No Chill Stone Fruit for Hawaii

The propagation and distribution of Prunus mume to the project collaborators from 300- to 3,000-foot elevations showed mixed results. One collaborator's tree died. The other six had mixed growth rates, with one exceeding the normal rate of about two meters per year. None of the trees have flowered yet but are expected to in the next year or two. The collaborators have expressed their desire to keep monitoring the trees and report back to the fruit growers group. They have also mulched the trees to promote root shoots for propagation in order to use these as rootstock for other Prunus.

The project coordinator has continued to propagate the Prunus mume as well as collect different varieties of peaches and plums reported to be low-chill. During the project numerous grafts were made from low-chill peaches such as Tropic Snow (200 chill units), Tropic Beauty, (150 chill units), Tropic Sweet (175 chill units) and Florida Prince (150 chill units). These commercial peach trees were grafted on Nemaguard (800 chill units), Hansen and other un-named rootstocks requiring much greater chilling time (upwards of 400 to 1,000 hours). Research reports from universities in Texas and Florida stated that many plum rootstocks (genus species) would not be compatible with low-chill peaches. The no-chill project rootstock, Prunus mume, had not previously been tested. Grafting of the peaches onto the mume rootstock was 50% successful. Even with irrigation, the heat and worst drought in the area's history played a part in the low grafting success rate. Of the ten successful grafts, one tree has produced one Tropic Snow variety peach. Other grafts of Tropic Snow and Florida Prince have produced new growth and are expected to flower next year. There was no discernable difference in fruit when this was grafted onto the Prunus mume rootstock. The project also tested Methley plum and Ceylon peach, both of which have fruited in Hawaii. Grafts onto Methley plum were not successful. A variety called Ceylon Peach or sometimes Mysore Peach has fruited in low elevations in Hawaii for some time. Tests of the other low-chill peaches onto the Ceylon Peach rootstock will take place when enough rootstock can be propagated. This has also been affected by ongoing drought conditions.

The project has been successful in that we were able to successfully graft some of the new low-chill peach varieties onto a no-chill rootstock and produce fruit in Hawaii. The project collaborators are very excited to continue this research for their farms. They are working to propagate and looking to purchase more Prunus mume rootstock.

Fruits from existing trees plums were distributed to a number of chefs from the American Culinary Federation’s Kona Kohala Chefs Association. This resulted in demand for the plums that exceeds current production. At one resort the chef developed a sweet tart jelly, which is on a seasonal menu enabling two growers to sell all the crop they can produce. These growers have also started to propagate more plum trees. A 19-year tree was monitored and produced 22 lbs of fruit. This was sold to a wholesaler for $3.50 a pound ($66.50). It took 10 minutes to harvest five pound of fruit. The tree occupied just under a 10 x 10 foot space. The plums have also been sold successfully at a farmers' markets ($5.00 per pound) and at a local grocery at $3.50 per pound. wholesale. The project coordinator also developed both plum jam and oriental style plum sauce using locally grown plums. In all cases the wholesalers, grocers and market customers have asked for more, showing a clear demand for much more locally grown stone fruit.