VIETNAM
Agriculture réhabilitation Prqjdd;
Rüiibér rehabilitation
Jean Campaigrtqîle
27July - 11 September 1995
VIETNAM
A griculture réh ab ilitatio n Project
R ubber rehabilitatio n co m ponent
J e a n Campaignolle
2 7 Ju ly - 11 S eptem ber 1995
Sum m ary
Term s of reference (sho rt-term co n su ltan t)
M ission report
Annex :
S itu atio n of th e p la n ta tio n s
P lan tatio n m ission n o te s :
Areas a n d estim ated yields of the
p la n ta tio n s in 1995
Progress of yields from 1992 to 1995
(estim ated).
Dong Nai
Laikhé
(1 A ugust 1995
(3
(8
(10
-(12
-(16
-(18
-(22
-(24
-(29
-(31
-D au Tieng
Dong Phu
Binh Long
Ba Ria
Tay Ninh
Loc Ninh
Tan Bien
Phuoc Hoa
Phu Rieng
TERMS OF REFERENCE
SH O R T-TERM ROBBER PLANTATIO N S _ A DVISER
The
s h o r t - t e r m
consultant
appointed
to
p r o v i d e
p r e l i m i n a r y
technical inputs, p r i o r to the arrival of the l o n g - t e r m resident
adviser should, during the 2.5 months of his mission, focus upon
the p r i n ciple requirements of points 'c.', 'd.' and '
e.' of the
Terms of Re f e r e n c e of the l o n g - t e r m adviser.
He should therefore concentrate upon the following :
Carry out a rapid programme of visits to each of the ten
State Rubb e r Companies (SRCs) of the pro j e c t to examine/
review standards of p l a n t a t i o n m a n a g e m e n t h u s bandry
which, in the following order of priority, will lead to
-Firstly, the identification of training needs and, in
concert wi t h the resident G RC T r a i n i n g Adviser, assist in
the o r g a n i s a t i o n of appropriate training courses and in
the p r e p a r a t i o n of
training aids
and m a t e r i a l s
as
r e q u i r e d .
Secondly, advise the GRC and the SRCs of the recommended
best p l a n t a t i o n m anagement h u s b a n d r y practices,
and
ensure the transfer of expertise in so doing.
Thirdly, m o n i t o r the appli c a t i o n / u s e of the agricultural
inputs p r o c u r e d under the project and s upplied to the
SRCs (stimulant, fungicides, w eedicides and f e r t i l i s e r s ) .
A
Miss i o n Report should be p r e p a r e d in English, p r i o r to departure,
and p r e s e n t e d to the PCU at an end-of-a s s i g n m e n t seminar.
Identification o f training needs and assistance in the organisation o f
appropriate training courses and preparation o f training aids a nd materials
required.
The n e e d s are su b sta n c ia l. They co n sist of tra in in g perso n n el and
equipping it so th a t it c a n c a riy o u t its w ork well. S u ccess depend on
a com bination of knowledge a n d facilities.
T ra in in g r e s e a r c h e r s
(acquiring knowledge)
O perations sh o u ld s ta r t w ith th e train in g of IRCV re s e a rc h e rs, who
should gain knowledge by them selves a n d / o r p a s s on th eir
knowledge to o thers. There are several w ays of doing this.
S h o r t t e r m f e llo w s h ip s
S tays in o th e r co u n tries lasting from 2 w eeks to a m o n th are to be
p lan n ed in m o st fields, a n d in a n y case in th o se th a t have received
aid from th e World B ank. This c o n cern s qualified re se a rc h e rs in the
following divisions :
- Physiology/Exploitation (tapping, stim u latio n a n d latex
diagnosis),
- A grochem istery (this covers the problem of fertilisatio n a s
th e w ork c o n cern s the second or even the th ird generation of ru b b e r
trees,
b ecau se plowing h a s been over-used on th e p retex t th a t
th ere are plenty of m en a n d m ach in es a n d finally intercropping h a s
been u se d frequently in th e th re e first y ear of cultivation).
- a n d Crop Protection (problem of Imperata control, care to be
applied to tre e s in case of Corticium salmonicolor a n d Phytophtora
palmivom).
V arious IRRDB in s titu te s w ould seem to be highly su itab le for
tra in in g th e se re s e a rc h e rs :
- Physiology/E xploitation : CIRAD-CP,
R u b b er R esearch
In stitu e of India (RRII) a n d possibly th e R u b b er R esearch In s titu te
of M alaysia (RRIM), e tc ... w hich have perform ed w ork in tapping,
stim u latio n , tree p an el d ry n e ss, latex diagnosis, etc...
- A grochem istry/F ertilisation : am ong o th ers, th e In dian a n d
M alaysian in s titu te s have long experience in fertilisation a n d
m ineral (and possibly organic) m onitoring of ru b b e r tree n u tritio n
u sin g soil a n d leaf an aly ses. An im p o rta n t role sh o u ld be given to
th e com p u terised processing of a n a ly se s a n d calcu latio n s.
However, o th er in s titu tio n s are also qualified to a d m in iste r su c h
training:
- for exem ple, two y ears ago an Indian re se a rc h e r w as
aw arded a g ra n t for fu rth er train in g in tiss u e c u ltu re in th e U nited
S ta te s w ithin th e fram ew ork of a n operation program m ed by the
In tern atio n al R ubber
R esearch a n d D evelopm ent Board (IRRDB),
w hich asso c ia te s all th e n a tu ra l ru b e r re se a rc h in s titu te s in th e
world, for train in g 8 IRRDB m em b er-in stitu te re s e a rc h e rs p er year;
the V ietnam ese In s titu te (IRCV) h a s also benefited from this;
- m ore recently, R otham sted E xperim ental S tatio n (UK) h a s
agreed to tra in re s e a rc h e rs for th e IRRDB for periods of several
m onth s. F our su c h co u rses are p lan n ed for 1995.
