Browsing by Author "Girija, V K"

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Biological control of foot rot of black pepper with antagonstic bacteria from rhizosphere
(Department of Plant Pathology, College of Agriculture, Vellayani, 1997) Jubina, P A; Girija, V K
An attempt was made at the Department of Plant Pathology, College of Agriculture, Vellayani to screen and identify antagonistic soil bacteria with potentiality to suppress Phytophthora capsici, the incitant of foot rot or quick wilt of black pepper. Bacteria were isolated from the rhizosphere of wild pepper plants, pepper plants in disease free plantations, healthy plants in diseased pepper plantations, pepper plantations where organic farming is practiced, undisturbed forest soils and vermicompost. Population of bacteria in the various 50ils and vermicompost showed great variability ranging from 13.67xl04 to 168xl04 cfu g-1. High population of bacteria was recorded from the rhizosphere soils of healthy plants in diseased pepper plantation of Pepper Research Station, Panniyur and wild pepper plants in virgin forest of Punnamala region of Silent Valley. Of the 194 isolates, only 15 isolates showed antagonism to P. capsici in vitro. Three isolates B5, B7 and Bl3 were highly effective in in vitro inhibition of sporangial production by the pathogen and disease suppression in rooted cuttings of the susceptible pepper variety, Karimunda. Isolate B13 was found to be the most ideal candidate with the ability to reduce mortality of pepper plants and foliar blighting and to provide continued protection for a longer period. The isolate was effective as cell free filtrates also and was found to produce small quantities of the enzyme, cellulase. Isolate B5 also reduced the disease in pepper plants. The live cells and cell free filtrate of this isolate afforded good foliar protection against P. capsici. The isolate B7 was found to have a dual role disease suppression and growth promotion. All these isolate~ had good survival in the rhizosphere of pepper plants with population of 104 to 105 cfu g-l soil. The effective isolates were gram positive, aerobic, sporulating, rods with ability to produce catalase and were found to conform to genus Bacillus.
Choanephora pod rot of cowpea and its ecofriendly management
(Department of Plant Pathology, College of Agriculture, Vellayani, 2015) Milsha, George; Girija, V K
The study entitled “Choanephora pod rot of cowpea and its ecofriendly management” was undertaken in the Department of Plant Pathology, College of Agriculture, Vellayani during 2013-2015 with the objective to study the symtomatology, etiology and to develop an ecofriendly management strategy for Choanephora pod rot of cowpea. The pathogen causing the pod rot of cowpea was isolated from the diseased pods, leaves, peduncle, stem and flowers. Pathogenicity was proven following Koch’s postulates, virulence rating was done and the C3 isolate obtained from cowpea pods were found to be the most virulent isolate. Based on cultural and morphological characters, the pathogen was identified as the Choanephora cucurbitarum (Berk. &Ravenel) Thaxt., which was further confirmed by ITS sequencing. The study revealed that the C. cucurbitarum had wide host range encompassing other vegetable crops such as bhindi, cucurbits, chilli, amaranthus and brinjal. Natural incidence of the disease was not observed on any weeds in and around the cowpea fields. However, on artificial inoculation of the pathogen, the spreading hogweed (Boerhaavia diffusa L. Noms. Cons) took up infection. The dual culture technique to study the antagonism of the saprophytic mycoflora isolated from the rhizosphere and fructosphere through serial dilution and plating indicated that Trichoderma virens and Pseudomonas fluorescens exhibited 79.50% and 55% percentage inhibition of the pathogen. The effectiveness of organic preparations such as panchagavya, jeevamruth, fish amino acid, vermiwash and compost tea was tested at different concentrations by poisoned food technique. Amendment of media was also done with autoclaved and filtered organic preparations. Vermiwash at 2.5%, 5% and 10% filtered as well as incorporated to media as such, significantly suppressed C.cucurbitarum. Jeevamruth (10%) and Panchagavya (10%) gave complete inhibition of the pathogen. Panchagavya (10%) incorporated after filtration and autoclaving also gave 100% and 94.4% suppression of the pathogen respectively. The application of effective dose of organic preparations on excised pods showed that panchagavya (10%) caused maximum suppression of pod rot (60.64%). Among the biocontrol agents, the selected bacterial antagonist i.e., P. fluorescens showed complete suppression of the disease when applied on the excised pods. A pot culture study was conducted to evaluate the efficiency of organic preparations, biocontrol agents and fungicides. The maximum disease suppression of 99.72% was observed in plants sprayed with copper hydroxide. The organic preparation, fish amino acid suppressed the disease to 87.33%. Application of effective biocontrol agent T. virens yielded 75.27% suppression of pod rot. The ecofriendly management of the disease can be achieved by application of fish amino acid (10%) or T. virens (106cfu/ml) or fungicides such as copper hydroxide (0.2%), mancozeb (0.3%) and propiconazole (0.1%) during the pod formation stage.
