Best practice in durian nursery

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					               Practice in durian nursery in the Southern Viet Nam.
                   Nguyen Minh Chau, Huynh Van Tan, Huynh Van Thanh.
                           The Southern Fruit Research Institute,
                          Box 203, My tho, Tien Giang, Viet nam
                                 Email: MCH@hcm.vnn.vn


                                         Abstract
       Cho Lach district Ben Tre province in the MeKong Delta is well known for its
production of fruit tree saplings in the Southern part of Viet Nam. The Cho Lach people
produce more than 20 million citrus, durian, mango, mangosteen and rambutan saplings
annually.
       In general, the quality of the sapling is good, as the nurserymen are skillful and
experienced.
       Around 6 years ago, the traditional budding technique was replaced by the U-
grafting technique, which allows 4 to 5 times higher in the number of saplings produced per
budwood than the budding technique. The U-grafting technique is much easier to do than
budding technique.
       The U-grafting technique is applied for once rootstock sapling, while the cleft graft
technique is used for two-rootstock sapling. Saplings with two rootstocks grow faster than
the single rootstock saplings.
       It is important that more attention is paid to produce disease-free planting stock in
the future to prevent the spread of diseases. As the investigations showed a high percentage
of current planting stocks were susceptible to the Phytophthora disease, in potting mix, in
the grafting point of durian saplings. The application of fungicides showed very useful to
control the Phytophthora during the nursery stage.


Introduction
       Durian is considered as one of the important fruit crops in the southern part of Viet
Nam. It is grown up to higher than 900m of sea level to lowland in the Mekong Delta of
Viet Nam.
       Nursery practices of fruit trees are very important as they might carry the diseases
and insects to a new place. Hence, the nursery practices at Cho Lach, Ben Tre province
were studied on:


                                                                                               1
     -    Method of propagations
     -    Effect of one and two rootstocks on the growth of saplings in the nursery and at
          one year after planting
     -    Effect of some factors that are related to saplings quality


Materials and methods
1. Methods of propagation were investigated at the nurserymen in Cho Lach:
         - Marcotting method
         - Budding method
         - Grafting method: U-grafting and cleft- grafting.
2. The effects of one and two- rootstocks systems on the growth of durian saplings
3. Effect of some factors that related to the saplings quality were investigated from 10
nurseries
         - The components of potting mix and its relation to Phytophthora fungi were
         investigated.
         - The kinds of fungus presence in the nursery.
         - The effect of some factor like:
         Density of saplings in the nursery, fungicides, on the percentage of the pots having
Phytophthora fungi were recorded.
4. Ten nurserymen were surveyed, 200 potting mix samples were taken, and 100 saplings
were sampled for identification the presence of Phytophthora palmivora.
  . Phytophthora was isolated at SOFRI (Thanh, 2000,2001,2002) and identified at
  Cooperative Res. Centre for Tropical Plant Pathology (Andre, 2002,2001).
         -Duration of investigation: 1997-2002
         -Location of nurserymen involved in the survey: Cho Lach District, Ben Tre
Province.
  . t- test was used to analyze the data.


Results
1. Propagation methods
  Several vegetative propagation techniques for durian have been investigated: marcotting
(air layering), budding and grafting.




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Air layering
        - Healthy stem with length from 80 to 100 cm selected.
        - Girdling the stem to peel of the bark.
        - After of the bark was peeled, kept 2-3 weeks, wrapped with moist medium (water
       hyacinth roots) to initiate roots.
        - After 45-50 days, if the roots developed then the cutting can be done.
        - Keep the newly rooted saplings under the shade.
        - Success: 40- 50%
        - Good time to do marcotting Mar/Apr.
Budding
       Budding was practiced for a long time in Viet Nam. Around 6 years ago, it was
replaced by graft techniques. This is because, in budding the scion has to be selected and
taken very carefully and also because the budding technique is more difficult to do than the
grafting techniques.
       The steps in budding were as follows:
        - Rootstocks at the age of 18-24 months, 2.5-3cm in the diameter and healthy
       rootstocks were selected
        - Cut U-shape
        - The bud (1 eye) selected, and cut from 2.5 to 3 cm long
        - Inserted the bud (1 eye) into the rootstock
        - The budding graft was covered with coconut leaf
        - The graft wrapped with polyethylene, keep in the shade for 3 weeks, and then
       remove the polyethylene
        - The newly budding plants were kept under the shade
        - The best time for budding: Oct/Nov
        - Success from 50 to 70%.


