Informatics Publishing Limited

M. Narayana Bhat , R. Jeyarajan , B. Ramaraj

Abstract

In-vitro studies indicated that Rhizopogon leuteolus and Pisolithus tinctorius isolate-2 were highly antagonistic to the mycelial growth of Pythium aphanidermatum, the causal organism for the damping off of Eucalyptus tereticornis. R.leuteolus significantly reduced damping off in pot culture. P.tinctorius and R.leuteolus increased the biomass by 29.3 and 15.1 percent respectively over control.

Full Text

     

K. Renganathan ¹, R. Sridar ¹, R. Jeyarajan ¹

Affiliations
1 Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore - 641 003, IN

Abstract

At present there is considerable pressure from public and environment scientists to go for biocontrol agents, to prevent the environmental pollution caused by pesticides. Use of Trichoderma viride Pers.exfr, was reported to be effective in reducing the propagules of seed as well as soil-borne pathogens (Papavizas, 1984). Ramakrishnan et al. (1994) developed a talc-based product of T. viride. Jeyarajan et al. (1994) reported that the talc-based T. viride when used for seed treatment @ 4 g/kg seed reduced the ischolar_main rot of pulses and oilseeds. The cost of the talc powder is Rs.10/kg which has a major share in the production cost of Trichoderma product.

Keywords

Trichoderma viride, Formulation, Gypsum.

Full Text

   

G. Ramakrishnan ¹, R. Jeyarajan ¹, D. Dinakaran ¹

Affiliations
1 Department of Plant Pathology, Tamil Nadu Agricultural University Coimbatore 641 003, IN

Abstract

A simple formulation of Trichoderma viride Pers ex. S.F. Grey for seed pelleting was developed by mixing tale powder with Trichoderma biomass obtained by growing the fungus in molasses-yeast medium for 15 days and drying. For effective adherence to the seeds CMC was added @ 0.5 % leveJ after drying. This formulation packed in polythene bags yielded 8 x 10⁷ colonies/g after 120 days. Seed treatment with this product effectively reduced the ischolar_main rot diseases of urd bean (Vigna mungo {L.} Hepper caused by Macrophomina phaseolina (Tassi) Goid. both in the artificially infested soil and natural soil in farmers fields.

Keywords

Macrophomina phaseolina, Biocontrol, Trichoderma viride, Talc-Based Formulation, Vigna mungo.

Full Text

   

R. Sridar ¹, G. Ramakrishnan ¹, D. Dinakaran ¹, R. Jeyarajan ¹

Affiliations
1 Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore 641 003, IN

Abstract

Bacillus subtilis has been used for many years to control soil-borne plant pathogens and increase plant growth (Turner and Backman, 1991). The increased yield of urdbean (Vigna mungo) due to Rhizobium application has been reported by Balasubramanian and Palaniappan (1983). B. subtilis seed treatment also improved the crop stand and yield (Merriman et al., 1974). Therefore, studies were conducted to assess the effect of seed treatment with antagonists on the nodulation and ischolar_main rot incidence.

Keywords

Rhizobium, Antagonist, Bacillus subtilis, Nodulation, Root Rot.

Full Text

   

R. Sridar ¹, G. Ramakrishnan ¹, D. Dinakaran ¹, R. Jeyarajan ¹

Affiliations
1 Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore, 641 003, IN

Abstract

Bacillus subtilis (Cohn) has been used for many years to control plant pathogens and to increase plant growth (Turner and Backman, 1991). This bacterial antagonist is known to produce extracellular antibiotics, that are inhibitory to some plant pathogens (Podile et al., 1988). A commercial preparation of B.subtilis A.13 has been developed under the trade name Quantum 4000 and is recommended for treatment of peanut seeds for the control of soil borne diseases (Weller, 1988). With the intention of developing an inexpensive B. subtilis inoculant that can be easily applied, an experiment was conducted in our laboratory.

Keywords

Bacillus subtilis, Carriers, Formulation.

