Possible management of Fusarium wilt of tomato by soil amendments with composts

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Indian Phytopath. 50 (3) : 387-395 (1997) Possible management of Fusarium wilt of tomato by soil amendments with composts HARENDER RAJ*

1 Indian Phytopath. 50 (3) : (1997) Possible management of Fusarium wilt of tomato by soil amendments with composts HARENDER RAJ* and I.J. KAPOOR Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi Abstract: Five different composts viz., banana leaves, bagasse, synthetic mushroom compost, paddy straw and spent mushroom compost at 0.5, 1.0 and 2% of soil (w/w) have been used as soil amendments to determine their influence on the population of tomato wilt pathogen (Fusarium oxysporum f. sp. Iycopersici (Sacc.) Suyder and Hansen), soil microflora, disease incidence and plant growth in transplanted tomato plants in pots (cv. 'Pusa Ruby'). The various composts used in the present investigation (6 weeks after transplant) reduced disease index by 44-74%, brought down disease incidence from 89% in the control plants to 4-72% in treated plants and mortality by %. The composts, in general, enhanced microbial activity (total fungi and bacteria) in amended soils resulting in reduction in inoculum density and capacity as well as better plant growth (in terms of shoot and root lengths) and disease control. Banana leaves, mushroom and bagasse composts (2%, w/w) were most effective in reducing the mean inoculum load by more than 78 (78.2 to 80.5) per cent and increasing total fungal and bacterial population in the soil by 56.6 and 69.2 (mean 62.2), and 42.7 and 61 (mean 48.8) per cent, respectively, indicating enhanced microbial activity. These composts (at 2% concentration) reduced disease index by 67 to 74%, disease incidence by 44-96% (maximum in banana leaves compost) and prevented mortality completely. Composts, in general, exhibited stronger protection at higher than at lower concentrations. Keywords : Management, tomato, wilt, Fusarium oxysporum f. sp. lycopersici, organic amendments, composts Soil borne pathogens cause heavy losses to most agricultural crops. Tomato wilt caused by Fusarium oxysporum f. sp. lycopersici (F.o.!.) is a typical example and is a serious disease wherever the crop is grown in India (Kapoor, 1988). Chemical, biological and physical methods being less in use owing to their obvious limitations against soil borne pathogens, the amendments of Received for publication May 3, Present address : Regional Horticultural Research station, Jachh, Tehsil Nurpur, Distt. Kangra, H.P Publication No MPP, larl, New Delhi 1IO 012. soil with decomposable organic matter is an effective method of changing the soil and rhizosphere environment. Composts enrich the soil with microflora potentially competitive or antagonistic to pathogens or release inhibitory substances or volatiles during decomposition. Composts have been in vogue in agriculture with beneficial effects for years in China, Japan and other parts of the world (Kelman and Cook, 1977; Hoitink and Fahy, 1986). In the present studies, five composts have been used as soil amendments to observe their influence on pathogen population, soil rnicroflora, disease incidence and tomato plant growth. MATERIALS AND METHODS Five composts, viz., bagasse, banana leaves, paddy straw (obtained from Dr. R.S. Mathur, Div.

