Management of bacterial blight of cotton induced by Xanthomonas axonopodis pv. malvacearum with the use of neem based formulations

Size: px

Start display at page:

Download "Management of bacterial blight of cotton induced by Xanthomonas axonopodis pv. malvacearum with the use of neem based formulations"

Ella Richards
5 years ago
Views:

Indian Phytopath. 51 (1) : 21-25 (1998) Management of bacterial blight of cotton induced by Xanthomonas axonopodis pv. malvacearum with the use of neem based formulations S.S. HULLOLI, R.P. SINGH and J.

1 Indian Phytopath. 51 (1) : (1998) Management of bacterial blight of cotton induced by Xanthomonas axonopodis pv. malvacearum with the use of neem based formulations S.S. HULLOLI, R.P. SINGH and J.P. VERMA Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi ABSTRACT : The MIC of certain neem based formulations (e.g., plantolyte and agricare) against Xanthomonas axonopodis pv. malvacearum was IJig/ml. This is much lower than the MIC of best antibiotics i.e., aminoglycosides, streptomycin and kanamycin which possess a MIC against Xam of 2.5 Jig/mi. These neem formulations when mixed at concentrations lower than their MIC, at 0.5 Jig/ml, with antibiotics/fungicides, not only reduced their MIC but also completelyinhibited the development of drug resistant mutants, indicating that these neem formulations.acted not only synergistically with antibiotics or fungicides but also reduced their hazardous effects. The neem formulations could control cotyledonary infection alone or in combination with antibiotics at very low doses. It is concluded that neem based formulations have a tremendous potential in an ecofriendly management of bacterial blight of cotton. Key words: Neem, Xd. pv. malvacearum, cotton, management, bacterial blight Plant products, particularly neem (Azadirachta indica) derivatives, are under intensive investigation in search for ecofriendly management practices of plant diseases (Randhawa and Parmar, 1993; Verma et al., 1995). There are no conclusive research data to support the effect of neem products against bacterial diseases (Pandey and Prasad, 1992; Maharishi, 1993; Eppler, 1993). The present work was taken up to generate some data on neem based management of bacterial blight of cotton induced by X. a. pv. malvacearum (Xam). MATERIALS AND METHODS Races of Xam were identified (Verma, 1986) and, in the present studies, race-32 (Xam-R-32) was used because it can neutralise five B-genes (B7' B 4, B 2, BJn and B N ) and is considered the most virulent genotype/ race of Xam present in India. MIC (minimum inhibitory concentration), interaction of chemicals, apoplastic movement of chemicals were studied by cup method, disc diffusion and poisoned food technique (Verma et al., 1975; Nayak and Verma, 1976). The neem based chemicals used were agricare (Agricare, Bangalore, containing neem extract in fortified base, amino nitrogen, protein moiety, polysaccharide, Mg, Zn and Mo), plantolyte (Agricare, Bangalore, containing neem ex- PublicationNo. 2254, Division of Plant Pathology, IARl, New Delhi tract, amino acids, Zn, Mn, Fe, Cu, Mo, B, Mg, Ca and S), neemark (West-Coast Rasayan International Pvt., Bombay), RD-9 (azadirachtin, ITC Ltd., Hyderabad), and an alcoholic extract of neem kernel/seed (Division of Agricultural Chemicals, IARl, New Delhi). RESULTS AND DISCUSSION MIC of individual/mixed resistant mutants chemicals and drug The MIC (as determined by poisoned food technique) of the aminoglycosidic antibiotics (streptomycin, str; and kanamycin, kan) was low (2.5 ug/ml), while the MIC of ridomyl mancozeb and phytolan was 30 and 1000 ug/ml. Both plantolyte and agricare inhibited the growth of Xam at 1 ug/ml, while in case of neemark and alcohol extract of neem seeds the MIC was 20 and 10 ug/ml respectively. RD-9 was ineffective even at 3000 ug/ml. Disc diffusion and cup methods were not suitable for the determination of MIC because no zones of inhibitions were formed even in cases of neemark and alcohol extract of neem seeds (which were effective in the poisoned food technique). However, the efficacy of plantolyte and agricare (MIC of both was 1 ug/ml) was compared by disc diffusion and cup method (Table 1), and in both the cases, plantolyte was more effective. On the basis of the diameter of inhibition zone, 5 ug of plantolyte was equivalent to 30 ug of str, while 10 ug of plantolyte

