CURRENT RESEARCH ACTIVITIES AND THE DEVELOPMENT OF GOOD AGRICULTURAL PRACTICE (GAP) FOR PITAYA IN VIET NAM 

Nguyen Van Hoa,PhD.

Southern Horticultural Research Institute (SOFRI),

hoappd@hcm.vnn.vn & hoavn2003@gmail.com,

Longdinh, Chauthanh, Tiengiang, Vietnam 

1. INTRODUCTION

 

      In Vietnam, at present, the area for dragon fruit is about 13,500 ha with the production of about 211,000 tones and the average area per household is 0.5 – 1 ha (Nguyen Minh Chau, 2007). Producers of dragon fruit have seen prices for their fruit decline by about 60% since 2000 since the product mainly sell to local consumption or neighbour countries. Returns from dragon fruit could be significantly improved if small growers and exporters can gain access to new high value markets in Europe and North America. However, the Vietnamese exporters will need to find alternative markets for their products. High-value markets of Japan, Europe and North America have been non-receptive to Vietnamese dragon fruit due to perceptions of poor quality and lack of legal and food safety accountability. So many research works need to be done for improve the quality and production of dragon fruit. Over the past 10 years, many studies have been carried out on many disciplines such as plant protection, cultural practices, GAP developing, etc. In this paper we present some of the achievements from these researches.  

2. RESEARCH CARRY OUT BY SOFRI AND ITS RESULTS

1. Development of new varieties 
   

 

      

With the support from CIRAD (France), two new varieties (red and yellow pitaya) have been introduced to SOFRI since 1995. The red pitaya has good characteristics as more ability in flowering and less effect by light, good quality and beautiful red color. However, the fruit setting is poor, small size fruit with not good looking sharp.

      

From 1997, we made many crosses between red pitaya variety from Colombia and white flesh variety from Vietnam for better improvement in yield and quality of red dragon fruit. By the year 2000, we had 188 hybrids, which have been tested for desired characteristics and acclimatization at SOFRI campus and by the year 2002, the 12 potential hybrids have been tried at 3 different locations for acclimatization and then in the year 2005, one hybrid has been recognized by the Ministry of Agriculture and Rural Development.

      

 At present, we emphasize more in creating new varieties for pitaya from our collection of domestic and introduced varieties/clones. The collection includes varieties: (1) big fruit with green peel, small seeds but low yield; (2) red peel from ThaiLand, Taiwan, Réunion- France, USA; (3) purple flesh and yellow peel varieties from USA.  

2. Cultural practice studies

      

Through the years, many technical practices have been improved such as

changing from

alive

tree to ximent frame for pitaya to climb on,

density of the trees in or

c

hard,

nutrient from inorganic

fertilizers

to organic

matter

or manure

for better quality

,

training

and pruning for

distribution of the canopy

, etc

.

But the best practice is

the

induci

ng flower

technique

.

      

Inducing flowers in off season

      

There

some techniques for inducing of pitaya flowers include chemicals

’

treatment and light enhancement. Of them, the

light technique shown better results

with less side effects, so it is more applicabl

e.

Pitaya is a long day trees, it flowers only on the long day season. Base on this character, we carried many experiments to standardize the method for inducing of flower on pitaya.

      

Source of light

      

There are two sources of

electricity can be used for li

ght, one from national power and one from generator for those who have not had national electricity network. The first one is sustainable but not enough for light in large scale during the evening time, the second can be used only for the

60 Watt

bulb inst

ead of

75 Watt

bulb, which is very much effect on the quality of flowering

. 

      

Type of bulb for inducing light

      

As above, the

75 Watt

bulb has better effect on flower inducing, however, incase no national electricity, the second option can be used.

      

The bulbs

line is hanging between two rows of pitaya at the high of

0.

7 m t

o

1.

2m

or we can keep one bulb in the central of four pitaya trees, the light should distribute in all direction of the tree

.

      

Time for lighting

      

The result from studies showed that the time

for lighting from

8-10

PM and continuing in

15

to

20

nights is sufficient for flowering. However, the result of flower

ing also depends

on the conditions such as

season of the year, rain, storm, typhoon, the conditions of the soil, the tree

’

s health, etc.

      

After stop lighting of 3 to

5

days

,

the flower bud will appear

, after that

it needs

20-21

to develop flower and 3 days for flower open and fertilization and then the fruit develop within

25

to

28

to mature

.

So total time for one fruiting c

y

cle is about

50 to 52 days

. Beside that this duration also depends on the condition of weather and season of the year

.

