Production technology of Rubber (Hevea brasiliensis)

Rubber - Climate and soil requirements - varieties- propagation - nursery management - planting and planting systems - cropping systems- after care- training and pruning - water, nutrient and weed management - shade management - intercropping - mulching - cover cropping - special horticultural practices - maturity indices, harvest and yield - pests and diseases - processing

1. Botanical Name : Heavea brasiliensis
Family : Euphorbiaceae
Origin : South America
Chromosome No. : 2n = 36
Production technology of Rubber
Dr. M. Kumaresan (Hort.)
Department of Horticulture
Vels Institute of Science, Technology &
Advanced Studies (VISTAS)
Pallavaram, Chennai, Tamil Nadu -600117

2. •Rubber is also called India rubber, latex, Amazonian rubber, caucho, or caoutchouc, as
initially produced, consists of polymers of the organic compound isoprene
•Thailand, Malaysia, Indonesia, and Cambodia are four of the leading rubber producers
•Heavea brasiliensis species produces about 99% of worlds natural rubber, its yield and
quality of latex is superior over other spices
•It is among the largest families of plants, comprising over 230 genera and 5,700 species.
•Latex is a sticky, milky and white colloid drawn off by making incisions in the bark and
collecting the fluid in vessels in a process called "tapping".
•Natural rubber is used extensively in many applications and products, either alone or in
combination with other materials. In most of its useful forms, it has a large stretch ratio
and high resilience and also is buoyant and water-proof
Introduction

3. •1770 - Joseph Priestly discovered that the material would rub out paper
marks, hence the name India rubber
•1823 - Mackintosh manufactures waterproof raincoats by coating fabric
with rubber dissolved in naphtha
•1839 - Goodyear discovered vulcanization, when rubber was heated with
sulfur, rubber retained physical properties from 0 to 100°C. This led to
rubber boom
•1898 - Dunlop rediscovers pneumatic tires (Motor cars invented in 1885)
History

4. •70% of total rubber consumption is in the manufacture of tyres and tubes.
•About 6% of worlds rubber is used for manufacture of foot wear, soles and heels
and 4% for wire and cable insulation.
•Other uses such as rubberized fabrics, shock absorbers, washers and gaskets,
conveyor belting , sports goods, vulcanized a hard high sulphurized rubber is used
in electrical and radio engineering.
•Rubber powder with bitumen is used for road surfacing.
Use of rubber

5. •Total area in the world is 8.5 million ha Asian countries account for 93% of area
under rubber
•Indonesia is the main rubber producing country - 3,29,000 ha followed by Thailand
•India ranks 5
th
& 4
th
in area (566555ha) & production (707100t)
•India ranks 1
st
in productivity (1592kg/ha)
•Kerala has maximum area (4,75, 039 ha) followed by Tripura, karnataka and Tamil
Nadu
•Kerala - 81% of the world production is contributed by the major producers
•Thailand is the largest producer (2873100t) contributing 36% in the world followed
by Indonesia
•Total consumption in the world was 79,10,000t
•China followed by USA & Japan are the major consumer
Area and production

6. Importance
•Rubber is an important industrial raw material
•Used to fabricate very large number of articles useful for mankind
•Latex from the bark is the economic part in rubber
•Seed oil, seed cake and rubber tree honey are the important by-products of rubber
•Seed oil is pale yellow non edible liquid used for manufacturing soaps and paints
•Seedcake is rich in protein & used as animal & poultry feed
•Organized commercial exploitation of honey from rubber plantation was promoted
by KVIC (Khadi and Village Industries Commission)

7. Climate and soil
Soil
•Rubber is a hardy plant it can be grown on wide range of soils
•However, well drained sandy loam, forest loam and laterate soil with good water
holding capacity are suitable for its cultivation
•A soil pH of 5.5-6.5 is ideal
•Rubber normally cultivated in hilly and sloppy area
•Thus before cultivation adequate soil conservation has to be adopted

8. Climate
•Rubber is a tropical plant
•It requires warm and humid weather
•The optimum elevation for growing rubber is 500m from MSL
•A rainfall of 2000 mm are more evenly distributed without any marked dry season
and with 125-150 rainy days per annum is necessary for best growth of rubber
•A maximum temperature of about 29-34
0
C, minimum temperature of about 20
0
C
•Relative humidity of 80% and bright sunshine of about 2000 hours at the rate 6
hour per day in all the month are considered suitable for cultivation of rubber.
Climate and soil

