Two & a Bud

Eocanthecona furcellata (Wolff) (Hemiptera: Pentatomidae): A potential biocontrol agent of the major tea pest Hyposidra talaca (Walker) (Lepidoptera: Geometridae)

Suman Sarkar — 2023-09-20

The present study was conducted to generate information on the fitness of the potential predator Eocanthecona furcellata in order to develop the biological control strategy for the destructive tea pest Hyposidra talaca (Walker) (Lepidoptera: Geometridae). This predatory bug showed high reproduction, growth, and survival fitness when reared on an alternative host Corcyra cephalonica under laboratory conditions. The predatory potential of this pentatomid bug revealed an average of 7.6±0.47 larvae per day by the female predator. However, all the nymphal stages showed a significant increase in predation with the advancement of developmental stages. All the life stages of the predator when exposed to commonly used recommended pesticides in the tea ecosystem viz., Quinalphos 25 EC, Thiamethoxam 25WG, Emamectin benzoate 5% SG, and Flubendiamide 20 WG at the recommended doses, showed superior fitness in the treatment with Emamectin benzoate and Flubendiamade when compared to other two pesticides. Therefore, this study shows that E. furcellata could be utilized effectively by mass rearing and augmentative field release for the management of H. talaca.

Keywords: tea, predator, IPM.

Residues of Spirotetramat and its metabolite in Tea and Soil

B. Kanrar — 2023-09-20

Spirotetramat is a systemic, ambimobile, keto-enol group of insecticide developed by Bayer Crop Science against sucking insects, eg. aphids, mites, thrips and white flies. To generate data on residues in tea and soil after application of Movento (Spirotetramat 150 OD) supervised field trials were carried out at 4 locations viz. Borbhetta Tea Estate, North Bank, Dikom & Nagrakata, West Bengal during the year 2017. The formulation was sprayed twice consecutively in 7 days interval @ 90 g a.i./ha (X) and 180 g a.i./ha (2X). Sampling was done at intervals of 0 (2 hr), 1, 3, 5, 7, 10 and 14 DAS. About 2 kg of tea shoots plucked on 0, 7, and 14 days after treatment was processed to CTC black tea and green tea at Tocklai. Samples of tea shoots, black tea, green tea and tea brew were analyzed for residues of spirotetramat and spirotetramat enol by a modified QUECHERS based LC-MS/MS method. The average recoveries of spirotetramat and its metabolite were found to be 76% to 120%. The half-life was found to be 2.53 & 2.32 days for single and double the recommended dose, respectively. The residues in black tea sample corresponding to 7day PHI were 0.21 to 2.71 mg/kg while the same in green tea was 0.30 to 2.00 mg/kg at recommended (X) dose. No residues were found in 14 D soil sample. Transfer rate of residues to tea brew were also very much limited.

A preliminary study on the variation in fluoride content in tea shoots in relation to plucking

Piw Das — 2023-09-20

Fluoride (F-) is an essential micronutrient for humans but a narrow margin exists between the requirement and toxicity of F- in the human body. Adequate intake (AI) of F- collectively from all sources for adult male, female and children are 4 mg/day, 3 mg/day and 1-2 mg/day, respectively. The tea plant can selectively absorb F- from soil accumulating them in shoots in a complex form which increases with the increasing age of the tea leaves. Moreover, acidic soil is conducive to the uptake of increased amounts of fluorides. Major portions of the total fluorides stored in tea plant are in the leaves, the concentration ranging from 2.1 to 1175 mg/kg and 26-808 mg/kg in medium and young aged plantations, respectively. The aim of the present work was to determine the total F- in green tea shoots (2 leaves & bud, 3 leaves & bud, 4 leaves & bud, 5 leaves & bud) and made tea. Total fluoride in green tea shoots was found to be 78, 123, 133 and 145 mg/kg for 2 leaves & bud, 3 leaves & bud, 4 leaves & bud, 5 leaves & bud respectively while the same in brew was 0.89, 1.02, 1.40, and 2.15 mg-L-1 respectively. The release of fluoride into brew ranged between 41-74%. The results of this preliminary work thus indicated that plucking of coarse green leaf may have a detrimental role on the occurrence of fluoride in made tea.