Full Text

   

Kousalya Gangadharan ¹, R. Jeyarajan ¹

Affiliations
1 Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore-641 003, IN

Abstract

Biological control of plant pathogens through antagonistic microorganisms is a promising alternative to the use of chemicals. One of the critical obstacles in biological control of plant pathogens is the paucity of methods for mass culturing and applying the antagonists to the soil. Mukhopadhyay (1987) has comprehensively reviewed the various growth media used for mass multiplication of Trichoderma spp. The present investigations were carried out to identify suitable substrates among the agricultural by-products and wastes for mass multiplication of Trichoderma viride Pers. Fr. and T. harzianum Rifai.

Keywords

Trichoderma viride, T. harzianum, Macrophomina phaseolina, Biological Control.

Full Text

   

L. Mohan ¹, R. Jeyarajan ¹

Affiliations
1 Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore- 641 003, IN

Abstract

Ergot of pearl millet (Pennisetum americanum (L.) Leeke) caused by Claviceps fusiformis Loveless is causing severe losses in several high yielding varieties and hybrids of pearl millet in India. In addition to direcly reducing grain yield, the admixture of sclerotia with grain poses a health hazard to consumers because of a toxic alkaloid. The methods of management of the disease include removal of sclerotia from the seed prior to planting by floatation in 10% salt solution, post harvest deep ploughing to bury sclerotia and adjustment of sowing time to avoid conditions conducive to infection. However, these methods do not give the desired level of disease control (Thakur et al., 1985). Since the sclerotia constitute the primary source of inoculum, their destruction will reduce the perpetuation of the disease. Since the fungicides are not effective in this direction, antagonistic fungi like Gliocladium virens Miller and Foster, Trichoderma viride Pers and T. harzianum Rifai were tested to find out whether the germination of sclerotia can be delayed or inhibited by them. Kulkarni and Moniz (1974) reported that Cerebella andropogonis inhibited the sclerotial development of ergot of bajra. In this pathogen, Tripathi et al. (1981) reported that Fusarium sembucinum Fuckel and Dactylium fusariodes majus Wollen W., parasitized honeydew and sclerotial stages.

Keywords

Ergot, Mycoparasites, Biological Control.

Full Text

   

M. Muthamilan ¹, R. Jeyarajan ¹

Affiliations
1 Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore - 641 003, IN

Abstract

In vitro studies showed that 67.4 percent reduction of sclerotlal production in Sclerotium rolfsii was observed in the presence of Trichoderma viride Pers. (isolate 2). Mature sclerotia from each dual culture plate measured 647, 777, and 763 μm with T. viride (isolate 3), T. harzianum Rifai (isolate2) and Laetisaria aravalis Burdusall respectively. In slide germination test, 68.3 and 56.7 percent reduction of sclerotial germination was observed with T. viride (isolate 3) and T. harzianum (Isolate 2), respectively; whereas when plated in solid media, it was 47.5 percent with T. viride (isolate 3). The number of hyphae put forth by each sclerotium was found to be minimum in sclerotia produced in dual culture with T. viride (isolates 2 and 3).

Keywords

Trichoderma viride, T. harzianum, Laetisaria arvalis, Dual Culture, Incubation, Germination.

Full Text

   

C. Kurvilla Jacob ¹, K. Sivaprakasam ¹, R. Jeyarajan ¹

Affiliations
1 Department of Plant Pathology, Tamil Nadu Agricultural University, Coimbatore, IN

Abstract

Eight fungal antagonists and eight leaf extracts were evaluated in vitro against Pythiun aphanidermatum (Edson) Fitzpatrick and the effective treatments selected for pot culture evaluation. Pot culture studies with brlnjal seeds showed that Eucalyptus leaf extract as seed soak treatment for 30 minutes prior to sowing was effective against P. aphanidermatum. Seed treatment with Trichoderma harzianum at 5 × 10⁹ conidia per ml, Lactisaria arvalis at 0.66 mg sclerotia per ml and Captan at 0.25 per cent also effectively controlled P. aphanidermatum.

Keywords

Plant Extracts, Fungal Antagonists, Biological Control, Damping off Brinjal.

Full Text