9. Classification of rubber clones
•Rubber clones are broadly classified into three categories based on the methods
adopted for the development of mother trees
•Primary clones: When mother trees are selected from existing seedling
populations of unknown parentage and are multiplied vegetatively. Eg: Tjir –
1(Tjirandji –1 of Indonesia), G.T-1 (Godng Tapen of Indonesi) , G.I –1( Glenshiel-1
of Malaysia) and PB-86.
•Secondary clones: When the mother trees are evolved by cross pollination (hand
pollination) between two primary clones and are then multiplied vegetatively, they
are known as secondary clones. Eg: 1) RRIM – 600 = TJIR –1 x PB – 86 and 2)
PRIM - 628 = TJIR –1 x PRIM – 527
•Tertiary clones : Are produced by controlled pollination of two existing clones, but
they differ from secondary clones in that at least one of parents or both the parents
are of secondary clones. Eg: RRIM – 703 = RRIM – 600 x RRIM –500.

10. Polyclonal seedlings in rubber
•All desirable characters viz., high latex content, drought resistance etc., may not be
available in a single clone.
•Hence, it may not be wise to adopt a single clone for cultivation in large areas,
because if disease or pest epidemic occurs the entire plantation may be wiped out.
•Therefore to get the benefits of mixed clones in a population, poly clonal seed
gardens are being established by blending different clones.
•The hybrid RRII –105, is the highest yielding in the world.
•It has become very popular, occupying 80 per cent of the area under rubber.
•Its average yield is 2.400 kg /ha/year.

11. Polyclonal seedlings in rubber
•Superior clones numbering 3 to 6 are planted in an isolated area and allowed for
natural open pollination.
•For prevention of pollen contamination from rubber trees of neighboring area an
isolation belt of 100 m width is provided all around the seed plantation.
•Polyclonal seed families generally give rise to seedlings of good vigour and growth.
•In olden days monoclonal seeds of single selected mother clones such as Tjir –1,
not contaminated by crossing with seedling rubber or undesirable male parent
clones had been extensively used as improved plant materials.
•Poly clonal seeds are easier to establish and maintain when compared to buddings.
•The trunk of the seedlings are much larger than those of budded trees.

12. Clones / varieties
•Earlier plantations were established through highly cross pollinated unselected
heterogeneous seeds.
•They are poor yielders
• Later high yielding clones were released for commercial cultivation in India, by
‘Rubber Board of India’ and occupied more than 85% of area under rubber
•RBI approved 3 categories of clones for cultivation in India
•1.RRII 105, PB 260 for traditional areas and RRIM 600&GT1 for non-traditional
areas
•2. RRIM 600,GT1,PB 28/59,PB 217, RRIM703,RRII 203 et
•3.There are a number of promising clones: PB86,BD5,BD10,PR17,RRII5,50, 51,
109, 116,300, 308,PCK1,PCK2,Tjir1etc

13. RRII105
(Hybrid
clone)
•RRII105 is the highest yielding in the world
•A clone evolved by the Rubber Research Institute of India
•Maily grown in India
•Parents are Tjir 1 and GI -1
•Stem tall and straight
•Occupies 80% of area under rubber
•Its av. Yield is 2425 kg/ha in large scale during ten years of tapping
•Highly susceptible to Pink disease
•Fair degree of tolerance to abnormal leaf fall disease
RRIM600 •Hybrid of Tjir I x PB 86 popular in non traditional areas of NE
states of India
•Tall straight stem
•High yielder
•Commercial yield in India over 20 years is 1340 kg/ha/yr
•Highly susceptible to Phytophthora and Pink disease

14. GTI •An outstanding clone developed in Indonesia
•Stem Upright, variable branching habit shows increase in yield trend
•Commercial yield in India is1359 kg/ha/yr during 10 years of tapping
•Good tolerance to pink disease and average tolerance to Phytophthora
•Withstands higher intensities of tapping and well suited for small
growers.
PR 107 •Primary clone developed in Indonesia.
•Sturdy, wind resistant
•In India average yield over 19 years under commercial planting is 1044
kg/ha/yr.
•Withstands higher intensities of tapping.
•Susceptible to Phytophthora and Tolerant to Powdery mildew.

15. Tjir 1 •An Indonesian primary clone
•Vigorous, crown heavy, liable to wind damage
•Average commercial yield in India over 15 years is 978 kg/hr/yr
•Highly susceptible to Phytophthora, Oidium and Pink disease
•Latex yellow in colour.
GLI •A Malaysian primary clone
•healthy canopy with characteristic glossy bluish green leaves
•wind resistant
•susceptible to Brown blast
•have some degree of drought tolerance
•The average commercial yield in India over 15 years is 1127 kg/ha/yr.