Keywords: Green tea leaves, Fluoride, micronutrient

Screening of microbial strains for antagonist property against fusarium species

M. Madhab — 2023-09-20

Tea (Camellia sinensis) being a perennial and monoculture crop is prone to many pests and diseases. Tea plant is mostly attacked by many foliar, stem and root disease. Among many tea disease like black rot, red rust, blister blight etc, Fusarium die back disease is becoming a great concern in the recent time. It is further observed from the research study that there exist a great species diversification among the pathogenic stain of Fusarium die back disease i.e Fusarium solani. Thus an attempt was made for the first time in Assam to make a study of the Fusarium solani species complex and Fusarium species variations in tea. From the disease survey report it was found that recently Upper Assam and South bank of the Brahmaputra valley is threatened with the spread of the Fusarium die back disease caused by Fusarium species. Using this strategy, we isolated and identified morphologically 9 numbers of fungal isolates, among which 4 dominant strains coded as FDB26, FDNKY, FDHK, FDPT, FDHPJ were separated on the basis of their difference in the morphological and microscopic observation and were further used for antagonistic screening trial. Three microbial culture collected from preserved microbial depository of TTRI were used for the antagonistic study which are namely Trichoderma viride (TV), Pseudomonas corrugata (PDS-01), Bacillus subtilis (BST). Thus from the antagonistic screening test it was observed that TV, PDS-01 and BST showed highest antagonism against FDPT. PDS-01 and TV exhibited strong activities against isolates of FDB26. Thus in conclusion, we can say that Pseudomonas corrugata (PDS-01)showed highest antagonistic potentiality against all the four dominant Fusarium strains and could be used as an efficient Bioinoculant and Biocontrol agent in Fusarium die back disease infested areas.

Evaluation of indigenous entomopathogenic nematodes from tea soil of Assam as potential bio-control agents against Termites and Cockchafer grub in tea

A. Rahman — 2023-09-21

This study aimed to isolate native entomopathogenic nematodes (EPN) in the tea growing areas of Assam and to determine their potential for control of Termite and Cockchafer grub. Soil samples were collected from three tea estates of jorhat, Assam for EPN isolation.A total of 30 soil samples were tested for the study. Larva of meal moth, Corcyra cephalonica was used as insect bait. Out of 30 samples 9 were found to be positive for EPNs. The infected host larvae were separated for extraction using “white trap method”. All the isolates were evaluated to ascertain their pathogenicity against Termite and cockchafer grub. From the experiment the isolated strain @ 50IJ, 75IJ and 100 IJ was found to be highly pathogenic to Termite and cockchafer grub, which recorded 94-100% mortality in termite and 100% in all concentrations against cockchafer grub. After infection to prove the cause of mortality EPN could be recovered from the termite and cockchafer cadavers.

Keywords: Corcyra cephalonica, EPN, pathogenicity, cadavers

Strategy for sustainable tea cultivation using microbial consortium of biofertilizers : A case study

A.J. Tanti — 2023-09-21

Exploitation and utilization of microbial bio fertilizers for reducing dependence on synthetic chemicals is a good strategy for tea planters, as input of bio fertilizers with less use of inorganic fertilizers can help in the improvement of soil health and reduce environmental contamination as well. The present investigation deals with the exploitation and utilization of certain native beneficial soil microbes [Azotobacter sp. (AZR), Azospirillum sp. (AZM), Bacillus sp. (BST) and their consortium] in tea soil as biofertilizers, for optimal plant nutrients starting from the planting pit in young tea management (YTM). The YTD treatments were divided into – (I) Full Dose (FD) and (II) Half Dose (HD). Among all the treatments, crop gain was recorded maximum at Azotobacter sp. (HD) followed by Azospirillum sp. (HD) indicating microbial potentiality with lesser chemical input. The other plant growth parameters viz., plant biomass, stem girth and the number of branches were also found to increase significantly in the microbial treated plots. At HD of NPK, the performance of Azotobacter sp. was observed to be better, with an increase of 10.7% gain over control in stem girth compared to Azospirillum sp. (8.8% increase), while per cent gain in biomass was maximum with Azospirillum sp. (up to 55.5%). The plants subjected to microbial treatments showed increased branching over control. The findings of the experiment thus, ensures the potential of using microbial biocides in combination with inorganic fertilizers, as an eco-friendly and more reliable component to achieve sustainable tea cultivation and in the long run it would serve as an asset for renewable source of energy and nutrients.

Keywords: Beneficial microbes, inorganic fertilizer, microbial biocide, plant biomass, sustainable tea cultivation, young tea management.