F urtherm ore, som e re s e a rc h e rs of IRCV m u s t be able to a tte n d the
IRRDB a n n u a l m eeting. In 1995 th is m eeting will take place in
Penang, M alaysia. 3 p e rso n s could go there.
O v e r se a s m a s t e r s d e g r e e s
Work can be done on "theses" for m ore in -d ep th basic train in g in a
neighbouring co u n try th ro u g h the n ational ru b b e r re s e a rc h in stitu te .
M alaysia h a s j u s t accepted two p o st-g ra d u a te d s tu d e n ts from IRCV
-one for train in g in Physiology/Exploitation a n d th e o th e r in
A grochem istery (fertilisation).
In th e p re se n t case, for e ith e r a sh o rt term fellowship or an
overseas m aster, th e can d id ate for train in g does n ot have to concern
him self w ith th e expen d itu re on staff a n d eq u ip m en t in cu rred by the
host. It is u p to the h o st in stitu te to charge th e in stitu tio n t h a t h a s
se n t th e p erson to be trained.
T e c h n ic a l A s s i s t a n c e
It is th e second possible way of train in g IRCV research ers. The
perso n ad m in isterin g th e train in g is invited in th is case. V isits by
high-level p e rso n s can last for two w eeks to à m onth, d u rin g w hich
th e ir exp en ses (and th eir fees) m u st be covered a n d w orking
facilities provided : lecture room , vehicle, equipped laboratories, etc.
For exam ple,
teach in g
in
Physiology/Exploitation
c a n n o t
be
conceived w ith o u t a n appropriately equipped laboratory. In th is case,
the c o n s u lta n t ch o sen m u s t explain how to u se th e eq u ip m en t in
th e b e st way. This is especially in projects like th e p re s e n t WB
operation in w hich th e eq u ip m en t h a s been com pleted a s b est a s
possible. Som ething m ight well be lacking, ... for exam ple a
g en erato r set to r u n it all.
However th is m ay be, th e following a sp e c ts m u s t be explained in
o rder to set u p a latex diagnosis system :
-how to m ake sam pling of latex in th e p lan tatio n lock in
qu estion (n u m b er a n d d istrib u tio n of sam p les p er u n it a re a of clone,
th e latex sam pling technique to be u sed according to the p a ra m e te r
to be analysed -th ere a re generally 4 p aram eter-, the eq u ip m en t to
be carried in th e fields a n d th e qu estio n of transport);
-once th e sam p les have been tak en to the laboratory, how to
analyse th em w ith th e a p p a r a tu s available (this q u estio n will have
been settled in advance);
-how to u se th e raw d a ta a n d in te rp re t th e re s u lts according
to clone, tree age a n d tapping, in sh o rt in the light of th e tree "past";
-finally, w h at should be said to the p la n te r to possibly enable
him to a d ju st h is tap p in g system .
Likewise, th e following a s p e c ts m u s t be exam ined in th e a n a ly sis of
th e n u tritio n a l sta te of a s ta n d (clonal) :
-how to tak e soil sam p les a n d possibly leaf sam p les (num ber
a n d d istrib u tio n of sam ple p er u n it of clone a re a -th is is n o t easy for
leaves- a n d the time w hen sam pling should be carried out,etc...);
-how o an alyse the soil sam p les a n d leaf sam p les w hen they
have reached th e laboratory (preparation of sam p les for a n aly sis a n d
th e a n aly sis them selves, etc...);
-su b seq u en tly , how to in te rp re t the re s u lts of an a ly sis in the
light of th e clone, th e fertiliser applied in the p a st, etc..
-finally, th e fertiliser reco m m en d atio n s to be m ade to the
p la n te r for th e plot in question.
The laboratory m u s t also be ready in term s of eq u ip m en t a n d staffed
by qualified p erso n s. There is a m ajor disad v an tag e in th e system of
equipping a laboratory a n d sim u ltan eo u sly sending its staff ab ro ad
for training. There is no point in having a perfectly equipped
laboratory th a t the staff c a n n o t u se properly. It is b e tte r to devote a
few w eeks to train in g a n d th e n be able to ru n th e laboratory
properly.
However, th e re is a limit to th is reaso n in g th a t is reach ed in the
case of overseas m a s te rs w hen th e p e rso n s concerned stay ab ro ad
for two or th re e years, in p a rtic u la r to w rite a th esis. Experience h a s
show n th a t w hen they re tu rn to th e ir co u n try w ith th e ir new
qualification, they co nsider th a t they m erit b e tte r th a n w h a t th eir
in s titu te -IRCV- is able to offer th em a n d they leave for th e pivate
sector. There are recen t exam ples of th is :
-two successive form er h e a d s of th e Physiology Division left
IRCV after m an y train in g c o u rse s ab ro ad to enable th em to m ake th e
m o st of th e ir laboratory;
-likewise, the form er h ead of th e A grochem istry Division, who
w as beginning to acquire good m astery of h er field an d who h a d
sta rte d u p th e IRCV soil a n d leaf a n aly sis laboratory, w as
tran sferred to the B oard of GRC.
There are two w ays of solving th is problem :
(1) pay IRCV re s e a rc h e rs b e tte r salaries ; it is generally agreed th a t
th e pay is n o t attractive;
(2) have th e re se a rc h e rs sign c o n tra c ts before they go ab ro ad in
w hich they u n d e rta k e to stay w ith IRCV for 5 y e a rs w hen they re tu rn
w ith th eir new qualification. This m e a su re is beginning to be
applied.
