Browsing by Author "Sheela, M S"

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Bioecology and management of root-knot nematode Meloidogyne incognita chitwood in kacholam Kaempferia galanga Linn
(Department of Entomology, College of Agriculture, Vellayani, 1998) Rajani, T S; Sheela, M S
The biology of root-knot nematode of kachlolam, its histopathological effects on roots and the effect of soil type on the pathogenicity of M. incognito infesting kacholam were studied under pot culture conditions. The effect of soil moisture and pH on the hatching of eggs and survival of larvae were studied in vitro in micro pots. Field trials were carried out to assess the crop loss and to find out a suitable management strategy for the root-knot nematode infesting kacholam. The root-knot nematode, Miincognita took 37 days for the completion of one life cycle in kacholam plants at room temperature of 27 + or - 3 0 C and the mean number of eggs observed per egg mass was 130. In kacholam roots, the nematode mainly infests the xylem vessels. The giant cells were quadrangular in shape and three in number and were observed adjacent to the head of the nematode. Field capacity was the most favourable soil moisture level for the hatching of eggs and survival of larvae of M.incognita. There weas no statistically significant variation in the hatching of eggs and survival of larvae under different soil pH levels ranging from 5 to 7.5. Sandy soil (Entisol) was found to be the best soil type for the multiplication of M. incognita infesting kacholam roots. The biometric characters and yield were reduced with the increase in inoculum levels and a maximum reduction was noticed at 10,000 12 level in all soil types under pot culture conditions. At field conditions, inoculation of 1000 12 per plant resulted in the reduction of number of leaves, rhizome length, root weight and yield per plant and per plot yield to the tune of 43.33,23.71,46.26,63.69 and 43.46 per cent respectively over control plants. Neem cake 200 g/m2, V AM (Glomus fasciculatumy 300 g/m2 inoculum per plant and cabofuran 3.33 g/ m2 were found effective for the management of root-knot nematode, M. incognita infesting kacholam.But neem cake treatment was found to be the best in reducing the soil and root population of nematodes and increasing the plant growth characters (number of leaves, length of rhizome and weight of roots) and yield (rhizome weight per plant and per plot) of kacholam.
Control of root-knot nematode (Meloidogyne incognita Kofoid and White, Chitwood) infesting black pepper (Piper nigrum L.) by bacterial pathogens
(Department of Entomology, College of Horticulture, Vellanikkara, 1990) Sheela, M S; Venkitesan, T S
Eco-friendly management of root-knot and burrowing nematodes associated with kacholam (Kaempferia galanga Linn.)
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2001) Nisha, M S; Sheela, M S
Effect of organic amendments on plant parasitic nematodes and soil micro-organisms
(Department of Entomology, College of Agriculture, Vellayani, 1992) Ajith, K; Sheela, M S
Field experiments conducted to evaluate the effect of neem and eupatorium leaves at two levels on plant parasitic and non-parasitic nematodes and soil micro-organisms in the rootzone of bhindi and cowpea in rainy and summer seasons revealed that neem and eupatorium leaf treatments (300g/plant or 15 t/ha) were found effective in controlling Helicotylenchus spp., R. reniformis and M. incognita in the rootzone. Lower dose (150g/plant) of neem was found sufficient to suppress the Helicotylenchus spp. In the rootzone of bhindi. Effect of these treatments persisted up to 75 D A S in rainy season and 45 DAS in summer season. The effect of lower doses also persisted up to 30 DAS. The predatory and saprophytic nematode population build up in the rootzone was enhanced by higher dose of eupatorium. The effect on predatory fauna persisted up to 75 D A S in the rootzone of two crops. But in cowpea the effect on saprophytic fauna persisted only up to 60 D A S. The microbial populations (bacteria, fungi and actinomycetes) were increased in the rootzone of bhindi and cowpea in two seasons by the application of eupatorium leaf at higher dose where as neem leaf (higher dose) reduced the microbial population. Only the fungal population increased by the application of neem leaf at higher dose during rainy season. There was seasonal variation in population build up of fungi and maximum effect was seen in rainy season. The biometric characters (number of leaves, height of plant, root weight and shoot weight) and yield of bhindi and cowpea increased significantly by the higher dose of neem and eupatorium leaf. For increasing the height, lower dose of neem, and, for yield lower dose of neem and eupatorium also were found effective. The population of nematodes in the roots at the termination of experiment was significantly reduced by the higher dose of neem and eupatorium in bhindi while lower dose was found effective protecting cowpea roots.