2 22 Indian Phytopathology [Vol. 51(1) 1998] Table 1. Inhibition zone induced by neem based products (plantolyte and agricare) against Xanthomonas axonopodis pv. malvacearum Sl. No. Concentration Diameter (mm) of inhibition zone produced by (ug/ml) Plantolyte Agricare a b a b II 12 Water (control) so o. 0 0 a = well method, diam of well 10 mm, quantity of solution 0.1 mllwell. b = Paper disc method, diam of disc = 5 mm. was equivalent to 80 J.1gof str; but 5 and 10 J.1gof agricare were equivalent to 10 and 20 J.1gof str, respectively. Neem products were more effective than the best known antiobitics (Verma, 1986), particularly because their MIC was lower than str and they possessed better diffusable properties also. In India, generally pure (single) fungicides have been recommended for the control of plant diseases. But use of mixed antibiotics has started with the use of streptocycline (str + tetracycline) for the control of bacterial diseases (Verma and Singh, 1976). Now a large number of mixed antibiotics and fungicides are known. One of the main reasons for the use of mixed chemicals is to reduce the resurgence of the drug resistant mutants. However, the use of antibiotics like streptomycin or tetracycline, which are most widely used in chemotheraphy of human diseases, should be discouraged (actually banned) in the use of bacterial diseases of plants, except in a few exceptional cases like seed treatment (Verma et al., 1992, 1994, 1995). The replacement of antibiotics is difficult, but a few biocides like oxathin compounds, busan-72, etc., are known which can control bacterial diseases (Verma et al., 1994). The use of botanical pesticides, which are ecofriendly, has not been considered for the management of bacterial diseases of plants. The bactericidal properties of neem products, specially at very low/ comparable concentrations (as antibiotics) as shown in this investigation, are encouraging. Further studies were conducted to determine if these neem products can act synergistically with antibiotics/fungicides and/or reduce their hazardous effects. The MIC of certain mixtures was effective at lower concentrations than the MIC of individual chemicals (Fig. 1) indicating that neem formulations (plantolyte and agricare) have synergistic activity when combined with antibiotics and fungicides. Further, in presence of neem products (plantolyte at 0.5 ug/ml), the development of drug (str) resistant mutants was inhibited-. It is, thus, clear that addition of neem products to chemicals (antibiotics/fungicides) not only reduced their MIC but also eliminated the hazards of the development of the drug resistant mutants. Positive and negative cross resistance is known in Xam (Nafade et al., 1986) and it was also demonstrated (Nafade and Verma, 1984) that addition of ziram to str inhibited the development of str resistant mutants. Effect of neem formulation on the apoplastic movement of chemicals in cotton seedlings The apoplastic movement of various chemicals including antibiotics and systemic fungicides is known

[Vol. 51(1) 1998] Indian Phytopathology 23 2.5 2.0 1.5 (a) 1.0 0 5 0 1 5 P S+P K P K+P K A K+A 5 A StA 1000 800 500 30.0 20.0 10.0 3.0 2.0 1'.

3 [Vol. 51(1) 1998] Indian Phytopathology (a) P S+P K P K+P K A K+A 5 A StA '.0 (b) R P R-+ P F P FtP RA RtA FA FtA RN R+N FN F+N N 5 NtS N K N-+K Fig. 1. MIC of neem products singly and in combination with bactericides (Ia) and fungicides (Ib); S = Streptomycin, P = Plantolyte, K = Kanamycin, A = Agricare, R = Ridomyl mancozeb, F = Fytolan, N = Neemark.. in cotton seedlings (Nayak and Verma, 1976). Certain chemicals like amino acids and organic acids accelerate the translocation while certain other chemicals like ziram almost completely inhibited the translocation of chemicals from hypocotyl to cotyledons. But most of these chemicals did not inhibit the uptake of chemicals by seeds and their translocation to hypocotyl. Studies with botanical pesticides (neem) were taken up to determine whether they inhibit or accelerate the uptake of chemicals by seeds/roots and translocation from roots to hypocotyl or within hypocotyl or from hypocotyl to cotyledons. The control experiments demonstrated that the uptake of str was clearly rapid and the antibiotic reached the cotyledons. within 24 h. It was interesting that at 100 ug/ml of str, there was an accumulation of str in cotyledons (equivalent to inhibition zone produced by 82 ug/rnl of str) within 96 h indicating the rapid uptake and translocation of the antibiotic. Similarly, ridomyl-mancozeb also showed rapid translocation (Table 2) but to a lesser degree than str, because ridomyl mancozeb reached cotyledons only after 72 h (str reached within 24 h) and

4 24 Indian Phytopathology [Vol. 51(1) 1998] Table 2. Effect of neem on uptake and translocation of streptomycin and ridomyl - mz Period of treatment Concentration of mixtures (ug/ml) and their inhibition zone (mm) P(20)+S( I00) P(20)+Rrnz( 100) S(lOO) Rrnz(lOO) P(20) R H C R H C R H C R H C R H C 24 h h h h P - plantolyte, S - streptomycin, R - mz = ridomyl - mz. R = root, H = hypocotyl, C = cotyledon. accumulated at 96 h only to the equivalent of 65 ug/ inhibition zones produced by str in the disc duffusion ml of str (as interpretted by the standard curve of technique). Fig. 2. Effect on cotton seedling dipped in neem products (I) of cotyledonary infection by Xa pv. malvacearum; seedling on left (0) was dipped in Hoagland solution.