Effect of certain plant protection chemicals on the incidence of VA mycorrhiza in black gram
(Kerala Agricultural University, 1991) Nair, S K; Girija, V K; Kamala Nayar
Host varietal specificity rhizhobium for nodulation in ground nut
(Kerala Agricultural University, 1988) Girija, V K; Nair, S K
Integrated management of fusarium wilt and anthracnose of vegetable cowpea (Vigna unguiculata subsp. sesquipedalis (L.) Verdcourt) using new generation fungicides
(Department of Plant Pathology, College of Agriculture, Vellayani, 2014) Sreeja, S J; Girija, V K
Integrated management of fusarium wilt of vegetable cowpea (Vigna unguiculata sub sp. Sesquipedalis (L.) Verdcourt)
(Department of Plant Pathology, College of Agriculture, Vellayani, 2003) Senthil Kumar, E; Girija, V K
Management of collar rot and web blight of cowpea with composts and compost teas
(Department of Plant Pathology, College of Agriculture, Vellayani, 2014) Arathy Rajan; Girija, V K
The study entitled “Management of collar rot and web blight of cowpea using composts and compost teas” was undertaken at the Department of Plant Pathology, College of Agriculture, Vellayani with the objective of developing an eco-friendly management strategy. The pathogen causing the disease was isolated from the collar rot and web blight affected parts and identified as Rhizoctonia solani Kuhn. Pathogenicity was proved following Koch’s postulates and the virulent isolates were identified. Collar rot and web blight isolates of R. solani were found to be cross infective. Neem leaf was found to significantly suppress the collar rot and web blight isolates of the pathogen and was selected for the preparation of leaf compost. Studies on the effect of dilution and brewing time of compost tea indicated that 1:5 dilution brewed for a period of 24 h showed maximum fungal population and was adopted for the preparation of compost teas. The dual culture technique to study the antagonistic potential of the saprophytic fungi isolated from composts against R. solani revealed that Trichoderma sp. exhibited the maximum inhibition. Based on the cultural and morphological studies, the antagonist was identified as Trichoderma virens and was selected for enrichment of composts by inoculating @ 100 ml/ kg compost. Enriched compost teas were prepared from the enriched composts. The effectiveness of composts, compost teas and their enriched forms on the incidence of collar rot and intensity of web blight were assessed in a pot culture experiment. The incidence of collar rot was lowest in soil incorporated with neem leaf compost and Trichoderma enriched neem leaf compost tea. Similarly, the percentage suppression of web blight disease was higher in soil sprayed and drenched with Trichoderma enriched neem leaf compost tea. The application of Trichoderma enriched neem leaf compost tea recorded a higher value for biometric parameters. The present study indicated that the composts and compost teas offer eco-friendly management of collar rot and web blight along with crop growth promotion. The effect can be further augmented by enriching with Trichoderma.
Management of collar rot of cowpea caused by rhizoctonia solani kuhn using biofumigants
(Department of Plant Pathology, College of Agriculture, Vellayani, 2017) Aparna, K P; Girija, V K
New leaf and sheath blight disease of ribbon grass
(Kerala Agricultural University, 1993) Girija, V K; Naseema, A; Wilson, K I
Occurrence of vesicular-arbuscular mycorrhiza in certain crop plants of Kerala
(Kerala Agricultural University, 1985) Girija, V K; Nair, S K
Sensitivity of blue green algae to soil reaction - A factor affecting its efficient use as biofertilizer
(Kerala Agricultural University, 1993) Nair, S K; Shehana, R S; Girija, V K; Meenakumari, K S
Studies on host-varietal specificity for Rhizobium for nodulation in groundnut
(Department of Plant Pathology, College of Agriculture, Vellayani, 1982) Girija, V K; Sasi Kumar Nair
An investigation was carried out at the College of Agriculture, Vellayani, Kerala to study the host-varietal specificity, if any, for Rhizobium for nodulation in groundnut. A total of fifteen groundnut varieties were subjected to a preliminary screening on the basis of the number of nodules formed and arranged into five distinct nodulation groups. Seven varieties of groundnut TMV-12, USA-123 Exotic-6, Spanish Peanut, TMV -11, Ak12-24 and Ah-32 were selected from among these groups for use in further studies.