T r a in in g p la n t e r s
(transfer of technology)
The need of training m ay involve p la n te rs who display a certain
degree of o p e n -m in d ed n ess or even legitim ate curiosity. There is no
reaso n to deprive them of knowledge, a t least in general term s. One
does n ot do well w h at one does n o t u n d e rs ta n d a n d n ot
u n d e rs ta n d in g m ay lead to lack of in te re st in th e su b ject th a t is bad
for the work to be done or simply for the operation of settin g it up.
The p la n te rs sh o u ld therefore be given th e full d etails of w h a t is
suggested th a t they sh o u ld do on th e ir holdings, especially
concerning th e w ork involving labo rato ries (Physiology / Exploitation
a n d Agrochemistery). All o p p o rtu n ities sh o u ld be used , su c h a s
visits, talks, etc..., n o t forgetting IRCV b ro c h u re s a n d leaflets th a t
can go fu rth e r into explaining su c h subjects.
In addition, v ario u s co m p o n en ts of som e te c h n iq u e s can be a ss ig n e d
to the p la n ta tio n s, leaving th e lab oratories to play th eir tru e role.
P lan ters could be train ed to tak e soil, leaf a n d latex sam ples, etc. It
is n ot very difficult b u t req u ires knowledge. The sam p les collected
w ould th e n be se n t to IRCV for su b s e q u e n t opérations.
In a n y case, all th e knowledge gained is finally aim ed a t the
p lan tatio n s. IRCV h a s two possible lines of ap p ro ch :
- eith er show ing th e re s u lts o b tain ed a t th e In stitu re itself,
- or organising a d em o n stratio n a t a p lan tatio n a n d inviting
th e o th e r p la n te rs to atte n d .
This is th e role of th e d e m o n s t r a t io n s fis s e m in a r s funded by the
WB.
There have been m any of th e se d e m o n stra tio n s a n d s e m in a rs in
recen t years. The following can be m entioned :
- p a s t events w ith local funding :
. 1994, a d em o n stratio n a t Laikhc of re s u lts u sin g :
. glyphosate (to replace la b o u r a n d m achines)
. validam ycine (to replace B ordeaux mixture)
. ridomil (to replace difolatan w hich h a s been
forbidden);
- fu tu re o p erations to be p repared (and proposed for WB
funding) :
. 1995, d em o n stratio n of new clones a t Laikhé a n d Dong
Phu, a se m in a r organised by the Breeding
Division;
u se of agrochem icals in d isease a n d land control +
dem ostratio n of spraying equipm ent, a sem in ar
organised by the Crop Protection Division.
Needless to say, oral in stru ctio n m u s t be backed u p by one or m ore
d o cu m en ts settin g o u t th e ideas, listing th e re s u lts of a n a ly se s a n d
showing prices. There is no d o u b t th a t if p la n te rs a ie convinced by
the talk (and th e low prices), they will w a n t to re p e a t the
ex p erim en ts on a sem i-in d u strial scale on th eir own p lan tatio n s.
One perso n is eno u g h to lead th e others.
This w ritten w ork is im p o rtan t. IRCV re se a rc h e rs sh o u ld devote
them selves to it not only b ecau se it is a n o p p o rtu n ity for th em to
clarify th eir ideas b u t above all b ecau se it provides scope for
han dling any objection to the application of a new technique. In fact,
they do this.
A dvise the GRC a n d SRC s o f the recomrnanded best plantation management
and husbandry pratices and ensure transfert o f expertise.
Theie is no qu estio n in th e project of defining th e vario u s p lan tatio n
tech n iq u e one by one.The m ost im p o rta n t one will be exam ined.
-Land preparation
In th e light of w h a t we have seen, land p rep aratio n is perform ed with
care. Previous g eneration ru b b e r trees are felled a n d m axim um u se d is
m ade of th e tim ber. It sh o u ld not be forgotten th a t the sale of tim ber
covers th e funding -a t least for th e m om ent- of a large proportion of th e
rep lan tin g costs, while still allowing local population to collect sm all
wood for dom estic needs. Wood is becom ing increasingly scarce in m any
Asian co u n tries a n d ru b b e r wood will play an increasingly im p o rtan t role
in p lan tatio n econom ies. There is even talk of m aking ru b b e r a crop with
the twofold objective of producing latex a n d Wood.
-Imperata control
This m u s t be perform ed vigorously. It is u n an im o u sly considered th a t
glyphosate tre a tm e n t gives good re su lts. The CDA, a n individual
k n ap sack sp ray er ru n n in g on a sm all built-in electric m otor, is easy to
u sed (mainly for th e young imperata)
-D e n s itie s
It is a fact th a t low d ensity a re a s are observed in old p la n ta tio n s. Wind
breakage is difficult to prevent alth o u g h clone re p u te d to be r e s is ta n t ca n
be chosen. In th is respect, PB 235, w hich is extensively p lan ted in
V ietnam , is p e rh a p s n o t the b est choice.
One way of co m p ensating for loss by wind breakage in advance is to p lan t
a t a higher density. P lanting u se d to be carried o u t on a 5m x 5m square
b asis w hich th u s gave 25 m2 per tree a n d 400 tre e s per hectare. However,
th in g s have ch anged a n d d en sities are reported to be a s follows :
-in red soil : 6m x 3,5m ; i.e. 21 m2 per tree a n d 476 trees p er h a ;
-in grey soil : 6m x 3m , i.e. 18 m2 per tree a n d 555 trees per ha.
It is noted th a t th ere h a s also been a change to a re c ta n g u la r layout.
This m ak es th e tap p ers' w ork easier a n d finally re s u lts in a possible
increase in th e n u m b e r of tre e s tap p ed in each tap p in g task .