2 388 Indian Phytopathology of Microbiology, IARI, New Delhi), mushroom compost and spent mushroom compost (obtained from Dr. N. Bahl, Div. of Plant Pathology, IARI, New Delhi) were employed in the present studies. The composts obtained from Dr. R.S. Mathur were prepared in the following manner (personal communication). The e/n ratio of chopped air dried compost substrates were adjusted to 60:1 (especially of paddy straw and bagasse from sugarcane industry) by adding requisitie amount of nitrogen (as urea). Basal inoculation with rock phosphate at 1% (w/w) was also done. Moisture content was maintained at 80% for each substrate. Two kg of each residue was filled into high density polythene bags. Small holes were made with a pin throughout the bag for aeration for the metabolising microorganism. The compost material were inoculated with efficient cellulytic fungi (Trichoderma sp.) and thus the compost were ready in 60 days. The mushroom compost (synthetic) was prepared by the methods laid down by Bahl (1991). The exhausted compost left over after taking the last harvest of mushroom was taken as spent mushroom compost. The formaldehyde sterilized soil was infested with the vigorously growing culture (4 weeks old) of Fo.l. (DFo-13) onsand-maize-meal medium in the ratio of 1:4, inoculum : soil (Raj and Kapoor, 1996). Different composts were incorporated at 0.5, 1.0 and 2.0% of soil (w/w) in the upper 15 em of the pathogen infested and uninfested soil. Pots were watered regularly and the population count of the test fungus, Eo.l., and other microorganisms, viz., total fungi and bacteria was counted upto 60 days at 20 days interval using Fusarium specific (Nash and Snyder, 1962), Steiner and Watson (1965) and Farley and Lockwood (1968) agar media, respectively, by dilution plate technique (Barron, 1971). Subsequently, 30 days old six tomato seedlings of cv 'Pusa RJIby' were transplanted in each pot to observe the effect on disease severity. The wilt incidence was recorded six weeks after transplantation. The disease incidence, percentage mortality, disease control as well as percentage reduction in shoot and root length were [Vol. 50(3) 1997] calculated by the methods elaborated by Raj and Kapoor (1993, 1996). All treatments were replicated thrice and corresponding controls were maintained in all the cases unless otherwise stated. RESULTS AND DISCUSSION Effect of different composts on soil population of F. oxysporum f.sp. /ycopersici All composts significantly reduced the inoculum load of Eo.l. in soil, the reduction ranging 'between 38.2 and 80.5% over control (Table I). Bagasse compost was found most effective in reducing the inoculum load of the test fungus to a level of 7.3x103 g' from 37.5xI03g'! in controls, thereby registering a reduction of 80.5% at 2.0% concentration. Bagasse, banana leaves and mush-.room composts were statistically at par at this concentration. Bagasse compost was significantly more effective at 1% concentration also. In general, all composts gave good response at as low a concentration as 0.5% (reduction in pathogen population ranging between 38.2 and 47.9%) but higher dosages i.e. 1% (reduction being 57.7 and 69.2%) and above (reduction 72.2 and 80.5%) were significantly more effective in reducing the soil population of the tomato wilt patogen. The order of reduction in disease incidence and disease index was similar to that observed in case of reduction of inoculum load in soil at various concentration of composts. Decomposition of composts in soil for a longer period (60 days) was found to be most appropriate for bringing down the viable propagules of the pathogen in soil. This can be illustrated by viewing the mean inoculum load at 20 and 60 days after mixing the compost, being 16.8x10 3 g'!and 13.6xl0 3 g'!, respectively. Papavizas (1968) reported reduction in inoculum density of bean root rot pathogen (Thielaviopsis basicola) in soils amended with barley straw, cabbage leaves and stems, oat straw, com stover and alfalfa hay. Effective reduction in number of sclerotia of stalk rot of cauliflower (Sclerotinia sclerotiorum) by spent mushroom has been re-

3 [Vol. 50(3) 1997] ported by Gupta et al. (1986). Effect of different composts on microbial population of soil The reduction in inoculum load by various composts was found associated with increase in other soil microflora. All composts generally enhanced fungal population in soil in comparison to control (Table 2). Bagasse compost, with a popu- Indian Phytopathology 389 lation count of26.9 x 104g-1, was most effective in supporting the fungal population followed by mushroom and banana leaves compost at 2% concentration with a non- significant difference among themselves. These composts increased the mean fungal population between 57 and 69% at 2% concentration over control. The corresponding increase in spent mushroom and paddy straw composts was 26 and 37% only. Of all the composts, Table 1 : Effect of different composts on soil population of F. oxysporum f.sp. /ycopersici *Number of propagaules in lq3g-1soil Compost Concentration at days after mixing the compost (per cent) (w/w) Banana leaves Bagasse Paddy straw Mushroom compost Spent mushroom compost Mean Mean Control (Inoculated) 37.5 Source S.Em. ± C.D. 5% Compost Cone Days Interaction (Compost x Cone x Days).Initial Inoculum 31.7 x 1Q3g-1soil.