Grafting techniques
       This method has been used widely since 6 years ago, as these techniques are much
easier to do than the budding technique. There are two kinds of grafting technique being
applied for durian.
        - U-grafting technique
        - Cleft grafting technique



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U-grafting technique
       The steps in U-grafting technique was as follows:
       - Rootstock at the age of 18-24 months old was selected
       - Its barks were cut like ∩, at 0,8-1cm wide, 2,5-3cm lengths
       - Cutting the mature budwood into 4-5 scions, each with one bud (1 eye) and 1/3 of
       leaf prepared Scion
       - Scion was inserted into the rootstock
       - Wrapping the scion and the rootstock
       - The grafted plant was covered with polyethylene bag
       - Kept under the shade (50% sunshine)
       The U-grafting technique being applied to produce the one-rootstock durian
saplings
       - Success percentage is around 90%
       - Good grafting time good in May/June.


Cleft grafting technique
       The cleft grafting technique widely used in Viet Nam to produce two- rootstocks
saplings of durian. The steps involved in cleft grafting technique were as follows:
       - Two-rootstocks at the age of 5-6 weeks old were grafted first
       - Then the top of united rootstock was cut, and then the central of the united
       rootstock was opened with a sharp blade so that the scion can be inserted into the
       rootstock
       - Scion was prepared like U-grafting technique. However, at the base of the scion,
       the cut was made V shape so that it can be fixed into the rootstock
       - Inserted the scion into the rootstock
       - Wrapping tidily the scion and the rootstock
       - Cover the grafted plant with polyethylene bag
       - Keep the grafted plant under the shade (50% sunshine)
       - The cleft grafting being applied to produce two-rootstock durian sapling – one
       family can produce 20,000 saplings by cleft grafting technique annually
       - Success percentage is around 80-90%
       - Best time to graft in May-June




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2. The effects of one and two rootstocks system on the growth of durian saplings
- Plant height and number of primary branches: after 9 months of grafting. The data showed
that saplings with two- rootstocks saplings recorded a significantly higher in plant height
and number of primary branch as compared with that in one- rootstock sapling (table 1).
                 Table1: Plant height and number of primary branches
                       Plant height (cm)                Primary branch (branch)
      No
              One- rootstock     Two- rootstock    One- rootstock    Two- rootstock
       1             70                 60                8                  4
       2             67                 61                7                  5
       3             67                 64                9                  4
       4             65                 60                8                  6
       5             64                 62                8                  4
       6             66                 58                8                  5
       7             64                 59                9                  5
       8             75                 54                6                  4
       9             61                 60                7                  4
      10             62                 63                9                  4
     Average        67,1                60,1             7,9              4,5
                                      *                                  **
      t- test                 3,6228                              9,1599

- Plant height after one year of planting of one- rootstock and two-rootstocks saplings:
The data showed that the sapling of two-rootstock sapling recorded a significant higher in
plant height as compared with that in the one-rootstock saplings (table 2).
             Table 2: Plant height after 12 months of planting.
                                               Plant height (cm)
               No.
                                  One- rootstock               Two- rootstocks
                1                      183                          160
                2                      185                          157
                3                      187                          161
                4                      184                          162
                5                      186                          157
                6                      188                          156
                7                      190                          152
                8                      190                          154
                9                      188                          150
               10                      190                          150
             Average                  187,1                         155,9
                                                            **
              t- test                              15,0343



