GARDEN GUY: Seedling vs. grafted citrus trees

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Hi, Nick. I read your column in the HTH. I have a question hoping you can help with.

Hi, Nick. I read your column in the HTH. I have a question hoping you can help with.

I have a lemon tree purchased about two to three years ago from a farmers market vendor. He claimed it was a grafted Meyer lemon. It was only a few inches tall when I got it. It has been growing well and is now huge in my yard here in Hawaiian Paradise Park. It is probably 10 feet or more. It has never flowered or given fruit yet.

I think I was duped and it was started from seed, not grafted. Also, I’m not even sure if it is Meyer lemon since it is so tall. When the leaves are crushed they do smell like lemon, so I’m assuming it is some sort of lemon tree.

How long will it take for this tree to bear fruit if it was grown from a seed? Thanks.

Here are a couple of facts to help you decide what you actually have:

First, grafted citrus trees (most are actually budded rather than grafted) usually will show the ‘scar’ of the original bud. That is, somewhere between 4 and 12 inches above the soil line on the trunk a slight to obvious bulging ring will be seen around the trunk. If the trunk is smooth, with no bulge, the tree is most likely a seedling and has never been budded.

Second is the size. Meyer lemons are not vigorous trees. Ten feet tall after two and a half years is rather large for a Meyer lemon.

Thirdly, a purchased nursery tree usually will bloom and set, at least, some fruit one or two years after purchase; seedlings take much longer to bloom (approximately eight or more years).

And lastly, there are many different varieties of lemon trees. Some are commonly used as rootstocks. All in all, it seems to me you have some type of seedling lemon tree.

Another point: when citrus seeds are planted, the majority of them, but not all, will produce fruit that is true to the mother plant. The roots of these trees, however, will be susceptible to serious diseases. This is another reason to plant a known citrus variety budded onto rootstock resistant to disease.

Nick, what is this “sesame-seed-looking” problem on my bamboo? Pictures attached. Is it some kind of insect? How should I treat it? Thanks for your great column. Aloha. — Dan in Hilo

The sesame-seed-looking bumps on the bamboo stems, a fairly good description, are scale insects. They generally do not cause serious damage, are usually under good biological control and should be tolerated. If, however, the infestation surges, treatment might be warranted. A horticultural oil spray would be applicable.

The key here is when to spray and to repeat the application.

The reason for repeat applications is that certain stages of growth, such as the egg and pupae stages, are not susceptible to insecticides as are the other stages of development.

Consequently, eradication of a scale population might require as many as four applications. The five to seven day interval given on pesticide labels is to give time for the nonsusceptible stage to develop on to a susceptible one.

In addition, horticultural oil is most effective when sprayed soon after the young scales, called crawlers, have emerged. They are susceptible, whereas older, usually darker colored adults are much less vulnerable to the oil. Many of the adults might actually be dead, with just eggs underneath the shell.

Be sure to apply a thorough coverage of the oil solution to the top and underside of the leaves. Do not apply oil when the temperature is more than 90 degrees. Drought-stressed plants can be injured when sprayed with oil.

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 askthegarden guy@earthlink.net. You also can visit his website at www.gardenguyhawaii.com.