P lanting is carried o u t well w ith perfect alig n m en ts in both directions.
It is noted th a t n e a r th e e q u a to r a n east-w est alignm ent affords b e tte r
exposure to su n lig h t for in tercro p s th a n a n o rth -s o u th alignm ent.
•
•
Three m ain clones are u se d in th e GRC e s ta te s : GT 1, RRIM 600 a n d PB
235. This is few a n d even veiy few. More th a n h alf of th e a re a of som e
e s ta te s co n sists of PB 235. One m ight say why n o t th ese clone ? B ut
th ere are o thers. It is n ecessary to progressively enlarge a n d diversify th e
genetic base of th e estate. A bout ten different clones w ould be a
reaso n ab le target, w ith each of one rep resen ted in proportion to its
agronom ic a n d econom ic interest.
In addition, the budw ood garden sh o u ld be "auth en ticated ". G enetic
identification m e th o d s (electrophoresis) exist. The a n n u a l p lan tin g s a n d
rep lan tin g s in th e 1980s were veiy large (several th o u s a n d h e c ta re s per
e sta te
p er year).
This
n ecessarily
req uired
intensive
vegetative
m ultiplication a n d u n fo rtu n ately th is carries a risk of error. In an y case,
th e e s ta te s co n tain a n u m b e r of trees w ith failed budding, leading to a
variety of trees,-so m e still seedlings a n d th e o th e rs b u d d ed .
A re tu rn to e sta te p lan tin g s a n d rep lan tin g s of m ore reaso n ab le
d im ensions will be an o p portunity for improving the quality of work.
It is noted th a t a tiss u e cu ltu re p la n t p roduction tec h n iq u e (som atic
em bryogenesis a n d m icrocutting) h a s been tried a t IRCV. The d e p a rtm e n t
m an ag er h a s left b u t th e w ork sh o u ld be sta rte d again.
-In te rc ro p s
The need of local in h a b ita n ts to grow in tercro p s can be u n d ersto o d :
. they enable villagers to grow food while w orking on th e lan d
e n tru s te d to th em (they also have to m ain tain th e corresponding row s of
th e ru b b e r trees);
. e sta te m a n a g e rs have sm aller m a in te n a n c e ex p en ses for y o u n g
p lan tin g s.
It is rem inded th a t som e in tercro p s are beneficial for ru b b e r (soya,
g ro u n d n u t), o th e rs are merely acceptable (rain-fed rice a n d corn) a n d
o th e rs sh o u ld n ot be grown (cassava).
In addition, th e fertiliser p u rc h a s e d w ithin th e fram w ork of th e WB
project is n o t in ten d ed for in tercrops.
-cu ltu rale m eth o d s
One learn es a t school to to u c h th e surface ro o ts in a sta n d of tre e s a s
little a s possible.
Any m achine p assag e th a t m ay b re a k th e se surface roots should be
avoided. It is tru e th a t m achine p a ssa g e s in interrow s in the early y ears
w hen the roots h ardly extend beyong th e vertical line of th e edge of the
crown do n ot risk breaking roots. However, later, w hen th e ro o ts have
extended into th e interrow s, m ach in e r u n s sh o u ld be avoided. B u t a t
least th ree r u n s were recorded : th e first d u rin g imperata control (which
m u s t be ploughed in a t th e s ta rt of th e dry season) a n d th e two o th ers
d u rin g th e p lacem ent of fertiliser (in spring a n d au tu m n ).
Now th a t glyphosate is available, th e re is le ss fear of th is problem a s
imperata control is generally carried o u t in young plantings.
There re m a in s th e q u estio n of fertiliser, w hich is spread for m any years.
Fertiliser placed in the field m u s t be d u g in a n d
th is is th e problem
b ecau se a large proportion of th e surface root sy stem is c u t d u rin g th e
operation. The "blind drain" tech n iq u e exists in w hich p e rm a n e n t holes
are d u g for th e fertiliser, b u t th is en co u rag es theft. In sh o rt, th e problem
still req u ires a solution.
-m onitoring of growth a n d production
A fine ru b b e r tree is one th a t grows fast a n d well. The p la n te r m u s t know
w h eth er or not th e grow th of a certain clone is norm al so th a t he can
take an y n ecessary ste p s (e.g. fertilising) to try to rem edy an u n w an ted
situ a tio n in time. As it w ould be im possible to m e a su re all th e trees,
rep resen tativ e specim en s sh o u ld be ch o sen for m e a su re m e n t in each
clone block.
Likewise, it is im p o rta n t for a p la n te r to know h is production. The daily
collection reco rd s alone (with DRC m easu rem en t) give a good idea of
production potential. A bnorm al deviation sh o u ld be m onitored from one
ta s k to a n o th e r o r even in th e sam e ta s k m onitored two tap p in g days
running. The daily records sh o u ld be com pared w ith th e factory figures a
the end of each m onth. This type of w ork sh o u ld be carried o u t clone by
clone according to th e age of th e plots.
This kind of m onitoring sh o u ld be com puterised u sin g p rogram s designed
for th e p u rp o se (such pro g ram s m u s t exist). This should be one of the
first ta s k s to be carried out.
-Fertilisation of voung plantings
Application of WB fertilizer is in principle limited to im m atu re crops + 1
year. Of course, applying fertiliser to m a tu re cro p s does no h arm ,
especially to th e second or even th e th ird generation of ru b b e r trees a n d
w hen there are m an y intercro p s w hich draw soil re so u rc e s to varying
degrees from th e second generation of ru b b e r on w ard s ; however, th e real
ad v an tag es are d isp u tab le a t th e le a st
Application of fertiliser should in tim e be perform ed on th e b a sis of
recom m en d atio n s following soil analy sis, su b seq u en tly accom panied by
leaf analysis. It is n oted th a t leaf a n aly sis is only tru ly u seful if the
leaves are ch o sen on sho o ts w ith lim ited growth in th e leaf crow n ; th is
m e a n s th a t there m u s t be a leaf crow n or a t le a st the beginning of one
(seldom before th e tree is 3 or 4 y e a rs old).