4 390 Indian Phytopathology bagasse, banana leaves and mushroom composts were found statistically at par at all the concentrations. However, decomposition of composts for 60 days significantly increased the fungal population in soil. Different composts significantly influenced the soil population of bacteria also (Table 3). Bagasse compost was found most effective with highest population of soil bacteria (38.1 x 10 5 g") followed [Vol. 50(3) 1997] by banana leaves, mushroom, spent mushroom and paddy straw composts at 2% concentration. Increase in compost concentration and decomposition time significantly increased soil population of bacteria. These results, therefore, indicate that addition of composts to the soil, in general, and especially of bagasse, banana leaves and mushroom composts increased the soil micro flora by support- Table 2 : Effect of different composts on fungal population of soil *Number of propagaules in 10 4 g" soil Compost Concentration at days after mixing the compost (per cent) (w/w) Banana leaves Bagasse Paddy straw Mushroom compost Spent mushroom Compost Mean Mean Control (inoculated) 15.9 Source S.Em. ± C.D.5% Compost Cone Days Interaction (Compost x Cone x Days) *Initial fungal load x 10 4 g" soil.

5 [Vol. 50(3) 1997] Indian Phytopathology 391 ing higher population of fungi and bacteria as well as causing more reduction in the soil population of F The antagonists/saprophytes which compete for the nutrients with the soil borne pathogens thus might have affected the multiplication of tomato wilt pathogen in soil adversely which could be one of the reasons of low build up of pathogen in compost amended soils. Our observations get further support from the findings of several workers. Gilbert et al. (1968) were of the opinion that the rise in population of total fungi and bacteria ultimately suppress growth of patho- Table 3 : Effect of different composts on soil population of bacteria Compost *Number of propagules in 10 5 g o1 soil at days after mixing the compost Concentration (per cent) (w/w) Mean Banana leaves Bagasse Paddy straw Mushroom compost Spent mushroom compost Mean Control (inoculated) 23.7 Source S.Em. ± C.D.5% Compost Cone Days Interaction (Compost x Cone x Days) *Initial bacterial load 19.7 x 10 5 gol soil.

392 Indian Phytopathology genic forms, whereas Singh and Pandey (1967) suggested that organic amendments are known to increase fungal activity in soil. Gugino et. al.

6 392 Indian Phytopathology genic forms, whereas Singh and Pandey (1967) suggested that organic amendments are known to increase fungal activity in soil. Gugino et. al. (1973) also reported that increase in total population of fungi, bacteria and actinomycetes was associated with decrease in population dynamics of Pythium irregulare in 100 per cent pinebark media. Effect of composts on disease severity Five composts were tested at three concentra-, tions to determine their effect on disease severity. It was observed (six weeks after transplantation) that, in general, all composts had substantial positive influence on the reduction of disease related parameters. The composts reduced disease index by 44-74% and brought down disease incidence [Vol. 50(3) 1997] from 89% in the control plants to 4-72% and mortality by % in treated ones. While analysing effect of different concentrations of composts, the various composts brought down wilting from 89% in the control plants to 4-50 (mean 38%), 6-61 (48%), (66%) in the treated plants; reduced disease index by (71%),51-64 (58%), (50%) and mortality by 100 (100%), (98%) and (85%) at 2.0, 1.0 and 0.5% concentration, respectively. Thus, higher dosage (2%) of composts exhibited better disease controlling potentiality followed by 1.0 and 0.5% concentrations, in that order (Table 4). When all the concentrations of different composts are viewed together, the reduction in disease incidence was maximum (73.5%) in banana leaves compost and minimum in spent mushroom compost Table 4 : Effect of soil amendments with different composts on the severity of tomato wilt (Fusarium oxysporum f.sp. /ycopersici), recorded after six weeks of transplantation Trreatmentsl Concentration Disease Mean disease Mortality composts (%, w/w) incidence index (%) (%) (0-5) Banana leaves Bagasse Paddy straw Mushroom Spent mushroom compost Control (inoculated) Results are based on 18 plants per concentration/treatment.

