TEA (Camellia sinensis)
Tea grows best in areas with a maximum temperature of 16-32 ºC and a well distributed rainfall of about 150 cm per annum. Relative humidity should be around 80% most of the time and should never be less than 40%. The area should not be prone to frost. The soil should be acidic (around pH 5.0) having good drainage facility.
Varieties
Clones: UPASI-2, UPASI-8, UPASI-9, UPASI-17, TRI-2025, TRF-1
Seedlings: BSS-1, BSS-2
Propagation
The seed viability extends up to 6 months. Before sowing, seeds are put in water and only the sinkers will be used and floaters rejected. Seeds germinate in 4-6 weeks and the cracked seeds are transplanted in polythene sleeves. The plants will be ready for planting in the main field in 9 months.
Manuring of nursery plants
Composition of tea nursery mixture is as follows:
Ammonium phosphate (20:20) 60 parts
Potassium sulphate 24 parts
(or) Muriate of potash 20 parts
Magnesium sulphate 16 parts
Stock solution
Dissolve 30 g of the mixture in 10 litres of water. This can be sprayed over 2 m2 (450 plants) at weekly interval.
Field preparation
In the case of new planting, in order to avoid the incidence of root diseases, after felling the trees, remove the root system to the extent possible. Clear the jungle growth but do not burn, the ash being alkaline will increase the pH.
In the case of replanting, remove old Grevillea (silver oak) after ring barking, leaving the young ones in the field. Level the land into an even slope to facilitate easy cultural operations and proper drainage.
Style of planting
Up and down: 1.2 x 1.2 m (6800 plants/ha)
Contour planting, single hedge: 1.2 x 0.75 m (10,800 plants/ha)
Contour planting, double hedge: 1.35 x 0.75 x 0.75 m (13200 plants/ha)
The double hedge planting will accommodate more number of plants per unit area. Early high yield, better soil conservation, less weed growth, efficient cultural practices and better supervision are other advantages of double hedge planting.
Pitting
Pits of size 30 x 45 cm are taken. Keep the top and bottom soil separately. In clayey soil and drought-prone areas, deeper pits (60 cm) or trench planting will be advantageous.
Planting seasons
Southwest monsoon areas: June-July
Northeast monsoon areas: September-October
Planting
If the soil pH is more than 5.5, apply 100 g of powdered aluminium sulphate per pit and thoroughly mix with soil. Select seedlings of 12 months old. After planting the seedling, compact the soil surrounding the plant and apply mulch at the rate of 25 t/ha. While mulching care should be taken to keep the mulch material away from the collar region of the plant by putting a peg above the plant on the slope. Wherever mulch material is a problem, intercrop or cover crop could be raised.
Manuring
Manuring of young tea commences 2 months after planting. The ratio and source of nutrients vary according to soil reaction (pH).
The rate of fertilizer application for mature tea varies with yield and soil test values while the N:K2O ratio varies with the stage of pruning.
Method of application
Apply the recommended quantity of mixtures along the drip circle of plants. In the semi-circular furrow taken above the plant on the slope, using a Kokra-eyebrow method, apply the fertilizers when there is adequate soil moisture and when the fields are free from weeds. Punch holes of 15-22 cm depth in the soil on either side of the plants and place the rock phosphate.
Training of young tea
Proper training of young tea is essential to encourage good spread of the bushes, proper development of frames and high density of plucking points.
Centering
Cut the leader stem of the plants with secateur to arrest the apical dominance and to induce the secondary branches. Cut as low as possible leaving 8-10 mature leaves below the cut. Ensure proper recovery. Centering should be done 4-6 months after planting during humid weather when there is adequate moisture in the soil.
Tipping
First plucking of the periodic shoot is done after centering / pruning. Two-tier tipping ensures proper spread. First tipping at 35 cm height will induce the tertiaries. Second tipping at 50 cm height will increase the density of plucking points. Tipping should be done at green, semi-hardwood branches. Tipping should be done in shoots having 3-4 leaves and a bud.