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       The two-rootstock saplings were not only need less time to produce (12-14 months)
than the one-rootstock saplings (2 years), but also grew faster in the nursery stage and at
one year after plantings. The price of two- rootstocks saplings also cheaper than one-
rootstock saplings
       SOFRI recommends farmers to use the two-rootstock saplings.
3. Effects of some factors that related to the saplings quality (in relation to
Phytophthora disease).
 Components of potting mix and its relation to Phytophthora:
 + Two kinds of potting mix were noted as follows:
*Burned rice husk+ compost rice husk+ soil dried+ some bat manure (3: 1: 1)
*Burned rice husk+ compost rice husk+ soil dried+ Coconut fibre+ some bat manure
(3: 1: 1: 1)
 + The potting components were taken for identification the presence of Phytophthora-
palmivora, the data recorded showed that:
   . Burned rice husk: No Phytophthora palmivora.
   . Compost rice husk: 5% samples having found Phytophthora palmivora.
   . Dried soil: No Phytophthora palmivora found.
   . Bat manure: No Phytophthora palmivora
   . Coconut fibre: 20% samples found Phytophthora palmivora.
     Hence, Coconut fibre and compost rice husk should not be used as potting mix,
because they might have Phytophtora palmivora.


* Effect of with and without fungicides application on the percentage of disease
saplings.
            . Hexaconazol (Anvil 5SC) 40ml/8 litres or Copper oxychlorid 85% (CoC 85)
25g/8 litres or Fosetyl- Aluminium (Aliette 80 WP) 20g/8 litres or Metalaxyl (Ridomyl
MZ- 72 WP) 30g/8 litres were used as alternative, at 15 days interval. 200 ml Fosetyl-
Aluminium (Aliette 80 WP) 20g/8 litres was also irrigated into the pot, when of putting the
rootstock into the pot.
            . Rhizoctonia solani, Phomopsis sp., Collectotrichum ziberthinum and
Phytophthora palmivora were recorded in the pots. However, the percentage of disease
saplings was higher in without fungicide application pots as compared with pots with
irrigation and spray fungicides. (Table3)



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                Table 3: Effect of with and without fungicides applications
                             on the percentage of disease sapling


                                                   Percentage of disease sapling (%)
No                   Fungi
                                               With fungicides        Without fungicide
1    Collectotrichum ziberthinum                     1,5                      7,5
2    Phomopsis sp.                                   7,5                     35.0
3    Rhizoctonia solani                              1,5                     32,5
4    Phytophthora palmivora                          4,0                     55,0
 Note: Average from10 nurserymen


        The data showed that the applications of different fungicides as sprays at 15 days
interval irrigation into the pots were necessary to control fungi.
    All the nurserymen applied the fungicides at 15-day intervals after grafting had
performed
* Effect of saplings density in the nursery on the percentage of pots with
Phytophthora.
                    Table 4: Effect of saplings density in the nursery
                           on the percentage of pot having Phytophthora


           No                Density         Percentage of pot found Phytophthora
                                                                (%)
            1           16 saplings/m2                          3,5
            2           25 saplings/m2                          7,5


      The data showed that high density had a higher percentage of pots found
Phytophthora palmivora as compared with low density (table 4).
      * The samples at the grafting points of one rootstock and two rootstock saplings
were taken for identification of Phytophthora palmivora.
       It was recorded that the Phytophthora- palmivora also presence at the grafting point
(5% of saplings).
    Hence, the scion and scion branch might also be the sources of Phytophthora disease




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Conclusion
   •   The U-grafting technique being used for one- rootstock sapling production while the
       cleft grafting technique being used for two-rootstock saplings production.
   •   The two-rootstock saplings grew faster than the one-rootstock saplings.
   •   5-10% saplings in the nursery stage were susceptible to Phytophthora palmivora,
       depend on the application of fungicides, the saplings density in the nursery, the
       components of potting mix, the source of scions.
Recommendations




References
Erwin, D. C. and Ribeiro, O. K., 1996. Phytophthora Diseases Worwide. University of
        California, American.
Guest, D.I., 1998. Management of Phytophthora disease of durian 3e. Integrated disease
        management. In: Phytophthora disease of durian, 1998. ACIAR project PHT
        95/134. Workshop no.1.Project planning 6th- 12th December1998. Page 110- 112.
Lim T.K., 1990. Durian diseases and disorders, Tropical Press Co. Ltd. Kuala Lumpur,
        Malaysia.
Lim, T.K., Poffley. M. and Bowman, L.,1992. New grafting techniques for exotic fruit
        trees. Technical bulletin No. 194. Department of Primary industry and fisheries.
        Northern Territory of Australia.
Subhadrabandhu, S. and Ketsa, S., 2001. Durian King of Tropical Fruit. CABI, Daphane
        Brasell Associates Ltd, New Zealand.




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