7 [Vol. 50(3) 1997] (31.5%), whereas reduction in disease index was maximum in three composts, viz., bagasse, banana leaves and mushroom composts ranging from 61-64% and minimum (55%) in spent mushroom compost. The difference in effect of various composts was reflected not so much in mortality as in disease incidence and disease index. Composted larch bark is successfully used in Japan by vegetable growers for the control of Fusarium brown rot of Chinese Yam (Sekiguchi, 1977). Tree bark compost provided a high degree of control of straw- Indian Phytopathology 393 berry red stele caused by Phytophthora fragriae (Vaughn et al., 1954). In Taiwan, many plant diseases caused by Fusarium spp. were effectively controlled by using composts and mineral mixture (Sun and Huang, 1985). Effect of composts on plant growth The plant growth in terms of shoot and root length was affected in all compost amended treatments including inoculated ones as compared to uninoculated controls (Table 5). However, per cent Table 5 : Effect of composts on the growth of tomato plants raised in soil infested with F. oxysporum f.sp. lycopersici Compost Concentration *Per cent reduction over uninoculated (per cent) control (w/w) Shoot length Root length Banana Bagasse Paddy leaves straw (31.7) 44.4 (41.8) (27.3) 37.0 (37.4) (20.0) 14.9 (22.7) (34.0) 40.7 (39.6) (30.5) 32.6 (34.8) (18.5) 12.0 (20.2) (35.4) 43.3 (41.1) (30.5) 35.8 (36.7) (22.6) 20.2 (26.6) Mushroom compost (36.6) 39.3 (38.8) (29.1) 29.9 (33.2) (20.3) 12.9 (21.0) Spent mushroom compost (41.3) 45.1 (42.1) (35.4) 33.1 (35.1) (25.2) 20.1 (26.5) Control (inoculated) 50.8 (45.5) 47.4 (43.5) Source Compost Cone Interaction (Compost x Cone) S.Em. ± C.D.5% Figures in parentheses are transformed 'Arc Sine' values. (Av. of 5 replicates) S.Em. ± C.D. 5%

394 Indian Phytopathology reduction in shoot and root length, varying between 10 and 43.7 (mean 24.7), and 12 and 45.1 (mean 30.7) respectively, was less in compost amended soil in comparison to.50.