Flower induced process using light:

Light

    

    Stop light  

     Flower

Budding

  

   Flower       Fruit setting

  

 

    

Harvest

15-17

nights

   3-5

days

          21

days

               3

days

              28-30

days

Sensitive time for flower

    

Flower develop and fertility

   

Fruit development

Formation of flower

 

      (

average

of

24

days

)

 

           (

average of 28-30 days

)

      

Average of 22

days, nights

                        

Average of

52-54

days

      

To improve the quality, good looking appearance and especially for the firm and green bracts, the foliar fertilizers such as

Growmore, Miraclegrowth

, should be used, plus plant growth regulators

as

GA

₃

(Progibb).

3. Plant Protection studies

 

      

The survey has been carried out

to know the status of the pests and diseases and to do research to find out the solution for major insect pests and diseases. 

2.3.1. For disease matter

      

The result shown that ther

e

were eight

different diseases attacked pitaya tree in Vietnam, the list as below: 

Table 1. List of diseases attacked pitaya tree at Longan, Tiengiang and

Binhthuan province (SOFRI, 2005)

                                                                                                   

No	Disease	Causal organism	Attacked part	Time of record	Popular
1	Anthracnose	Collectotrichum gloeosporioides	Fruit, Flower, branch	Rainy seasion	+++
2	Fruit rot	Fusarium sp.	Fruit	Fruit Ripening	++
3	Branch rot	Fusarium sp., Xanthomonas	Branch	Late dry and early of rainy season	++
4	Like sunburn	Macssonia agaves syd, sphaceloma sp.	Branch	Late dry and early of rainy seasion	++
5	Brown spot	Glocosporium avages	Branch	Year round	+
6	Black spot	Ascochyta sp.	Fruit and branch		+
7	Melanoes	Capnodium sp.	Branch, fruit		+++
8	Scab	Unidentify	Branch		++

      

Note: + Low,   ++ Medium,   +++ More popular 


      

Of them, anthracnose is the most serious disease, which caused much damage to the trees and the yield both pre and post – harvest. SOFRI had put more emphasize on study this disease.  


Anthracnose disease and it measurement

- Characters of the disease

      

The disease caused by Colletotrichum gloeosporioides, is an important disease not only on pitaya but also on many other fruit and vegetable crops such as mango, durian, red pepper, etc. The disease causes damage to fruit which make lost yield, quality of fruit and reduce the price. This disease is more dominant during the rainy season, the fungus attacks to stem, branch, flower bud and fruit, especially post harvest.

- Management strategy

+ Cultural practices

• Wind break : The tall tree should be planted in front direction of the wind, that makes the orchards away from the source of inoculums.
• Tree frame: Replace of the alive tree by the ximen frame for the pitaya to climb on, which can reduce the disease transfer from the frame trees. The ximent pillar should have 2 -2.5 m high and diameter of 12-15 cm, the base of the pillar should keep under the soil surface of 50cm depth.
• Balance nutrient for the trees: The inorganic should be control at suitable levels and at right time, more organic fertilizer should be used to improve quality of the fruit.
• Water management: In the area of serious disease, not to used water in the pond to spray over the canopy of the tree.
 


+ Physical treatment

• At young stage: Training and pruning of the trees to help the branches distribution in 4 direction of the tree, which help the tree get more light, better photosynthesis, reduction of disease of course.
• Fruit bearing trees: Cut all the diseased branches, soil touching branches.
 


+ Biological control

• Apply more organic manure plus antagonist fungi such as Trichoderma, which help in decompose the manure and kill the pathogen present on the fall branches in the soil surface.
• Apply Salicylic acid to help the tree stimulate resistance to disease (15 days before harvesting).
• Bag the fruit at 14 – 15 days before harvesting to reduce diseased infection and fruit fly attack.

+ Chemical treatment

      In the serious infected orchards, the chemical should be used to reduce the inoculums, the chemicals used as follow:

• Apply copper chemical after harvesting and after pruning.
• Use Propineb or Difenoconazole to apply.
 


+ Post harvest treatment

   The fruit after harvest can be kept in warm water at 53^oC for 10 min. 


2.3.2. For insect pests problem

         

The survey shown that there were some serious pest as beetle, ant, mealy bud and fruit fly attacked pitaya trees. Of them, the beetle is better to catch by hand, mealy bud can be control by diluted liquid NaOH plus soft chemical.

         

The most important pest is fruit fly, there are two species infected to pitaya fruit as Bactrocera dorsalis and B. correcta. To minimize this problem, SOFRI has developed protein bait called SOFRI PROTEIN, which made from beer waste, both male and female fruit fly need protein for developing of egg and sperm, they come to eat SOFRI PROTEIN, they also consume insecticide, the best insecticide used is fipronil. Recently, we develop the trap to kill fly by electricity, we put Methyl eugenol and protein in the central of the trap and the keep the power on, when they come for bait and pheromone they will be killed by electricity.