Host parasite relationship and management of important nematodes associated with chethikoduveli, Plumbago rosea L
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2004) Santhosh Kumar, T; Sheela, M S
Integrated management of root- knot nematode, meloidogyn incognita(kofoid & white) chiywood in coleus, solenostemon rotundifolius (poir) morton
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2005) Nisha, M S; Sheela, M S
The root-knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood is a serious pest in coleus, Solenostemon rotundifolius Poir (Morton) causing damage to tubers both in field and storage. A detailed study was undertaken at College of Agriculture, Vellayani during 2002-2005 to evolve an integrated management strategy in coleus. Experiments were carried out to find out the extent of crop loss under micro plot and storage conditions, biochemical changes due to M. incognita infestation in tubers, to identify the varietal resistance and to select effective treatments in nursery (physical methods, bioagents and organic amendments) and main field (bioagents and organic amendments singly and in combination). Crop loss studies conducted under microplot condition indicated that there was significant reduction in biometric characters at monthly intervals from lowest inoculum level of 100 J2 onwards. The yield attributing characters also showed significant reduction at 100 J2 level (15.77 to 19.13 per cent). In the case of nematode population, there was progressive increase in recovery as the initial inoculum level increased from 100 to 5000 J¬¬2. Crop loss studies under storage condition revealed that tubers obtained from 5000 and 1000 J2 inoculated plants started rotting and get deteriorated at 15 and 45 days after storage respectively. The stored tubers from 500 J¬2, 100 J2 and uninoculated plants exhibited a weight loss of 96.50, 86.50 and 12.50 per cent respectively at three months after storage. Germination percentage of tubers collected from 100 and 500 J2 inoculated plants showed 42.37 and 7.47 reduction respectively over the uninoculated at three months after storage. The vigour of the plants in terms of biometric characters also reduced significantly at the lowest inoculum level of 100 J2. The biochemical changes of tubers collected from plants inoculated with different levels of M. incognita revealed significant reduction in starch, sugar and crude fibre content. The percentage reduction being 6.32 to 33.33, 8.06 to 17.47 and 18.99 to 62.03 respectively as the population of nematodes increased from 100 to 5000 J2. However, there was slight increase in protein content from 12.94 to 14.42 per cent. Results on the resistance of coleus varieties/lines/accessions against M. incognita, established that variety Sree Dhara performed better in reducing the multiplication of nematodes in soil, root and tuber and production of root-knots, females, egg masses and eggs per egg mass. However in the case of total, marketable and edible portion weight of tubers, the performance of variety Sree Dhara and Nidhi was statistically on par. Based on the statistical superiority of the variety Sree Dhara to resist nematode infestation and numerically higher yield than Nidhi, Sree Dhara was selected as the resistant variety and included as a component in ensuing integrated nematode management study in coleus. The evaluation of various treatments in the nursery revealed that soil solarization using 150 guage LDPE film for 15 days or application of bioagent viz., Paecilomyces lilacinus or Bacillus macerans @ 30 g m-2 significantly reduced the number of larvae, root-knots and egg masses in root (65.74 to 90.75 per cent reduction over the untreated). The reduction in M. incognita population contributed significant improvement in biometric characters which in turn resulted healthy vigorous cuttings of S. rotundifolius for transplantation. Thus soil solarization and application of either P. lilacinus or B. macerans were selected as nursery treatments for further investigations. Among the main field treatments, application of P. lilacinus (15 g m-2) in combination with either neem cake (100 g m-2) or B. macerans (15 g m-2) significantly reduced M. incognita population and improved the biometric characters, yield and quality parameters of S. rotundifolius. The treatment combinations, P. lilacinus + neem cake and P. lilacinus + B. macerans showed 81.42 and 71.58 per cent increase respectively in total weight of tubers when compared to untreated. In integrated management, the selected treatments in the nursery and mainfield were evaluated using the resistant variety Sree Dhara. Based on the overall performance in reduction of nematode population (soil and root), the improvement of biometric characters and yield of coleus tubers, integration of soil solarization in nursery for 15 days with 150 guage LDPE film and main field application of P. lilacinus (15 g m-2) in combination with either neem cake (100 g m-2) or B. macerans (15 g m-2) were the best treatments for recommendation in the integrated nematode management strategy in S. rotundifolius. This strategy protected the crop against M. incognita and improved the per ha yield to a tune of 64.33 to 66.18 per cent. In addition to this, by reducing the nematode population in root (97.89 to 99.73 per cent), the quality parameters of tubers like starch, sugar and crude fibre content were also maintained.