8 394 Indian Phytopathology reduction in shoot and root length, varying between 10 and 43.7 (mean 24.7), and 12 and 45.1 (mean 30.7) respectively, was less in compost amended soil in comparison to.50.8 (shoot) and 47.4 (root) in inoculated controls thereby showing a positive influence of composts on plant growth. Further, all composts at all dosages supported better growth of shoot and root in comparison to inoculated controls, the improvement in shoot and root being 64.4 to 80.2 and 57.4 to 74.8%, respectively. Bagasse compost was most effective followed by mushroom compost and banana leaves compost. Spent mushroom compost was least effective registering an improvement in shoot length by 64.4% followed by paddy straw compost (70.7%) at 2% concentration with a significant difference among themselves, These composts were also least effective as the root growth improved by 42.3 to 57.4% only. Higher dosage of composts were most effective and significantly improved plant health when the development of both shoot and root are considered together. Similar type of results have been reported with S-H mixture in Fusarium wilt of watermelon, where S-H mixture amended soils supported higher length of vines (Sun and Huang, 1985). Of all the composts, three composts, viz., bagasse, banana leaves and mushroom compost have almost similar effect in enhancing the microbial activity in the amended soil and the higher dosage (2%, w/w) of composts are most effective in managing the pathogen (reduction in inoculum density and capacity), thereby resulting in better plant health and disease control (when all the parameters are viewed together). Thus, it could be concluded from the present studies that the effectiveness of composts used as soil amendments in controlling the disease could possibly be due to enhanced activity of other non-parasitic microbes (fungi/bacteria) providing antagonism to the tomato wilt pathogen and/or decomposition products of composts being non- favourable for the multiplication of the inoculum. ACKNOWLEDGEMENTS [Vol. 50(3) 1997] The authors are grateful to Dr. R.S. Mathur, Principal Scientist, Division of Microbiology, and Dr. Nita Bahl, Senior Scientist, Division of Plant Pathology, IAR!, New Delhi, for providing compost material for the present studies. The assistance rendered by Mr. O.P. Singh, Technical Officer, Division of Plant Pathology, IAR!, New Delhi, is appreciated. REFERENCES Bahl, N. (1991). Technology for the cultivation of mushroom. Information Bulletin-1991, Division of Mycology & Plant Pathology, Indian Agricultural Research Institute, New Delhi-l Barron, G.L. (1971). Soil fungi. In : Methods in Microbiology, 4 (Ed., Booth, C.) Academic Press, London, 405 pp. Farley, J.D. and Lockwood, J.L. (1968). The suppression of actinomycetes by PCNB in culture media used for enumerating soil bacteria. Phytopathology, 58: Gilbert, R.G., Menzies, J.D. and.griebel, G.E. (1968). The influence of volatile substances from alfalfa on growth and survival of Verticillium dahliae. Phytopathology, 58 : Gugino, J.L., Pokoorny, F.A. and Hendrix, F.F. (Jr.) (1973). Population dynamics of Pythium irregulare Buis in container plant production as influenced by physical structure of media. Plant Soil, 39: Gupta, S.K., Agarwala, R.K. and Sharma, S.L. (1986). Efficacy of soil amendments in managing stalk rot (Sclerotinia sclerotiorum) of cauliflower. Indian J Plant Pathol. 4: Hoitink, H.A.J. and Fahy, P.c. (1986). Basis for the control of soil borne plant pathogens with compost. Ann. Rev. Phytopathol. 24: Kapoor, I.J. (1988). Fungi involved in tomato wilt syndrome in Delhi, Maharashtra and Tamil Nadu. Indian Phytopath. 41: Kelman, A. and Cook, R.J. (1977). Plant pathology in the People's Republic of China. Ann. Rev. Phytopathol. 17:

9 [Vol. 50(3) 1997] Nash, S.M. and Snyder, W.e. (1962). Quantitative estimation of plate counts of propagules of the bean root rot Fusarium in field soil. Phytopathology, 51: Papavizas, G.e. (1968). Survival of root infecting fungi in soil. VI. Effect of amendments on bean root rot caused by Thielaviopsis basicola and inoculum density of the causal organisms. Phytopathology, 58: Raj, H. and I.J. Kapoor (1993). Soil solarization for the control of tomato wilt pathogen (Fusarium oxysporum Schl.). Z. PjlKrankh. PjlSchutz. 100: Raj, H. and I.J. Kapoor (1996). Effect of oil cake amendment of soil on tomato wilt caused by Fusarium oxysporum f.sp. lycopersici. Indian Phytopath., 49: J. Sekiguchi, 1\.. (1977). Control of Fusarium wilt on Indian Phytopathology 395 Chinese Yam. Ann. Rep., Dep. Plant Pathol. Entomol. Veg. Floric. Exp. Stn., Nagano, Japan, 1: Singh, R.S. and Pandey, K.R. (1967). Population dynamics of Pythium aphanidermatum in soil cake amended soil. Ca. 1. Microbiol. 13: Steiner, G.W. and Watson, R.D. (1965). Use of surfactants in the soil dilution and plate count method. Phytopathology, 55: Sun, S.K. and Huang, J.W. (1985). Formulated soil amendment for controlling Fusarium wilt and other soil borne diseases. Plant Dis. 69: Vaughn, E.K., Roberts, A.N. and Mellenthin, W.M. (1954). The influence of Douglas fir sawdust and certain fertilizer elements on the incidence of red stele disease of strawberry. Phytopathology, 44: \

Production of Composts with Broad Spectrum Disease Suppressive Properties Harry A.J. Hoitink

Production of Composts with Broad Spectrum Disease Suppressive Properties Harry A.J. Hoitink Professor Emeritus Dept. of Plant Pathology The Ohio State University, Wooster TOPICS Fate of pathogens during