Sam pling of soil a n d leaf is difficult to perform well (num ber of sam p les
per u n it area, sam ple d istrib u tio n in th e area, etc..). U nless the
tech n iq u es a re fully m astered , it is b e tte r to leave th e se o p eratio n s to
people who are u se d to them .
IRCV p o ss e sse s a w ell-equipped soil a n d leaf an aly sis laboratory a t th e
disposal of p lan ters. They should m ake a n agreem en t w ith IRCV to
e sta b lish a com m on program m e of sam pling a n d an aly sis (on a paid
basis).
-D isease control
T reatm en t is carried o u t regularly to control Corticium a n d Phytophtom,
taking into a c c o u n t c o n s tra in ts of n u is a n c e s a n d p rogress m ade :
. B ordeaux m ixture (with scraping) is being replaced by validam ycine
(without scraping) ;
. difolatan (no longer authorized) is replaced by ridomil (authorized).
No re m a rk s are called for on th is subject.
However, re s e a rc h e rs are in te re ste d in som e d ise a se s su c h a s Oïdium,
w hich c a u s e s th e fall of young leaves d u rin g refoliation, a n d they are
exam ining tre a tm e n ts. This is a jo b for IRCV. It sh o u ld be m entioned
th a t in Brazil, w here natio n al ru b b e r production is strongly com prom ised
by M icrocyclus ulei (a leaf d isease n o t found in Asia a n d Africa),
re s e a rc h e rs have yet to find a satisfactory control m ethod. Likewise, in
G abon, no satisfactory control m eth o d h a s been found for Colletotrichum
w hich h a s decim ated som e p lan tatio n s. It is d oubtful w h e th e r a m eth o d
will be found to prevent leaf shedding cau sed by Oïdium or to control
Phytophtora, etc. A s ta r t could be m ade by choosing clones th a t are
re s is ta n t to leaf d ise a se s.
Finally, it is useful to "see" w h at h a s been done in disease control. It is
therefore suggested th a t sp ray p ro d u c ts should include a dye so th a t the
tre a te d plots can easily be identified.
-Tapping
E state production is sm all a lth o u g h tap p in g is good or even veiy good.
T apping is generally of the S / 2 D /3 D /4 type w ith no stim u latio n . T his is
precisely h a lf th e tap p in g in ten sity u se d in th e p a s t w hen th e tre e s were
also stim u lated . O ne m ight w onder w h e th e r th e trees are n o t "sleeping"
to a certain extent. GT 1, a clone grown on th e sam e land in V ietnam
som e thirty y ears ago, yielded a b o u t 2 to n n e s per h ectare for y e a rs w ith S
D /3 D /4 stim u lated tapping. W hat is th e exp lan atio n ? Is it theft
(secondary qualities) ? This is possible, w hen one h e a rs th a t 10 000
to n n e s of ru b b e r is sold illegally .in V ietnam ; Is it b e c a u se of soil fatigue
c a u se d by large scale intercropphg a n d the fact th a t the second or th ird
génération of ru b b e r is now being grown ?
Finally, are th e tre e s tru e GT 1 (it is know n th a t th ere a re two in Africa
a n d one yields twice a s m u ch a s the other) ?
One could begin by stim u latin g them . Yield increase of 30 % h a s been
reported u n d e r stim ulation. In addition, they could be stim u la te d w ith o u t
w aiting for 5 y e a rs before starting. Indeed, if th e tre e s are opened for
tapping a t 7 y ears old, th is m e a n s stim u latin g from y ear 13 onw ards. The
q u estio n arises of w h ether, if a stim u latio n period is to be ch o sen , it
m ight n o t be b e tte r to stim u late a t the beginng of tap p in g ra th e r th a n
apply th e tech n iq u e to older trees.
Using latex diagnosis (L.D.) w ould be a way of forming a n opinion. It is
rem inded th a t th is m ethod is u se d to define o p tim u m tap p in g in ten sity
m aking it possible to avoid pro d u ctio n loss resu ltin g e ith e r from over
in ten sity of tap p in g leading to b a rk d iy n e s s or from letting tre e s "sleep".
The IRCV would have to be a sk ed to carry o u t th is work. There is a well-
equipped physiology laboratory a t Laikhe available to p la n te rs for th is
D.L. work.
The problem of RRIM 600 is sim ilar to th a t of GT 1. It is a clone th a n can
be norm aly stim ulated.
It is generally only n ecessary to be very c a u tio u s w ith m ore recen t clones
su c h a s PB 235. This clone n a tu ra lly gives its m axim um a n d hard ly n eed s
stim ulation. Let u s say th a t it sh o u ld be stim u lated w ith care a n d w ith
th e plots in q u estio n su b ject to L.D..
This inform ation will be h a n d e d to th e GRC w hich will d istrib u te it to
p lan ters. In d isc u ssin g it, th e p la n te rs will becom e involved in the
p ro cess of tra n sfe r of expertise.
B ut mainly, a t th e occasion of each of th e 11 visits (p lan tatio n s and
IRCV) realised by th e C o n su lta n t d u rin g h is m ission, th e m an a g e m e n t
were engaged in th e p rocess of tra n s fe r of expertise.