         

In pitaya, we identified two main ant species, one is

red ant

: Solenopsis geminata Fabricius and the other is Cardiocondyla wroughtoni. Both the two caused harm to pitaya fruit by bidden on the fruit skin, which make the wound for disease to attack the fruit and also cause scab on the fruit skin, which lead to bad looking of the fruit and the the price is badly reduced. To control this, we develop the bait called SOFRI – TRU KIEN (SOFRI – kill ant), which can kill both the soldier ants and the queen also.  

4. Post – harvest studies

      

The result from study by Hoa et al, 2006

shown that

the pitaya can be treat at 46.5

^o

C for 20 min

in vapor heat treatment unit

(Sure-Unit)(made by HortRese

arch)

to kill fruit fly and fungal diseased with

very less or

no effect to the fruit skill and quality. 
 

3. DEVELOPMENT OF GAP ON PITAYA IN VIETNAM

         Since 2005, the Good Agricultural Practice has been applied to pitaya industry zone and the first EUREPGAP certification given to Vietnamese fruit industry is to pitaya for the cooperative named HamMinh, with 11 ha in 2006, following that another 7 ha farm got certificate in 2007 and then late 2007 one other group of farmers of 80 ha got EUREPGAP certificate. To the above achievement, the AusAID project from Australia fund to Vietnamese institution and dragon fruit industry collaborate to USA project to help farmers to implement GAP. SOFRI play main role in these projects. The project has established a private sector working pilot of exporter/packer and supplying dragon fruit growers in which the European high value market driven standards of BRC at the packer and EUREPGAP at the farmer level have been implemented. And the results coming with:

   1. Field farmers’ benchmarking survey and the result delivered as a PowerPoint presentation to SOFRI personnel, also packers, farmers, MARD and DARD personnel of Binh Thuan in 2007.
   2. Selection of a packer/exporter and farmer group for the Project Pilot were confirmed and formalised. Training of the Pilot members for improvement towards British Retailers Consortium: Global Standard – Food (BRC) for the packer and EUREPGAP for the farmers were carried out to enable them to reach compliance in all areas. The pilots both for field production and packhouse were implemented and all the corrections have been done and then the Certification for EUREPGAP with 80 ha of dragon fruit production has been achieved while the packhouse are being waiting for BRC certification.
   3. The dragon fruit quality manuals for the farmer and packer were developed in a way that closely related to the current practices, included appropriate improvements to enable the farmer and packer to meet compliance with the EUREPGAP and BRC standards, and are user friendly.
   4. The national personnel capacity building within the project team and in the private sector has seen practical GAP proficiency developed to a high level which will ensure the continued development of the pilot and the subsequent distribution of the model to many more small-holder fruit crop producers.
   5. The certified products has been sent to European market and the US market are ready to import pitaya product when it scan under radiation.
   6. Now we are extending the area of the GAP production to other area in the year 2008 (30 ha in Long an, 70 ha in Tiengiang and 150 ha in Binhthuan provinces.
   4. References 
       
      
    
   

   DIEN, L.Q., 2006. Integrated management of insect pests in Dragon fruit. Proceeding of Dragon fruit workshop. Held on 6 Sep. 2006 at Binhthuan

   HOA T. T., CLARK C. J., WADDELL B. C. and WOOLF A. B.2006. Postharvest quality of Dragon fruit (Hylocereus undatus) following disinfesting hot air treatments. Elsevier Science, 2006, vol. 41, n^o1, pp. 62-69 [8 page(s) (article)] (10 ref.).

   HOA, N.V. 2006. Integrated Disease management for Dragon fruit, Proceeding of Dragon fruit workshop. Held on 6 Sep. 2006 at Binhthuan

   HOA, N.V., HOANG, N.H., JOHN M.C. AND CHAU, N.M. 2008. Developing GAP systems for dragon fruit producers and exporters in Binh Thuan and Tien Giang provinces. Proceeding of Dragon fruit workshop. Held on 21 July. 2008 at Binhthuan.

   HOANG, N.H. 2005. Some cultural practices for Dragon fruit trees (Hylocereus undatus), Proceeding of Dragon fruit workshop. Held on 6 Sep. 2006.

   NGUYEN MINH CHAU, 2007. Present scenario, market trends of the tropical and subtropical fruit industry in vietnam, TFNet Report, 2007.

   YEN, T.T.O, 2006. Dragon fruit selection and breeding status in Vietnam, Proceeding of Dragon fruit workshop. Held on 6 Sep. 2006 at Binhthuan