[Vol. 51(1) 1998] The translocation of neem products (plantolyte 20 ug/ml) could not be demonstrated by this bioassay technique; it must be, however, mentioned that although no inhibition zones were

5 [Vol. 51(1) 1998] The translocation of neem products (plantolyte 20 ug/ml) could not be demonstrated by this bioassay technique; it must be, however, mentioned that although no inhibition zones were produced, but when the cotyledons were crushed they smelled very strongly of neem products. It was concluded that the translocability of neem products may be demonstrable by some other technique. When the neem products (plantolyte, 20 ug/ml) were added to str (100 ug/ml) and ridomyl-mz (l00 ug/ml), it (plantolyte) strongly inhibited the uptake and translocation of both str and ridomyl-mz (Table 2). At high concentration ofplantolyte (25 u/ml), some phytotoxic effects were apparent. The toxic effects were particularly severe on delicate roots which turned darkblack while the veins in the leaves became very clear or prominent. Use of neem products in the management of cotyledonary infection Under the experimental conditions, it was observed that when the roots of cotton seedlings were dipped in str (200 ug/ml) and the cotyledons inoculated by a virulent XamR-32, symptoms were not produced (Fig. 2). However, inoculation of cotyledons of cotton seedlings dipped in pure Hoagland solution and str at 100 ug/ml produced symptoms, clearly indicating that str was effective in controlling cotyledonary infection at 200 but not at 100 ug/ml (Fig. 2). When neem product (plantolyte, 5 ug/rnl) was added to str (l00 u/ml), there was no symptom. Cotton seedlings dipped in neem product (plantolyte, 100 ug/ml) alone did not develop any symptom. It was concluded that neem products can be used for the management of bacterial blight of cotton. Leaf spot of chilli (X vesicatoriay could be managed by 2% fresh aqueous neem leaf extracts although streptocycline (l00) was superior to neem (Maharishi, 1993). But Eppler (1993) found that aqueous and alcoholic extracts of fresh and dried neem and marrango (Azadirachta excelsa) were not effective against a large number of bacteria including P. syrigae, Agrobacterium tumefaciens, X campestris, Erwinia carotovara, Clavibacter michiganensis, P. jluorescens, B. subtilis, etc. However, bacterial blight of rice (Xo.pv. oryzae) and citrus canker (Xa.pv. citri) could be reduced with Indian Phytopathology 25 the use of a neem cake extract (Eswaramurthy et al., 1993; Mohan and Moses, 1993). REFERENCES Eppler, A. (1993). Untersuchungen zum hemmenden Einfluss von Niem auf Bakterien. Med. Fac. Landbouw.. Univ. Gent 58: Eswaramurthy, S., Mariappan, V., Muthusamy, M., Alaginagalingam, M.N. and Subramanian, K.S. (1993). Efficacy of neem products in controlling bacterial blight of paddy. World Neem Coni. Bangalore, India, p 33 (abstr.). Maharishi, R.P. (1993). Management of chilli (Capsicum annum L.) diseases by neem-based preparations. World Neem Coni. Bangalore, India, p 34 (abstr.). Mohan, C.B. and Moses, G.J. (1993). Effect of extracts of neem and other plants on Xanthomonas campestris citri, the incitant of citrus-canker. World Neem Coni. Bangalore, India, p 41 (abstr.). Nafade, S.D., Verma, J.P. and Singh, R.P. (1986). Interactions between chemicals and bacterial flora of cotton leaves. Ann. Agric. Res. 7: Nafade, S.D. and Verma, J.P. (1984). Effect of chemicals on translocation of streptomycin in cotton seedling. Indian Phytopath. 37: Nayak, M.L. and Verma, J.P. (1976). Uptake and translocation of chemicals in cotton seedling. Z. Pflkrankh. Pjlschutz 82: Randhawa, N.S. and Parmar, B.S. (Eds.) (1993). Neem: Research and Development. Published by Society of Pesticides Science, India, 284pp. Verma, J.P. (1995). Advances in bacterial blight of cotton. Indian Phytopath. 48: Verma, J.P. and Singh, R.P. (1976). Chemical control of bacterial diseases of plants. Chemical Concepts 4: Verma, J.P., Singh, R.P., Jindal, J.K. and Trivedi, B.M. (1992). Bacterial plant pathogens and their management. Fusion Asia 8: Verma, J.P., Singh, R.P., Jindal, J.K., Trivedi, B.M. and Srivastava, Sheela (1994). Plant diseases caused by bacteria. In Botany in India : History and Progress (Ed., Johri, B.M.), pp , Oxford and IBH Pub\. Co. Pvt. Ltd., New Delhi, 521 pp. Received for publication June 17, 1997.

Journal home page:

Journal home page: http://www.journalijiar.com INTERNATIONAL JOURNAL OF INNOVATIVE AND APPLIED RESEARCH RESEARCH ARTICLE Management of bacterial leaf blight of Basmati rice caused by Xanthomonas oryzae