the strains CH-1, CH-2, CH-6 and CH-7C were observed to give higher counts suggesting better quality strains than others. The severe inhibition caused by Dodine reflects the drastic decrease in the growth on agar, the action is observed to be bactericidal rather than bacteriostatic. Since Dodine is an alkyl cationic surfactant having a long chain of 14 carbon-atoms, which gets bound to the hydrophobic regions. There is not much difference in the viable counts of organism in the fungicide treated soils and untreated control therefore fungicide treatment can safely be used as a routine. 12

3 Table 1 Viable counts of various isolates of Rhizobium japonicum in contact with Actidione Fungicide Observations after 30 days Control Table 2 Viable counts of various isolates of Rhizobium japonicum in contact with Actidione Fungicide Observations after 45 days Control

4 Table 3 Viable counts of various isolates of Rhizobium japonicum in contact with Dodine Fungicide Observations after 30 days Control Table 4 Viable counts of various isolates of Rhizobium japonicum in contact with Dodine Fungicide Observations after 45 days Control

5 REFERENCES 1. Pesticides Prep., and Mode of action by Cremlin John Wiley & Sons, Chi Chester New York, Chap. 7, Fungicides (1980). 2. Wooed A., Pest controls : A survey. McGraw Hill, London, 93 (1974). 3. Hartley G.S. and West T.F., Chemicals for Pest Control, Pergamon Press, Oxford, pp. 191 (1969). 4. Martini H., The Scientific Principles of Crop Protection, 6th Edn. Arnold London, 122 (1973). 5. Harshall K.A., World Crop Protection. Pesticides. Vol. 2, Iliffe Books Ltd., London, 154 (1969). 6. Nene Y.L. and Thaliyal P.N. Fungicides in Plant Disease Control (1982). 7. Kreutzer W.A., Rev. Phytopath.1, 101 (1963). 8. Daitloff A., Soil Bio. Biochem. 18, 1, (1986). 9. Avid D. Fisher. Effect of some fungicides on Rhizobium. Pest Sci. 7, (1976) 10. Vonk J. W., Kaars Sijesteijn. A Pesticide Science 2, 160 (1971). 11. Graham Bryce I.J., Proc. 7 th Br. Insecticide Fungicide Conf. 3, 921 (1973). 12. Baker Z., Harrison R.W. and Miller F., J. Exp. Med. 73, 249 (1941). DECLARATION BY THE AUTHOR(S) I/We. declare that the manuscript (Full Length Research Paper/Short communication/review paper) entitled submitted to the Journal of Environmental Research And Development, have not been published and have not been submitted for publishing elsewhere, besides manuscript is my/our original work. Moreover I/we assure to put my/our best efforts for the upliftment of environment. Date : Signature of Author(s) Place : Name(s) in Full 15