Jackfruit Tips

  • I met Mr. Zahar who works at the Agricultural Park in Kuantan, Malaysia and has a fruit tree nursery. With Jackfruit he prepares the rootstock in the morning and waits 3 hours before he joins the new scion wood to the rootstock. Remove all the leaves off the rootstock. It is wedge grafted when the buds start shooting. One day before they graft, he will make some scars on the trunk of the rootstock. His sharpening tool is a warm stone, quite chalky - it comes off white in your fingers. Ref: Sheryl Backhouse
  • You can root by cuttings and also by airlayers. Ariel from Israel demonstrated in Fiji 27 years ago how to prepare apical cuttings of all Artocarpus species including Marang, breadfruit, Jacks etc and showed how to use sandy soil to prevent decay and how to mist and halve the leaves. As an initial step, he recommended to hold half of the total cutting size 20-30 cms long in water for 2-3 days as to remove the latex and give a chance to various rooting nodes to swell.  With bottom heat of 30 celsius and mist, the summer cuttings of Jacks rooted within 60 days.
  • Grafting Jackfruit  Some members have found it difficult to graft Jackfruit so I’ve consulted the various books and emailed various people and this is what I have found:
    I have Richard Campbell & Noris Ledesma’s book The Exotic Jackfruit and emailed Richard to obtain permission to write the whole chapter on grafting into our newsletter and when he wrote back he said that they now use a new method: “We now graft jackfruit when the seedlings are less than 2 months from germination and we use all green scion material with about 5 to 7 leaves remaining (cut in half). The scion is just ready to expand a new leaf, in other words, highly active. We put the whole grafted plant in a plastic bag in indirect light and remove after they have expanded a whole new leaf. Temperatures of 16 – 21 C average are best.  Another grafter says: “they flush intermittently all year - less in the winter. I like to graft them after the daytime temperatures have come up to about 29 C. I have found that when I collect fresh budwood, the grafts take but if the budwood gets shipped (even 2nd day air) none of it lives.”
    I also brought back from India N. Haq’s book on Jackfruit and it says there are two methods:
    Veneer grafting involves collection of a 4-5 month old terminal shoot from a selected mother tree and grafting it onto a one year old rootstock.
    Epicotyl grafting is done on a 20-25 day old seedling with slightly thicker stock and 4-5 leaves. Rootstocks selected are headed back to 8-10cm. The exuded latex is removed with tissue paper. A 5cm slit is made vertically on the rootstock. Scions with a growing bud present are prepared by making a wedge cut on both sides. The scion stick is inserted into the slit made in the rootstock and tied with polythene tape.  Ref:  Sheryl Backhouse
  • Non fruiting trees   I visited one of our member’s properties and although nearly all of the trees looked great and grew well, a lot of them produced very few fruit. Some such as the Black Sapote and Grumichama had heavy crops; I was asked if I knew the solution. I have been told many times that zinc is critical for cell division and flowering, but although it might help I didn’t believe this was the main issue. I did notice that the Jackfruit were malformed which is an indication of poor pollination. I remember that Peter Young had told us all many years ago that boron increased seed set, so I suggested that increasing the amount available to the plants by ground application or by foliar spraying should be effective. Boron is toxic to plants at quite low amounts so its application needs to be carefully controlled. The soil application rate using Borax is about 2 grams per square metre. Custard apples when deficient can be given up to 5 g/m2 , though care must be taken to ensure that the spreading is even. Below are quotes from Plant Nutrient Disorders 2 Tropical Fruit and Nut Crops, which we used to have in the library.
    “The fruit of boron-deficient Pawpaw are deformed and bumpy due to the irregular fertilisation and development of seeds within the fruit. Ripening is uneven and the developing fruit secrete pinkish white to brown latex. Heavy premature shedding of deficient male tree flowers and impaired pollen tube development can lead to poor set in the fruit-bearing female trees.”
    “Deficient avocado trees produce small misshapen fruit, usually twisted to one side giving them a dumpy, lop-sided and bulbous shape. An indented blemish sometimes appears on the concave side of these fruit.”  Ref:  George Allen
  • I tried propagating cuttings of Arto. species in Fiji and Arto. hetero. in Israel and it works but it takes a long time as the roots break easily so each cutting should be placed in a small pot and not in a rooting bed. I used apical cuttings only of 15-20 cms long leaving a few cut-halved leaves with bottom heat of 30 celsius.   Ref: Ariel in Israel
  • Unfortunately Jackfruit in my experience are as bad as apples for not resembling the parents. I fruited 32 seedlings of a particularly nice red-fleshed one I got in Hawaii and the 31st to fruit was the only red one - but a real winner. Number 32 has its first fruit hanging right now - I'll know in a couple of months what it is like. So far, out of 32, only 2 are worth propagating.   Ref: Stephen Brady
  • Leaf Shapes - Young jackfruits can have rounded or lobed leaves but when they are mature the leaves are more uniformly elongated.
  • Guinness Book of Records - A Black Gold grown in Hawaii weighed in at just over 34kgs.
  • Ross Dickson from the Fraser Coast Sub-Tropical Fruit Club in Maryborough says:
    Effort is required to process the seeds and this is what I found to be the best method. Remember the outer husk of the seed has to be removed but NOT the brown inner skin which is edible. I allow the fresh seeds to dry overnight after rinsing and this makes the outer husk clearly visible but mainly so that you can then grip the previously very slippery seed without risk of cutting your fingers when processing. I first cut my seed lengthways and this is more difficult but gives a much better result when peeling. Simply cutting across the seed in the middle makes peeling off the outer skin slow and laborious. Boil in salty water for about 20 to 25 minutes. Take a few out and you will soon learn if they are cooked enough. Allow the nuts to cool and dry and this will clearly show the outer husk as separate and a different colour. A lot of the nuts will have lost their skin when cooking if cut lengthways and the remaining skins are easily removed by using a serrated edged steak knife to improve your grip on the outer skin. It doesn’t matter which side you cut from but you will find one side of the nut fairly flat and much easier to grip when cutting. The other side is very rounded and prone to move around risking a cut finger.
  • Several members purchased Kwai Muk trees from Kaspar Schnyder. For those unfamiliar with this tree, here’s a few facts. Kwai Muk (Artocarpus lingnanensis or A. hypargyrea) is closely related to Jackfruit. It is native to Southern China, where it grows above 150 metres altitude. It is a slow-growing, erect tree to 10 metres, with attractive long slender leaves. Its dark green foliage makes it an attractive landscaping tree. Kwai Muk produces small round fruits which have a velvety, yellow-brown skin, and orange to red flesh. The fruit may range from seedless to about 7 small seeds. These fruits are about 2.5 – 5 cm across (golf ball sized) and are acid to subacid and said to be refreshing and of excellent flavor. They can be eaten fresh when fully ripe, or can be dried, or preserved. The trees can be propagated from seed. In Queensland, the fruit ripens from February to April. Tiny yellow male and female flowers are produced on the same tree, the females in globular clusters about 1cm long. Two trees may be needed for good fruit production. It is similar to mango and jackfruit in cold hardiness, with mature trees being able to survive about -4°C. It is relatively wind hardy.