Monitor the application / u se o f the agricultural inputs procured under the
projectand supplied to the SRC s (stimulant, fungicides, herbicides and
fertilisers).
The 10 p la n ta tio n s + IRCV were visited a t th e ra te of one p er day,
followed by the tim e required to write no tes (1 day for each).
The 11 individual n o tes are provided a s a n ann ex . The re p o rts can
be recap itu lated a s follows.
H e r b ic id e
This c o n sists only of glyphosate for imjjemta control. This weed is
found in all th e p la n ta tio n s alth o u g h the q u a n titie s vary.
G lyphosate ord ers have been a s follows overall :
-1994 ap p ro x im ately 29% of th e re q u ire m e n ts a s a s s e s s e d by the
WB
-1995 : approxim ately 60% of the requirem ents.
The individual ord ers were staggered a s follows :
-1994 : 200 l.to 12 000 1.
-1995 : 600 l.to 12 000 1.
It is clear th a t before adopting a new p ro d u ct a n d a b an d o n in g the
old m ethod (removal of imperata by h a n d a n d by m achine), p la n te rs
w ished to gauge th e re s u lts them selves.
The 1994 o rder h a s arrived a n d h a s been u sed . Some p la n te rs
have stored som e an d , in c o n stra st, o th e rs have h ad to borrow
herbicide or even buy some on th e local m arket.
The 1995 o rd er should bring the situ atio n b ack to norm al
-although th e q u an tity is far from th e re q u ire m e n ts calcu lated by th e
WB- b u t it h a s n ot yet been delivered.
The 1996 order is not d isc u sse d here. It will be GRC's ta s k to
exam ine th e qu estio n w ith th e e s ta te s a t th e en d of th e year.
The re s u lts range from good to very good (better th a n dalapon).
This a c c o u n ts for p lan ters' e n th u s ia s m for glyphosate w hich is n ot
only effective b u t also avoids unw elcom e r u n s by m ach in es betw een
rows twice a year.
It w as also plan n ed to o rder sp ray ers -C.D.A. very low volume
sprayer- (roughly 3 litres p er h a in rows a n d 6 litres per h a in
interrows). This k n a p sa c k a p p a ra tu s h a s its own power supply
(battery).
Quite a large n u m b e r of p la n te rs have ordered C.D.A. sp ray ers (75
in 1994 a n d 120 in 1995). It seem s th a t th ere is a problem of u se : it is
easy to sp ray little -developed imperata or cu t back p la n ts b u t it is
difficult to handle-developed impemta (unfavourable sp ray er position
especially in wind, w hich is im p o rtan t for interrow crops). K napsack
sprayer w ith m a n u a l p re s su re sy stem s a ie u se d in th is case (they are
m ade locally a n d are cheaper).
Only one plantatio n h a s ordered a large spraying m achine. Ample
lab o u r is generally available. In addition, th e growing of interrow crops
is fairly w idespread a n d th is p revents th e u se of large spraying
a p p a ra tu s.
G lyphosate "works well" a s a whole.
F e r t i l i s e r s
These are N, P a n d K fertilisers in th e form of u rea, p o ta sh a n d
p h o sp h a te (Vietnamese rock phosph ate).
The o rd ers m ade by p la n te rs in 1994 all a tta in e d precisely th e
m axim um allowed by the WB. The 1995 figures are n o t a s precise a s
those of 1994 b u t a s a whole they all exceeded th e q uota, a s c a n be
seen below :
u re a
+ 18%
p o ta s h
+ 6%
ro c k p h o sp h a te
+ 16%
This m e a n s th a t fertilisers form a n e sse n tia l q u estio n for
p la n te rs .
The 1994 orders have all been used . The 1995 ord ers have not
been delivered except for p o ta sh in certain cases. The qu estio n of 1996
re m a in s to be seen b u t th e re will certainly be re q u e s ts for fertiliser?
The fertiliser is in ten d ed for young p lan tin g s + 1 year. N either
in tercro p s (m anagem ent of th e se is com pletely separate) n o r m a tu re
ru b b e r tre e s are included. This does n ot prevent p la n te rs from
p u rc h a sin g fertiliser on the m a rk e t for application to th eir m a tu re
trees (this practice sto p s w hen the trees are ab o u t 20 y e a rs old).
Fertilisers are generally mixed w hen they are to be u se d a n d
placed in two operatio n s : th e first a t th e beginning of th e ra in s a n d
th e second a t the end. They are tra n sp o rte d to th e site of u s e by c a rt
(tractor-draw n or other) a n d th e n la b o u re rs in th e p lan tatio n perform
spreading.
Fertiliser form ulas vaxy according to crop age a n d soil type (more
fertiliser is applied to grey soil th a n to red soil). The GRC se ts
fertiliser p lacem en t s ta n d a rd s .
To the b e st of my knowledge there arc no specific form ulas for
clones, alth o u g h the stock w ould be m ore concerned here. It would
n evertheless be simple for th e young crops a s th ere ai e only 3 clones :
GT 1, RRIM 600 a n d PB 235. The agrochem istry laboratory (soil a n d leaf
analyses) is only j u s t beginning to be u se d for possible a d ju s tm e n t of
th e GRC fertiliser form ulas according to clone (they play a role in
uptake), soils (as th e division betw een red a n d grey soils is r a th e r
sum m ary) a n d in general to all featu res of th e seaso n a n d th e place.
Some p la n te rs report a visit by Laikhé re se a rc h e rs to collect soil
a n d leaf sam p les in th e ir p lan tatio n s. They seem ed satisfied. O nce th e
re se a rc h e rs who are abro ad for a while have re tu rn e d , th is laboratory
should be able to w ork a t a norm al rate (1 000 to 2 000 sam p les per
year) on the b a sis of signed (and paid) co n tracts.