Plucking
Mother leaf / step-up plucking is practiced during lean seasons. Level plucking is done during high cropping months. This is essential for better frame development.
Shade management
The best permanent shade tree for tea plantation in South India is silver oak (Grevillea robusta).
Planting of silver oak
The silver oak can be propagated through seeds. The seeds should be sown within 6 months after collection. Seed should be sown in raised beds of 1 m width and of convenient length using sandy loam soil with a pH around 6.0. Seed should be covered with thin layer of sand / ash. Germination takes place in 2-3 weeks. Use 6-9 month old seedlings for planting. Plant along tea rows at a spacing of 6 x 6 m (275 plants/ha). Apply a mixture of 100 g rock phosphate and 400 g dolomite per pit and thoroughly mix with soil prior to planting. Apply NK mixture @ 100 g/tree twice in a year; rock phosphate at 250 g/tree and borated lime 1.1 kg (1 kg dolomite + 100 g boric acid) during alternate years.
Shade regulation
Tea requires only sparse shade. So retain optimum stand of shade based on the growth of the tree, altitude of the garden and aspect of the field (south and west slopes require more shade). Thin out shade initially to 12 x 6 m after 8-10 years of planting and if required further thinning may be done to 12 x 12 m at later stages (12 years from planting). Always thin out shade prior to pruning.
Pollarding
Cutting the main stem with the objective of developing lateral branches is pollarding. Commence pollarding when the trees attain a girth of around 50 cm at elbow level. Pollarding depends on altitude (8 m height for higher altitude, 9 m for low elevation). Leave one branch in each direction and 3 to 4 tiers of branches, below the pollarding height.
Annual lopping
Cutting the erect growing branches on the laterals is lopping, which should be done before the onset of monsoon and lop only the erect branches and retain the laterals.
Shade removal
Useful age of Grevillea is 40-60 years. Remove old trees after establishing new shade.
Temporary shade
For frost prone areas: Acacia mearnsii
For mid elevations: Indigofera teysmanii
For higher altitude: Sesbania cinerescens,
Crotalaria agathiflora and Acacia elata
Planting at 3 x 3 m spacing is adopted. Temporary shade should be removed after establishment of Grevilliea after 3 years.
Plucking
Ten commandments for plucking
1. Harvest two to three leaves and a bud and / or single and two-leaf banjis.
2. Pluck the mother leaf during January-March.
3. Pluck the new level during rest of the month.
4. Pluck at 7-10 days interval during high cropping months.
5. Pluck at 12-15 days interval during low cropping months.
6. Removal of banjis and breaking-back should be a part of plucking operation.
7. Do not pluck below the level.
8. Leave immature shoots.
9. Shear-harvest during rush periods.
10. Cut lanes in older fields.
Post-pruning care
Apply copper oxychloride or sulphur + linseed oil (1:1) to large cut-ends after rejuvenation and hard pruning.
Plant protection
Nematodes (Meloidogyne spp.)
These microscopic worms infest roots, which develop to knots or galls. Affected roots become defunct and devoid of lateral roots. Plants exhibit chlorosis and stunted growth.
Control
Nursery
Heat treatment: Spread soil sand mixture (5 cm thick) on a G.I. sheet. Heat it from below. Sprinkle water periodically. Mix the soil thoroughly by turning. Optimum temperature is 60-65ºC. Soil should not be too hot to hold in the hand. Over heating of soil will lead to manganese toxicity.
Chemical treatment
Mix carbofuran 3G (700 g/m3) thoroughly with soil and make it into a bed of 1 m width, 1 cm height and of convenient length. Give profuse watering at 3-5 days interval. Completely mix the soil before filling
Mature tea
Neem cake 2 kg per bush is recommended.
White / cockchafer grubs (Holotrichia sp.)
The creamy white grub eats away the roots. The main symptoms are ring barking of stem, chlorosis and defoliation. The pest is a serious problem in areas where un-decomposed farmyard manure is used.
Control
Nursery: Heat treatment of soil and use of granular insecticides is practised.