16. PB86 •A Malaysian primary clone of slow growth,
•Not liable to wind damage
•Suitable for planting in exposed areas
•Yield high, latex white, prolific seeder
•Highly susceptible to abnormal leaf fall and shoot rot
•Performs well in Kanyakumari district where incidence of this disease
is very mild
•Commercial yield in India over 10 years is 1129 kg/ha/yr.
PB5/51•A promising clone evolved in Malaysia by crossing PB 56 and PB 24
• Stem straight and upright branches
•Commercial yield during 10 years of tapping is in India, it is 1261
kg/ha/yr
•Highly resistant to wind damage
•Average tolerance to phytophthora and below average tolerance to
brown blast and pink diseases
•Highly susceptible to Powdery mildew.

17. PB 28/59 •A Malaysian primary clone
•Susceptible to powdery mildew and pink diseases
•Highly susceptible to brown blast
•High yield with marked wintering depression
•Commercial yield in India over 10 years is 1369 kg/ha/yr.
RRIM628 •Hybrid of tjir 1 and RRIM 527
•Average vigour before tapping
•Poor after tapping
•Average commercial yield obtained in India over nine years is
1051kg/ha/yr
•Average tolerance to abnormal leaf fall and wind damage
•Highly susceptible to brown blast.

18. RRIM701 •Hybrid of 44/553 and RRIM 501
•Susceptible to pink disease, powdery mildew and wind damage
•The average commercial yield over eight years in India is 1042
kg/ha/yr.
RRIM703 •Hybrid of RRIM 600 x RRIM 500.
•Tolerance to Powdery mildew
•Susceptible to brown blast and wind damage
•In Malaysia, average commercial yield over 13 years is around
1725 kg/ha/yr.
RRII 118 •A hybrid of Mil 3/2 x Hil 28
•stem tall and stout
•The mean estimated yield during four years of tapping is 1850
kg/ha/yr
•Average tolerance to diseases.

19. RRII 203•A hybrid of PB 86 x Mil 3/2
•Stem straight and tall
•Estimated yield from large scale trial over four years is 1675
kg/ha/yr
•Average tolerance to diseases
RRII 208•A high yielding hybrid clone in initial years of tapping
•parents are Mil 3/2 and A VROS 255
•High susceptibility to Shoot rot
•Estimated yield from large scale trial over four years is 1685
kg/halyr.
RRII 414 •All the 400 series hybrids of RRII 105 AND RRII100
•Highest yielder among the most recently released 400 series clones
•Tall straight& cylindrical trunk
•45% yield increase over RRII105

20. Other promising clones identified are
•PB 6/9 (PB24 x PB28)
•PB 217 (PB 5/51 x PB 6/9)
•PB 235 (PB 5/51 x PB 9/78)
•PB 255 (Tjirl PR 107)
•PR 261 (Tjirl x PRI07)
•PB 260 (PB 5/51 x PB 49)
•PB 280 (PBIG seedling selection)
•PB 311 (RRIM 600 x PB 235)
•RRIM 605 (Tjirl x PB49)
•RRIM 623 (PB99 x Pil B 84) etc.

21. Propagation
•By seeds & budding. Modified forket and patch budding
•Rootstocks are raised in nursery beds by sowing seeds
•Sseeds germinate in 6-7 days
•Germinating seedlings are transplanted in the 2
nd
nursery
•2-8 months old seedlings are used as rootstocks
•Green/Brown buds in the form of a patch are collected from 1 yr. old bud wood
• For green buds 2 months old rootstocks used
•For brown buds 8-10 months old rootstocks are used
•Union takes place in 4 weeks, top portion of root stock above the bud joint is
removed and planted in large polythene bags the bud will start sprout in two weeks
•One year old budded plants are planted in main field

22. Nursery
•Seeds collected during July-Sep. in South India
•Viability of the rubber seeds is short (8 weeks by storing)
•Collected every day & sown immediately as they loose viability if left exposed in
the field for more than 3 days
•Raised sand beds of required length are prepared
•The seeds are sown with the surface of the seed just visible above and pressed
firmly, temporary shade is provided
•The nursery bed is kept moist (but not wet) by sprinkling water during early
mornings and late evenings
•Seeds start germination within 6-10 days of sowing
•Every day germinating seeds with radicle alone should be picked and planted in
the secondary nursery