Impact of Biofertilizer on Tea Productivity and Soil Properties

H. Malakar — 2023-09-21

A study was conducted to determine the impact of consortium of biofertilizer containing nitrogen, phosphate, potash & zinc (Bio NPK) on tea production and soil quality. The experiment included five different combinations of treatments, each with three replications, on three types of pruned tea. The results showed that the crop yield significantly increased when bio-fertilizer was combined with the recommended dose of fertilizer (RDF). The yield increased by 3.4 to 4.7% when 100% of RDF with bio-fertilizer was applied, regardless of pruning type. Additionally, the yield increased by 1.9 to 3.5% when 75% of RDF with bio-fertilizer was applied over 100% of RDF. After the experiment, the analyzed soil data showed that the available nitrogen, phosphate and potassium content in the soil was significantly higher in the treatments where 100% and 75% of RDF with bio-fertilizer was applied compared to only 100% of RDF treatment. The use of biofertilizers synchronized with inorganic fertilizers application increased the concentration of nutrients in the plants. Moreover, the microbiological analysis revealed that the microbial populations increased in treatments treated with biofertilizer compared to only inorganic fertilizers. Therefore, the experimental results concluded that using 75% of RDF with biofertilizer could effectively maintain sustainable tea production without compromising soil health.

Keywords: Bio-fertilizer, Soil, Tea Productivity

Significance of Microbes and their role in pest management in tea ecosystem: A mini-review

A. Babu — 2023-09-21

Tea plantations are subjected to damage by several insect pests and mites resulting in significant crop loss every year. Although efficient control has been achieved by the use of recommended synthetic pesticides over many years, they contribute to several ill effects such as the resurgence of pests, the development of insect pest resistance unwanted residues in the made tea. This has led the planting community to look for safe alternative methods to tackle pests and diseases on tea. Microbials play vital in combating pest menace in many agroecosystems including tea. Emphasis on the use of natural enemies such as entomopathogens and antagonists for pest/disease control has expanded the range of control possibilities. The incorporation of eco-friendly alternatives to existing agricultural pesticides that are employed to manage insect pests and improve sustainability has been popularized in recent years. This review summarizes current knowledge on entomopathogenic fungi, nematodes, viruses, bacteria, etc. as it relates to their possible utilization in biological pest management in tea.

Keywords: Entomopathogenic fungi, Bacteria, Viruses, Nematodes, Pest management

Chemical Compositions, Health Benefits and Product Diversification of Tea:

P.P. Sarmah — 2023-09-21

Tea is mostly considered as a processed product from the fresh tender leaves of Camellia sinensis through different processing techniques. Based on the processing technique tea is named green tea, black tea, oolong tea, etc. The biochemical components in tea leaves consist of mainly catechin, phenolic acids, purine alkaloids, amino acids, saponins, tannins, flavonols, and their glycosides in many forms. Each type of tea has its own set of chemical compositions with a distinct flavour. All these bioactives cause significant changes in their biological activities both in vitro and in vivo and possess numerous health benefits. With the growing production of raw materials in India and with the change in trends of taste and use, price realization is going down and without the development of newer products like ready-to-drink tea, nutraceuticals from tea bioactive, etc, sustainability will be a challenge. In the present review, the chemical composition and health benefits of tea and new kind of value-added products based on tea are also discussed briefly.

Keywords: Camellia sinensis, tea, catechin, theaflavins, diversified product

Ambient humidification of CTC and CFM room: Its effect on quality of tea

S. Sanyal — 2023-09-21

During black tea processing, visible changes take place in the oxidation stage. Regulated andcontrolled environment is crucial to optimize the process. The control parameters for oxidation process are, availability of oxygen, temperature, humidity and time. Humidified air is supplied into the fermenting systems – Floor, Gumla or CFM – to ensure an oxygen rich humid environment. Elevated humidity restricts depletion of moisture from the CTC processed leaf. A hygrometric difference of around 1-2 0C is recommended for the above. This in turn also helps in reducing the room temperature closer to the recommended level of 27-30 0C. In most commercial tea factories, spot humidifiers and overhead duct humidification system are used. But they are being rapidly replaced by more efficient misting or fogging systems which enable ambient humidification with micro fine droplets. This paper presents the results of the trials conducted with a High Pressure Fogging System which was installed at the Model Tea Factory, TTRI, Jorhat. The effect of this technology was extensively assessed/reviewed in fermented dhool, as well as on made tea over a period of two years. Results show that it was possible to achieve a humidity of 91.8% to 95.9% inside the fermenting room while the prevailing ambient humidity levels recorded varied from 71.9% to 74.40%. The appearance of the treated samples on fermentation bed was very bright and the made teas were preferred by the tasters. However, the above observations were more pronounced on days of low ambient humidity,in which case the tasters’ scores on made tea were significantly higher with respect to brightness, briskness, strength and quality, compared to the control samples.

Keywords: Misting system, Fogging system, Cooling systems, Humidifiers, Polyphenols, Theaflavins, Thearubigins.