Wednesday | July 26, 2017
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Bayfront’s beautiful blossoms

What are those beautiful multicolored trees along Bayfront in downtown Hilo? Earlier this fall, they displayed stunning pink, white, orange and red flowers.

They are rainbow shower trees (Cassia x nealiae), native to Southern Asia. The rainbow is actually a hybrid between the golden shower (Cassia fistula) and the pink shower (Cassia javanica).

There are different varieties, each with a different array of stunning color combinations: orange, pink, white, peach and sherbets.

The tree itself is fast growing, can reach up to 65 feet high and spreads out its branches like an umbrella.

It is fairly drought tolerant but grows best in a hot tropical or subtropical climate. Trees can be propagated by air layering or grafting.

In addition to the trees lining Kamehameha Avenue along Hilo Bay, rainbow shower trees are growing at Liliuokalani Park.

Besides these, a few other types exist in Hilo:

l The white shower tree, producing creamy white blossoms with a hint of yellow, can also be found in downtown Hilo.

l The pink shower tree producing large showy pink flower clusters can be found on the Hawaii Community College Campus.

l The golden shower tree produces brilliant yellow flowers and can be seen at the Kawamoto Swim Stadium and near Mo‘oheau County Park.

Hi, Nick. I’m a regular reader of your column and find much valuable information there. Thought you’d appreciate and share a wonderful source of native plants in East Hawaii: Big Island Plants ( They propagate an impressive range of beautiful and healthy native plants, from the common (ohia, hapuu, mamaki) to less well-known (akia, oha wai, hoi kuahiwi, ilihia). The variety of species includes plants suitable for gardens all over our island’s wide range of ecosystems from coastal areas, misty upslope forests and drier deserts. For more information, contact Kim at — Aloha, R.

Insect control with neem

The neem tree (Azadirachta indica) is a fast-growing shade tree native to Southeast Asia and India. Compounds (Azadirachtin) extracted from the seed have been found to possess pesticidal qualities; the greatest concentrations of these substances are found in the seed.

Also extracted from the seed kernel is the oil. Neem oil, like other horticultural oils, works by suffocating the insect, coating its body and blocking the breathing openings. Products are available which contain neem oil alone or with azadirachtin. In tests involving the control of aphids, products containing both had a greater efficacy than either ingredient alone. Neem oil can also prevent the germination of some fungal spores such as powdery mildew.

Azadirachin, the active ingredient in many neem products, actually consists of more than 25 closely related compounds. This ingredient works in several ways.

1. It can act as a feeding deterrent against a number of insect pests.

2. It can disrupt the molting process so that the immature larvae do not develop into adults.

3. Some insect larvae may also be killed by direct contact with the spray.

4. Adult insects are normally not killed but mating may be disrupted.

5. Azadirachtin also has a repellent effect on certain insects and mites. Insect pests affected by azadirachtin include aphids, beetles, caterpillars, lace bugs, leafhoppers, leafminers, mealybugs, psyllids, thrips and whiteflies. Generally, neem will have less of a detrimental effect on beneficial insects (parasites/predators) compared to the broad spectrum pesticides.

Multiple applications of neem are generally recommended. Frequent spraying is more effective because neem does not persist on plant surfaces. Like other botanical insecticides, it is quickly broken down by sunlight and washed away by rain.

For smaller plants, neem seems to work well as a soil drench; the product is absorbed by the roots and translocated systemically throughout the plant.

Another product sold as a fertilizer is neem cakes. They are the residual seed meal remaining after extraction of oil from seeds.


In a previous article, I wrote about the hummingbird’s role in pollination.

The information was helpful to many people throughout the U.S., however, I failed to mention that hummingbirds do not reside in the State of Hawaii. What people are actually seeing when they observe a “hummingbird” in Hawaii, is a large moth; they are two species of sphinx moth’s, Macroglossum stellatarum and Macroglossum pyrrhostictan. Sometimes called hummingbird moths, they have a long thin proboscis (mouthpart), which they insert into flowers to sip their nectar.

Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years. Email your questions to Sakovich at


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