23. Main field preparation & planting
•Season - june-july
•At first the selected area is cleared
•Pits of 1x1x1m size are formed at recommended spacing
•Filled with top soil
•One year old buddlings/seedlings are planted at the centre of the pit by keeping the
bud joint above the ground level
•Squre or rectangular system is adopted in plains
•Contour planting with continuous terrecing is followed in hilly slopes

24. Spacing
The common spacings adopted are:-
(i) For buddings
•In hilly areas - 6.7 m x 3.4 m - 445 plants/ ha
•In flat areas - squares - . 4.9 mx4.9 m - 420 plants/ha
•Triangular - 4.9 m x4.9 m - 470 plants/ha
(ii) For seedlings
•In hilly areas - 6.l mx3.0m - 539 plants/ha
•In flat lands - 4.6 m x4.6 m - 479 plants/ha

25. Manuring- Seedling Nursery
• Manuring is done with the objective of producing maximum number of healthy
and vigorous seedlings per unit area.
• Incorporation of 25 kg of compost and 2.5 kg of rock phosphate per 100 sq.
meter of the nursery bed
• Application of rock phosphate can be made once in three years.
• Application of 2500 kg of 10:10:4:1.5 NPK Mg mixture/ha i.e., 25 kg per 100
sq. m of the nursery bed, 5 to 6 weeks after planting.
• Application of 550 kg of urea/ha, 6-8 weeks after the first application but before
mulching.
• Applied about 8-10 cm away from the base of the plants in a 14 cm wide linear
band in between two rows and gently forked in with a hand rake.

26. Manuring - Budwood nursery
•The aim of manuring bud wood nurseries is to obtain maximum quantity of bud
wood of good quality, during a period of 10-12 months with an initial period of 12-
18 months for the first usage of bud wood
•Incorporate 150 kg of powdered rock phosphate per ha
•i.e., 1.5 kg/100 m
2
of the nursery bed as basal dressing at the time of preparing the
nursery bed.
•Apply 250 g of 10:10:4:1.5 NPK Mg mixture per plant in two split doses of 125 g
each. Give the first dose 2 to3 months after planting and the second dose 8 to 9
months after planting
•Application of 125 g of 10: 10:4: 1.5 NPK Mg mixture per plant in one single
application 2-3 months after cutting back for the second and subsequent crops of
budwood from the nursery.

27. Manuring - for immature rubber tree
•For immature rubber plants at pre-tapping stage
•FYM or compost-12kg
•Rockphosphate-120g
•NPKMg10:10:4:1.5 for Mg deficit soils or 12:12:16 NPK alone for Mg rich soils
as per the following schedule
For matured tree under tapping
•Apply NPK 12:12:6mixture @400kg/ha every yr in two split doses
•Add 10kg commercial Magnesium sulphate for every 100kg of the above mixture if
there is Mg deficiency

28. Manuring
MAP Period of application
Quantity /plant(g)
10:10:4:1.5
Quantity /ha(kg)
12:12:16
3 Sep-oct 225 g 190 kg
9 April-may 445 g 380 kg
15 Sep-oct 450 g 380 kg
21 April-may 450 g 480 kg
27 Sep-oct 550 g 480 kg
33 April-may 550 g 380kg
39 Sep-oct 450 g 380kg
From 5
th
yr onwards till the tree is ready for tapping apply 400 kg of mixture/ ha in 2 split doses,
once in April-may and another in Sep-Oct

29. Method of application
•1
st
application is given in a circular band around the base of the young plant 7 cm
away from the base
•2
nd
application 15 cm away from the base
•The radious gradually increases with increase in age of the plant until the canopy
closes
•From 5-6 yrs. Onwards fertilizers are applied in small patches & forked into the soil
in between the rows with each patch serving 4 trees
•If there is good cover crop broadcasting is also sufficient

30. Nutrient deficiencies
Mg deficiency is most common - Interveinal chlorosis is its main symptom
K deficiency- Marginal & tip chlorosis followed by marginal necrosis are the tipical
symptom of K deficiency. Reduction in leaf size is also occur.
Zn deficiency - Interveinal chlorosis, leaves become narrow & elongated. Leaflets
become curved giving a claw like appearance
Mn deficiency- Overall yellowing with green bands along the midrib & veins
Excesses Mg - pre-coagulation of latex on tapping panel