New records of plant parasitic nematodes from Kerala
(Kerala Agricultural University, 1981) Venkitesan, T S; Charles, J S; Sheela, M S
Potential of entomopathogenic nematodes for the management of weevil pests of banana (musa SP)
(Department of Agricultural Entomology, College of Agriculture, Vellayani, 2007) Remya, K R; Sheela, M S
A study was taken up, to isolate native entomopathogenic nematodes from banana rhizosphere, to standardize artificial media for the wax moth Galleria mellonella L., the trap insect of EPN, to identify cheap medium for the mass production of native EPN, to establish the potential of native isolates of EPN in comparison with the standard cultures by screening and to assess the potential of native isolates for the management of two major weevil pests of banana viz. , pseudostem weevil Odoiporus longicollis Oliv. and rhizome weevil Cosmopolites sordidus Ger. in the laboratory of Department of Agricultural Entomology, College of Agriculture, Vellayani during 2005-06. Native isolates of EPN were collected from banana rhizosphere in six blocks of the Instructional Farm, Vellayani covering an area of 75 ha. Out of the hundred samples processed, ten native isolates were obtained. Based on the mortality of grubs of pseudostem weevil in the laboratory, the native isolates N1 and N2 were selected for further studies. The G. mellonella larvae were fed with standard medium along with cheap media viz., M1, M2, M3 and M4. The result revealed that among the cheap media, maximum survival of larvae was recorded in M1 medium. The cost of preparation of standard medium used for the rearing was high as compared to other three media. The percentage reduction of cost of ingredients of M1, M2 and M3 media from the standard medium was 21.29, 34.87 and 21.67 respectively. Among the three media, minimum reduction in cost of ingredient was computed for M2 medium. But considering the number of larvae survived and mass multiplication rate M1 medium was promising. For mass multiplication of native EPN, the rate of multiplication of infective juveniles was assessed in G. mellonella reared in different cheap media along with standard medium. The result showed that all the EPN (H. indica, S. glaseri, N1 and N2) reared in standard medium recorded maximum emergence of infective juveniles. The studies on the rate of multiplication of native isolates along with standards revealed that initial inoculum of 10 infective juveniles per G. mellonella larva recorded maximum emergence of infective juveniles of all EPN except N2. But the native isolate N2 required an initial inoculum level of 25 IJ per G. mellonella larva for maximum emergence of infective juveniles of EPN. The results of the study revealed that maximum emergence of EPN including native isolates were recorded at 20 days after inoculation rather than 15, 10 and 7 DAI. In order to establish the potential of native isolates on the mortality of grubs and adults of pseudostem and rhizome weevil, trials were conducted in vitro condition and using infested pseudostem and banana rhizome in the laboratory condition. Maximum mortality of grubs and adults of the pseudostem and rhizome weevils were recorded at 72 hrs after treatment. Under in vitro conditions the inoculum required for getting maximum mortality of grubs of pseudostem weevil was 100 IJ per grub, while it was 200 IJ per grub in rhizome weevil. In the case of adult weevils, the inoculum level required to get maximum mortality was 200 IJ per adult in both the cases. But inside the pseudostem and banana rhizome both the grubs of pseudostem and rhizome weevils recorded maximum mortality with 100 IJ per grub. From this investigation it was evident that native EPN strains are available in different agro ecosystems and are more virulent than the standard ones. The rearing media for trap insect, G. mellonella was modified with cheap ingredients and there by reducing the cost of production to 21.29 per cent with out affecting the nutritional status and survival of different instars. Comparative efficacy of native isolates (N1 and N2) and standards were worked out for the management of grubs and adults of weevil pests of banana. An inoculum level of 100 IJ per insect recorded a mortality of above 80 per cent in vitro condition in rhizome and pseudostem weevils but it was reduced to 52 to 56 per cent inside the rhizome and pseudostem. Thus from these studies, mortality of grubs and adults of the weevils inside the banana pseudostem and rhizome required a minimum inoculum level of 200 IJ per insect.