F u n g ic i d e s
Two com m on d iseases require control : Corticium salmonicolor (on
branches) a n d Phyptophtora palim vom (on th e tap p in g panel).
Corticium salmonicolor
B ordeaux m ixture (C uS 04 a n d lime) w as the only s u b s ta n c e u sed
u n til now. Things have changed. A lthough th ere is a certain a m o u n t of
reticence h ere a n d there to a b a n d o n B ordeaux m ixture, th e g rad u al
change to validam ycin is accelerating.
O rders in 1994 totalled 90.7 to n n es of C u S 0 4 a n d 398 .5 to n n e s of
lime (these figures were far from th e re q u ire m n ts a t th e tim e : WB
e stim a te s show ed th a t th e p la n te rs could have req u ested u p to 324
to n n e s of C u S 0 4 a n d 1,847 to n n e s of lime, i.e. m ore th a n four tim es
the initial quantities) a n d fell to 15 to n n e s of C u S 0 4 a n d 70 to n n e s of
lime in 1995.
In c o n tra st, re q u e s ts for th e s u b s titu te validam ycin
increased from 13,300 litres in 1994 (received a n d used) to 62,600 litre s
in 1995 (not yet delivered).
It is tru e th a t tre a tm e n t of Corticium w ith validam ycin does n ot
required th e scrap in g of th e affected p a rts of d iseased tre e s a s is
needed w ith B ordeaux m ixture for a re s u lt th a t is a t least a s good
since all the p in k color d isa p p e a rs after tre a tm e n t. This is th e only
criterion available for ju d g in g the effectiveness of th e p ro d u c t a s
p la n te rs do n o t ad d a dye to th e p ro d u ct w h ereas w ith B ordeaux
m ixture the w hite of th e lime is clearly visible on th e
tru n c k s a n d
b ran ch es. Would it n o t be possible a t least to m a rk the tr u n k s ?
Two p ro d u c ts are proposed : one C hinese a n d th e o th er J a p a n e s e .
The J a p a n e s e p ro d u ct w as favoured a s it is m ore active b u t the
co n tract w as won by th e C hinese p ro d u ct a s the price w as
su b s ta n tia lly lower.
Plujtophtora palmivora
T reatm en ts for black stripe disease a re know n well by all the
p lan ters. Difolatan, an tim ucyin a n d sim ilar p ro d u c ts are forbidden.
"Ridomil", a p ro d u c t b ased on m etalaxyl-m ancozeb, is the a u th o rized
pro d u ct used.
The 1994 o rder for "Ridomil" w as 13,262 kg (received a n d used).
The 1995 order is for 18,876 kg (not yet received).
The observation for validam ycin also applies : no dye is m ixed into
the p ro d u ct to m a rk th e b a rk to m onitor applications a s the tapping cu t
d escends. The only criterion show ing sy stem atic tre a tm e n t is th e
ab sen ce of black stripe. This is in fact difficult to observe.
S t i m u l a n t
Stim ulation trials were perform ed before WB intervention b u t a t
very c a u tio u s levels.
With WB su p p o rt, stim u latio n is now sta rtin g to be u se d a s a
no rm al exploitation technique. The ru les laid down are still very light
b u t take clones into acc o u n t (some of w hich sh o u ld be stim u lated a n d
o th e rs not), a n d the age of th e trees (stim ulation generally s ta r t s 6
y e a rs after th e opening of th e
trees
for tapping).
S tim u lan t
co n cen tratio n is also m odulated. As tapping is norm ally S / 2 D /3 D /4 ,
stim u latio n is possible a n d som e clones m u s t be stim u lated .
O rders totalled 2 3 1,600 litres of e th ep h o n in 1994 (of a potential
of 328,000 litres according to WB) a n d 226,000 litres in 1995. However,
alth o u g h the 1994 o rder w as received a n d u sed , th ere is still no sign of
the 1995 order.
Individual c a se s vary. In 1994, som e e s ta te s s u c h a s P hu Rieng,
Loc Ninh a n d Dong Phu took th e ir entire re q u ire m e n ts according to
W B .O thers took n o th in g (Dau Tieng). The rem ain in g e s ta te s took only
a p a rt of the stim u la n t proposed by the WB.
The sam e kind of contradiction is observed in 1995 (order n ot
delivered) : som e e s ta te s are convinced of the ad v an tag es of
stim u latio n a n d have req u ested m ore th a n in 1994 (Dau Tieng took
noth in g last y e a r a n d is m aking a sm all effort w ith 1000 litres a n d
Dong Nai h a s a sk ed for m ore th a n its share).
Some e s ta te s are tak in g less th a n la s t y e a r (Dong Phu, Loe
Ninh, Binh Long a n d Tay Ninh). Finally, betw een th e two extrem es,
som e e s ta te s have repeated th e ir 1994 o rd ers (Phuoc Hoa a n d Phu
Rieng). P lan ters are h e s ita n t a b o u t th e line to take, to say th e least.
Appreciable in c re a se s in p roduction have n ev erth eless been
observed. G ains have been of 20% to 30% , w hich carries no risk of
e x h a u stin g th e trees, especially if th e latex diag n o sis is u sed . This is
the m o st reliable way of achieving optim u m pro d u ctio n in th e context
of th is production.
A laboratory in Laikhé is especially equipped (with a contrib u tio n
by the WB) for th e purpose. Trials have been carried o u t on e s ta te s
w here p la n te rs say th a t they agree to co n tin u e to w ork w ith Laikhé an d
sign a co n tract. Tapping inten sity is very low (S /2 D /3 D /4) an d
stim ulation c a n n o t be refused a s long a s p re c a u tio n s are ta k e n to
avoid over-intensive or u n d er-in ten siv e tap p in g both of w hich lead to
p ro d u ctio n losses.
