highly successful wedge grafting for rambutan

4

Proc. Fla. State Hort. Soc.

119: 2006.

Proc. Fla. State Hort. Soc

. 119:4-6. 2006.

HIGHLY SUCCESSFUL WEDGE GRAFTING FOR RAMBUTAN,LYCHEE, LONGAN, MANGOSTEEN AND OTHER FRUIT TREES

P

ANFILO

C. T

ABORA

1

*

AND

L

UIZ

A

TIENZA

2

1

EARTH UniversityMercedes de Guacimo, Limón, Costa Rica

2

University of the Philippines at Los BañosCollege, Laguna, Philippines

Additional index words. Nephelium lappaceum

,

Litchi chinensis

,

Dimocarpus longan

,

Garcinia mangostana

, cleft grafting

Abstract.

The wedge grafting technique is described in detailfor students, nursery growers and technologists. Formerlyconsidered as very difficult to accomplish and with poor re-sults, this technique is now yielding very high graft successbeyond 95% in rambutans, lychees, longans and other fruittrees in Costa Rica, and 100% in mangosteens by beginnerssuch as the students at EARTH University in Costa Rica. Thistechnique, which has been pioneered in the Philippines, hasbecome a major boost for the rise of rambutan production andexports in Central America, and is on its way for applicationsin lychees, longans, avocados, mangos, mangosteens andothers. It is now used in Honduras, Guatemala, Costa Rica andBrazil for these crops.

Brunner (2002) had a cleft (or wedge) grafting successrate of 26% in nursery grown rambutans (

Nephelium lappace-um

) and 42% in the field in Puerto Rico. He, therefore, rec-ommended the use of approach grafting which, althoughcumbersome, had 88% success rate. Morton (1987) describedcleft grafting as “not-as-satisfactory” as the patch buddingwhich had over 80% success rate in Mindoro, Philippines (ifdone in May).

Wedge graft specifically offers greater stability than theother grafting techniques due to the instant full balance be-tween the stock and the scion. It also results in faster develop-ment of the plants to be ready for field planting much sooner.For the students it encourages skill, precision and extremecare that is desirable for horticulturists, and for the teachersit is a great demonstration of many principles in horticulture.It can also be done almost all year-round.

Materials and Methods

The wrapping materials used were the following: (a) longstretchable plastic strips which are thin and transparent, of 2cm width and 20 cm length for wrapping the scion stick, andanother shorter plastic strip of the same kind, but only 10 cmlong for holding and tying the graft union firmly, (b) stretch-able parafilm strips of the same dimensions as the longer plas-tic strips enough to wrap the graftsticks completely.

For the graftsticks of rambutan and the other fruit cropswe chose those shoot terminals with leaves that had maturedalready where developing buds could be seen clearly, an indi-cation that these are active buds and the graftwood is alsoactive. We cut them at the base of the previous flush growth

and obtained 2-3 graftsticks of about 10-12 cm length for ev-ery shoot terminal. We wrapped them with the plastic stripsexcept the 3 cm at the base (for the graft cuts) ensuring thatthe graftsticks were fully covered without having overlaps ofthe rims. At the tip a knot was done to fix the plastic wrap.With the parafilm wraps the knot was not necessary.

Stock plants were just about 8 to 9 months old from seedgermination (the previous year’s harvest) and not quite pencilsize, but already had a third flush of growth and were about 50cm tall. We also used materials which were older from the yearbefore last, had them cut back to 10-15 cm so that we could usethe newer shoots of about the same size as the recently germi-nated ones and also was in its third flush (Fig. 1A).

A cut below the youngest node of the previous flushgrowth eliminated the immature flush and exposed activelygrowing wood where a wedge or cleft was made by insertingthe knife longitudinally on the internode and then slicingdown at the middle about 2-3 cm long incision, simply by pull-ing down the knife. We then selected a graftstick slightly big-ger than the stock size and made a 2-3 cm V cut smoothly andwell balanced on both sides and which was immediately in-serted to the wedge (Fig. 1B). We used the shorter plastic towrap and firmly press the union cuts with a knot, making surethat the meristematic arcs that appeared on both sides of theV cut of the graftstick had touched the meristematic columnson both sides of the wedge incision of the stock (Fig. 1C).

Finally, a slender plastic bag 4 cm wide and 15 cm long wasput open side down to cover the graftstick and the union pro-viding a protective sheath as well as a type of incubator for thegraftstick and the graft union (Fig. 1D). Within 10 d, the budwould show a bulge and a green coloring indicating that thegraft union had taken place and encouraged bud develop-ment. In another 5 d, the leaves would be developing andsome 20 d from grafting the leaves would be filling up theplastic sheath, a time to remove the sheath (in the after-noon). By some 45 d the shoots would be mature sufficiently,the time to loosen the plastic strips. In the case of the parafilmthis was not necessary.

The teaching method included the theoretical discussionfor 1 h comparing different methods, the demonstration foranother hour that included nursery practices and then the dif-ferent steps in wedge grafting, and finally a 2-h assisted prac-tice where 25 students were assisted by the professor and 2assistants. Every student had four seedlings to graft for the 2-h period. Afterwards everyone had to check their grafts dur-ing the next 2 weeks. If there was anybody who felt not success-ful, he had to do another set of four immediately, because hehad to present at least 2 successful grafts in another 4 weeks.

Results and Discussion

Mastery of the students.

Over three years of work with 200college students, they have shown that they can master thetechnique very quickly with rambutan:

Percent of students with a successful graft at the firsttry = 85%

*Corresponding author; e-mail: ptabora@earth.ac.cr

PROOF

Proc. Fla. State Hort. Soc.

119: 2006. 5

Percent of students with successful grafts on a secondtry =100%

We also tried this on 45 non-college students in various work-shops and have had very good graft results:

Percent of trainees with a successful graft at the firsttry = 100%

Percent of graft success of the trainees on the first try= 65%

The students and graduates of EARTH University whohave mastered the grafting technique have gone into con-tracts to graft rambutans and have been able to show as muchas 95% success in such places as Brazil, Guatemala, Hondurasand Costa Rica.

Graft results.

In the case of mangosteens (

Garcinia mango-stana

), the rate of success has been 100% uniformly over thepast 5 years with as many as about 55 students and about 25non-college students.

In the case of mangos (

Mangifera indica

), there is no needfor wrapping the graftstick. The plastic sheath was enough

Fig. 1. A. mature state of graftstick. B. Materials for grafting. C. Topped-off seedling with the graftstick. D. Grafted rambutan with plastic sheath.