New clearing: Drench endosulfan (1:500 dilution)
(1) At the time of planting: 500 ml per pit
(2) Post-planting treatment: Loosen the soil around the bush and pour one litre per bush.
Root mealy bug (Dysmicoccus sp.)
The pest is a problem in the nursery. It sucks sap from the callusing region, mother leaf petiole and axillary buds. This arrests root development; leads to mother-leaf fall and finally death of plant.
It can be controlled by spraying and soil drenching with chlorpyrifos or quinalphos 0.2%
Stem borers
Red coffee borer (Zeuzera coffeae)
Mostly seen in new clearings as batches. Young stems are bored and larvae tunnel downward, make holes at intervals to eject excreta and wood particles. Frass and excreta are seen around plants. Alternate host of the pest is coffee and cocoa.
Large hepialid borer (Sahyadrassus malabaricus)
This is a polyphagous pest attacking teak, eucalyptus and lantana. Thick branches (3 cm diameter) are preferred by the pest. Callus tissue and wood form food for larvae. Entrance holes are covered with frassy mat formed with chewed wood and silk.
Control
Cut the affected stem and pour quinalphos using ink filler. The holes are plugged with clay paste.
Mites
Several species of mites attack tea plants. They are dry weather pests mostly attacking mature foliage except pink and yellow mites.
Control
If infestation is more, chemicals like dicofol, quinalphos and monocrotophos will be effective.
Thrips (Scirtothrips bispinosus)
This is a major pest in all tea growing countries. Feeding causes lacerations of tissue and appears as streaks. Leaf surface becomes uneven, curled and matty. Feeding marks in bud appear as parallel lines on either side of mid-rib when leaf unfolds. Leaf margins turn yellow.
Control
Endosulfan, phosalone, monocrotophos, quinalphos and dimethoate can be used for the pest control.
Tea mosquito bug (Helopeltis theivora)
Adults and nymphs suck the sap from buds, young leaves and tender stems. Due to intensive feeding, leaves curl up, badly deform and shoots dry up. Chemical control involves spraying quinalphos + dichlorvos at spray intervals depending on the intensity of incidence
Root diseases
Black root disease (Rosellinia arcuata)
Common in areas, which were previously under jungles. The common symptoms are wilting, chlorosis, drying without defoliation and death of bush.
Control
Remove surface mulches around 10 metres. Drench soil with mancozeb 30 g per 10 litres of water. Follow phytosanitary measures. Biocontrol agents Trichoderma or Gliocladium (200 g per pit) may be incorporated at the time of planting.
Other root diseases are red root disease (Poria hypolateritia), brown root disease (Fomes noxius), root splitting disease (Armillaria mellea) and xylaria root disease (Xylaria sp.). Phytosanitary measures, use of biocontrol agents and chemical control (drench soil with tridemorph or hexaconazole 0.5%) are recommended.
Stem diseases
Collar canker (Phomopsis theae)
Seen mostly on young tea. The pathogen invades stem mostly through open wound. The predisposing factors for the disease are deep planting, planting in gravelly soils, mulching closer to collar, wounds caused by weeding implements, fertilizer application close to collar, pegging, low moisture status in bark and surface watering during dry weather. The main symptoms are chlorosis, cessation of growth, profuse flowering and canker on stem.
Control
Remove affected portion by pruning the healthy wood and apply copper fungicide to cut ends.
Other stem diseases are branch canker (Macrophoma theicola), wood rot (Hypoxylon serpens) and dieback (Leptothyrium theae).
Leaf disease
Blister blight (Exobasidium vexans)
The fungus affects only tender leaves and stems (pluckable shoots). Translucent spots occur in three to ten days and well developed lesions are seen in two weeks. Lesions are sunken on the upper surface and convex at lower surface. Affected leaves are distorted and irregularly rolled. Stem infection leads to goose-neck shape, dieback and snapping at the point of infection.
Control
Copper oxychloride 350 g + plantomycin 70 g per ha at 3 to 4 days interval can control the disease.
No comments:
Post a Comment