31. Cover crops
•The object of growing cover crops is
•to prevent soil erosion, conserve soil moisture, keep down the soil temperature and
add mulch and organic matter to the soil
An ideal cover crop should be
•perennial, easy to establish,
•rapidly growing to form good cover without affecting the growth of the rubber,
•able to stand slashing and shade, have good soil building properties
•Have the ability to suppress weed growth, must be resistance to drought, pests and
diseases
•and if possible unpalatable to cattle with high nitrogen fixing capacity
•The following are the cover crops used : Calopogonium muconoides, Pueraria
phaseoloides, Centrosema pubescens, Desmodium ovalifolium, Mimosa invisa var.
inermis

32. Mixed cover
•A few of the desirable characters of cover crops for rubber plantations are
•rapid initial growth for early covering of ground
•dense vigorous growth to suppress weeds
•and continued growth for as long as possible during the period when overhead
shade increases
•None of the cover crops commonly used have all these attributes, Hence, it is
desirable to establish a mixed cover
•A mixture of Calopogonium, Pueraria and Centrosema seeds in the ratio of 5: 1:4
is used for sowing in Malaysia
•In this mixed cover, Calopogonium grows rapidly and covers the ground quickly
during the first year itself.

33. •Then Pueraria and Centrosema start dominating
•Dense and vigorous growth of Pueraria suppresses weeds
•But it starts fading out when the canopy closes.
•Subsequently, Centrosema continues to grow under shaded condition while the
former two cover crops fail to thrive
•Thus complete benefits of cover crops starting from the first year of planting could
be obtained, if mixed cover crop are established in rubber plantations
•Seeds of cover crops are objected to pre treatments such as acid treatment, hot
water treatment, abrasion etc. for ensuring good germination.
Mixed cover

34. Weed management
•Eupatorium, Lantana, Mimosa pudica and Imperala cylindricae are important
weeds found in the rubber plantations
•Regular weeding is necessary until the cover crop is established
•During the first 2 yrs.4-5 rounds of hand weeding are required
•Once the cover crop is established or the canopy has closed there is little weed
growth
•When weedicides are employed, care should be taken that the cover crops are not
affected
•It is recommended that 2, 4-D formulations (Fernoxone 2 kg in 450 liters of water)
may be sprayed early in the season to eradicate weeds.
•Simazine controls broad leaved weeds and grasses applied as pre-emergence spray
at 12 kg/ha

35. Tapping
•Latex produced in the bark tissue is extracted by a process called tapping
•Tapping is the periodical removal of thin slices of bark of less than 1mm thickness
to extract rubber latex
•The latex vessels are found in the inner layer of soft bast of the bark.
•During tapping latex containing laticiferous vessels which are concentrated in the
soft bark & arranged in a serious of concentric rings of interconnecting vessel is cut
open
•The distribution of this vessel varied in seedlings but not on budded trees.

36. •Tapping is initiated when about 70% of the trees in a plantation attain tappable girth
•Tapping is done by skilled men
•While tapping, the cambium should not be damaged as otherwise callus formation
will take place-causing swellings
•The rubber trees attain tappable stage in about seven years, provided they possess
the required girth of the trees
•First tapping in a seedling tree will commence when the trunk attain a girth of 55
cm at 50cm ht. from the ground level
•In budded plants 1
st
tapping is done when the trunk attains a girth of 50cm at a ht.
of 125cm from the bud union
Tapping

37. •The best season for tapping is March or September depending upon the girth of the
tree
•Tapping has to be done on a slope of 30° to the horizontal in case of budded trees
and 25° in case of seedlings
•Different slopes are given because of difference in the thickness of the bark
•In budded trees since the bark is thin, slope is given at 30° angles, whereas it is
thick in case of seedlings
•Slope should be marked annually
•The tapping cut is also called tapping panel
•The tapping should not be steep as it leads to wastage of bark and overflow of latex
Tapping

38. •The best yield is obtained by tapping at a depth of less than 1mm close to the
cambium so that the cambium is not injured
•The latex vessels in the bark flow at an angle 32° to the right and therefore a cut at
a higher level from the left to right has to be carried to facilitate opening of a larger
number of latex vessels.
•Tapping is done in the early morning when turgor pressure for exudation of latex is
maximum
•late tapping will cause reduction in the flow of latex occurs
•A sharp knife called Michie Golledge gouge is popular in India used for latex
extraction
Tapping

