Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years and is a member of University of Hawaii Master Gardeners. Email your questions to Sakovich at askthegardenguy@earthlink.net.
Persimmon tree won’t bear fruit
Hi Nick, I have two rambutan and two persimmon trees that don’t bear any fruit; they have been in the garden for years. I have three other rambutan and one persimmon tree that do bear fruit though only sparsely. Are the nonbearing trees of the male type? I would really appreciate your answers … thanks.
Here are some facts about Rambutan, and you can decide which is correct for your situation.
1. For rambutan trees, the bloom will be enhanced in response to drought; perhaps four to six weeks of dry conditions before favorable bloom. If there is plenty of rain and no dry period, flowering will be poor. This is the most common cause of poor or no fruit production. In addition, the intensity and duration of flower development depends on the intensity of the drought.
2. Most commercial cultivars produce flowers that are female with a small percentage of male flowers; the cultivars that produce only female flowers require the presence of male trees. For our area, it is thought that rambutan trees require more than one tree or one variety in order to set a more abundant crop of fruit. If you have two grafted varieties, however, they should set a crop (if the proper environmental conditions, i.e. a drought period are met).
3. Research has shown that rambutan, like lychee, is dependent upon insects for pollination. The flowers are highly attractive to many insects; bees, flies and ants are the main pollinators.
Frequent pesticide sprays will diminish the population of these insects.
Concerning the persimmon trees, here are some pertinent facts. Many persimmon trees are dioecious, that is they produce either male or female flowers, requiring more than one tree in order for pollination to occur. The oriental persimmons can produce both male and female flowers on the same tree. Many varieties will set seedless fruit without pollination, although in some climates pollination is required for adequate production. Trees usually bear in about 4-5 years but may take up to seven years to begin bearing. They have a life span of approximately 60 years.
In Hawaii, these trees grow well above 500 feet and are raised commercially above 2,000 feet. Some varieties are alternate bearing — that is they bear heavily one year and sparsely, or not at all, the next. The California Rare Fruit Growers (crfg.org) has an excellent website which describes many persimmon varieties or cultivars.
There is a variety of lilikoi, orange-skinned with sweet white flesh that I used to enjoy when I lived on the Island of Kauai. I am trying to start it on hog wire fence at an elevation of 500 feet in Waiakea Uka. Any idea of the disease on the leaf? And a treatment?
— Mahalo, Dan
The pictures exhibit no specific symptoms of disease. Some of the poorer looking leaves, however, could possibly indicate a root problem. This is especially true for young plants which have been getting too much water from either irrigation or rain. If just a few of the leaves look unhealthy, there is no need to worry yet. The plant may grow out of its troubles. If the problem is a soil disease, there is not much to do except provide less irrigation. For problems dealing with excesses or deficiencies in the soil, I would recommend a soil analysis.
The following website provides an excellent description of the various diseases of passion flower: http://www.globalsciencebooks.info/JournalsSup/images/0812/PT_2%281%291-19o.pdf
In addition, you can always bring samples to Brian Bushe at the CTAHR office on Komohana Street in Hilo; there is a fee.
Class Announcement
I will be teaching a gardening class from 9:30 a.m.-12:30 p.m. on Saturday at the University of Hawaii at Hilo campus. The class is titled “Common Pests of the Garden & How to Control Them.” We will look at many of the widespread diseases and insect pests that attack garden plants. Call 974-7664 to register, or go online at http://hilo.hawaii.edu/academics/ccecs/fitness/. There is a fee.
Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years and is a member of University of Hawaii Master Gardeners. Email your questions to Sakovich at askthegardenguy@earthlink.net.