Even if th e latex diagnosis (L.D.) only prevents, on 10 % of the
area, 5% of th e loss (50 k g / h a of ru b b e r in yields a t 1 to n n e /h a ) for
eith er of th e re a s o n s above, th e laboratory will pay for itself. One
sam ple p er 25 h a would resu lt in a "gain" of 25 x 5 0 kg = 1250 kg of
ru b b er, the 10% on w hich is $US 125. This should be com pared to
$US 20 form ing th e cost of th e an aly sis enabling th e saving.
It is tru e th a t it is difficult to rely on the laboratory while sevices
it provides a re unreliable, if only b ecau se it is u n d erstaffed a n d th e
services ren dered are hardly covered by paym ent.
C o n c l u s i o n s
As a whole,
th e p la n te rs are playing th e gam e honestly. The
tech n iq u es proposed for tre a tm e n t of Imperata, Corticium a n d Phytophtora
were adopted rapidly. There is no need for en co u rag em en t to u se of
fertiliser a s they take th e m axim um each tim e. However, u se of
fertiliser should be backed u p by soil a n d leaf an aly ses. It is hoped
th a t stim u latio n will soon be considered to be a norm al ex p lo itatio n
tech n iq u e to be m a ste re d w ith th e help of latex diagnosis.
Annex
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Annex
Plantation mission notes
Dong Nai
Laikhe
Dau Tieng
Dong Phu
Binh Long
Ba Ria
Tay Ninh
Loc Ninh
Tan Bien
Phuoc Hoa
Phu Rieng
Dong Nai
Date : 1 August 1995
Welcoming personages :
MM. Nguyen Tuan Hung
Chief of Technical Sevices
Engineer
Chief of Accounting and Financial Services
Assistant Director of the Company.
Phan Ngoc Tuan
Nguyen Van Minh
Tran Van Khiem
Glyphosate :
The orders were small (1994 : 900 I -1995 : 900 I, against 24 000 I)
and there was not old stock, because it is the first time that they try this
treatment by hand; it must be 10 times more to cover all the
requirements (there are 13 plantations in this group that occupies
more than 40 000 ha). All the orders placed were delivered.
It is a fact that there is some imperata, which is not a crucial problem
for the Direction , Nevertheless, one must place a larger order for
1996, because there are some spots of imperata here and there.
There were 70 individual sprayers distributed on the Dong Nai Group.
For the little number utilised (the greatest part is in the ware-house
and couid be distributed to other plantations), these sprayers work, but
particularly if it is a matter of a small imperata (or newly cut down),
because with a high imperata, the knapsack (getting pressure manually)
works better and cost cheaper (and also is a local product).
A parcel of very young culture, treated with glyphosate, was visited. It
is exact that the product kills the imperata. But when it is already
there, and not when it appears somewhere after the treatment (it is a
systemic one). One must treat again.
Fertilisation : On the contrary, the fertilisers orders were maximum, and there are
stocks in hand. The situation at 30 June is :
The part of fertilisers from WB was utilised ; they work to day with the
stock in hand.
The WB rule (all spreadings must be limited to young cultures + 1
year) was respected . There are 2 spreadings every year, one at the
beginning, the other at the end of the raining season. The dosages pay a
great attention to the nature of soils (gray soil, red soil). Every
spreading is effected in mixture. Fertilisers are only used for heveas,
not for the intercrops (maïs, rice or other crops). The spreads are
effected in the very young age on the line, vertically under the crown,
though there are or not intrecrops ; as soon as the intercrops are not
possible (the hevea crown are more or less formed), the spreading can
be made in the interlines.
* The plantation Group of Dong Nai was divided in two : Dong Nai and Ba Ria.
urea
potash
rockphosphate
2367 T (+ stock in haud 482 T)
913 T (+ stock in hand 425 T)
2331 T (+ stock in hand 712 T)
In the same preceding parcels (cultures about one year old), in condition
to scratch a little the soil surface, the fertlisers are visible at the plants
foot.
The question is the use of Laikhe Laboratory for ordering fertilisers. It
is desirable that the fertilisers recommandation will be, for the futur,
linked to analysis of soils (generally speaking) and leaves (from the
formation of crown) effected by an specialised organism, certainly
Laikhe (for the beginning). A meeting was organised last month at Don
Nai to examine the question with the two parties (institute - planters).
In a first step, one can at the least -because there are two types of soil
(red soil and gray soil) and 3 main clones (GT 1, RRIM 600 and PB
235) in the young cultures- ask Laikhe to control and somewhat adjust
the fertiliser requirements. Afterward, it would be necessary to put in
place, on the plantation, laboratories for the analysis (more or less
connected for the circumstance). For exemple, the Dong Nai / Ba Ria has
a sufficient dimension to justify the creation of a laboratory for the
analysis requirement of soil and leaves. But for those questions, there
are previously many training problem to be settled.
Fungicides :
Corticium s a lm o n ico lo r :
There is a lot of Pink disease in Dong Nai. For Bordeaux mixture, there
was a small order for 4 T of CuS04, but no lime. To day they prefer
validamycine, of which 1800 I (1994) were delivered from Chinese
source, and 6000 I (1995) ordered to Japan (better quality). The
application of the treatment is effected without scraching, which
simplifies considerably the work, and directly with a pole from the
ground. The new cases observed are treated with a product coming from
China, as for the treatment of old trees affected by the disease, the
Japonese product, more efficient, would be used. The treatment with
validamycine is easy and economical. The choice is resolutely made in
favour of validamycine.
Phytophtora palm ivora :