39. •At each tree the taper 1
st
collect the previous day’s dried latex adhering to the
grooves of tapping cut and in the cup
•This scrap is collected in separate bag
•Then a thin strip of bark is removed from the groove
•The latex flows down along the groove of the cut surface and fall in the cup placed
in a wire hanger attached to the trunk
•The first shallow cut is deepened by tapping two or three times before the collection
of much latex
•The cut should be made in a regular slope with evenness
• After each tapping, the latex flows for a while and then stops because of
coagulation, which plugs the latex vessels
Tapping

40. •These plugs are very small
•During next tapping, a thin shaving of bark is erased off to remove the plugs.
•The tapper moves to next tree and so on
•After few hrs, when the latex ceases to flow it is collected from the 1
st
tree
•At the end all the utensils used were cleaned
•By regular tapping the tree is trained to produce rubber continuously
•During Dec-Feb the latex yield is low& tapping is stopped for about four weeks
•The trees are provided with rain guards
•Rain guarding is nothing but protecting the tapping panel and the cup with
polythene sheats from rains to help in non stopage of latex extraction
•Attached to the trunk above the tapping panel
Tapping

41. •The tapping panel is
usually made as a spiral
around the trunk covering
half of the girth
•Tapping is generally done
once in 3 days.
•Tapping is done early in
the morning using a special
knife
•On an average, a tapper can
tap about 300-400 trees/day
Tapping

42. Tapping

43. Tapping system
•The widely adopted tapping systems are half spiral, alternate daily (1/2 s d/2) and
half spiral third daily(1/2 s d/3)
•Trees that follow 1/2 s d/2 system are said to be under 100% tapping intensity other
tapping systems are
•High panel tapping, controlled upward tapping, panel change, low intensity tapping
and high intensity tapping
•For the first 6 years tapping is done on one side (panel A) of the tree from the top to
down
•In the next 6 years the tree is tapped downwards on the opposite side (panel B)
•During third year the renewed bark on the first side can be tapped again (panel C)
panal D is also attended

44. •However, it is better to adopt Controlled Upward Tapping (CUT) of the virgin bark
above the first panel instead of tapping the renewed C panel
•A modified knife with a long handle is used for CUT.
•Here, frequency of tapping can also be once in 3 days or even shorter with yield
stimulation
•Half spiral or even shorter cuts are practiced more recently.
•The application of dilute (1-5% active ingredient) ethephon (2-chloro ethyl
phosphonic acid) on the panel or on the bark at prescribed intervals and seasons
enhances the yield
•During rainy seasons tapping can be done by fixing suitable polythene shades as
rain guard over the tapping panel
Tapping system

45. •During extreme climate such as drought and severe winter tapping rest is
commended for a couple of weeks to avoid stress to the trees
•The national average yield is 1.6 tonnes/ha/yr
•The average yield of a well-managed plantation of RRII 105 is 2.4 tonnes/ha/yr
which can be still higher in better plantations.
•Latex contains on an average 32% dry rubber content
•After tapping, latex drips for 1-2 hr are collected in small cups
•Once the dripping is over, the latex is collected from the cups and processed into
either crepe rubber, sheet rubber, preserved latex, latex concentrate or block rubber.
Tapping system

46. Rubber processing
•The most common and widely followed processing is sheet rubber making.
•For this, latex is coagulated in suitable containers after proper dilution with water
and by mixing with dilute acetic or formic acid (coagulants)
•The coagulum is pressed in rollers to make sheets which are dried in sun for a few
hours
•The sheets are then dried in a smoke house (40°-60°C).
•Various types of smoke houses (permanent/mobile) are available
•About 4-5 days are enough to dry these sheets in a smoke house.
•Dried sheets are graded into different categories
•The sheets after grading are packed in vales of 50kg weight and marketed.

47. Physiological disorders
•Tapping panel dryness (TPD) is the only major physiological disorder
affecting the rubber tree characterized by partial or complete drying up of the panel
(i.e. no production of latex) after a period of prolonged and late dripping of latex for
a few days/weeks
•Some trees become dry even without late dripping
•In some dry trees, tumors and necrotic bark tissues develop along the bark
•The affected soft bark becomes light brown in colour and hence TPD is also known
as brown bast
•The outer bark get dried and cracks open
•Tumors can be seen on the panel area
•Otherwise, the tree continues to grow normally

48. •The exact cause of this syndrome is unknown
•excessive harvesting of latex seems to be a possible trigger and high-yielding
clones are more vulnerable
Control
•Giving tapping rest is the only recommendation at the moment, but this is not a
fool-proof solution
•Low frequency tapping is also recommended which will reduce the incidence of
TPD.
Physiological disorders