Wednesday | December 13, 2017
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How much citrus can go into compost piles?

Dear Garden Guy, we have a bumper crop of lemons and limes this year. We compost all of our kitchen waste, but my husband thinks all of the citrus peel and whole fruits will not be good for the compost pile because of the acidity. Should I limit the citrus in the compost? — Thanks! R.

Even if the entire compost pile were made of citrus, once it is decomposed, this small amount, in comparison to the vast amount of soil, would not have much of an effect on the overall acidity. In addition, most soils are well buffered. In some California citrus orchards, the pulp from the processing plant is dumped on the orchard floor with no ill effect. Go ahead and use it.

Aloha, I’m a first time zucchini grower on Oahu and have managed to start 12 seedlings of zucchini to grow. I want them all to be successful enough to fruit without things like mildew or insects stopping me. Any advice on what to look out for? I planted 12 to increase my chances. Also, they are currently in containers smaller than one gallon. Have you tried transplanting your zucchini before? Any advice there as well? — Thanks, Jeff

You’ve picked a challenging crop to begin your garden adventure!

One difficulty in transplanting seedlings is the damage that can occur to the tiny root hairs when the plants are transferred from the pot to the field.

Consequently, plants will stagnate while new root hairs are being regenerated, this is called transplant shock. Zucchini, along with other cucurbits, are sensitive to this situation but most often do recover, although rather slowly. When transplanting, be gentle, disturbing the root ball as little as possible.

Transplanting, however, may be the least of your worries. Powdery mildew can be a problem. Next time, begin by purchasing varieties of seed that are powdery mildew resistant. This does not mean the disease will go away, but will be minimized. Sprays such as baking soda (commercially purchased as Kaligreen), wettable sulfur and horticultural oils can also be used to combat the disease. In addition, there is a biological product called Serenade, which is a bacterium that helps prevent the powdery mildew fungus from infecting the plant. Repeat applications on any of these products will be needed. When plants are young and vigorous and have adequate water and nutrients, powdery mildew will be held at bay. As the vigor of the plant declines, so will its ability to resist the fungus.

Again, use resistant varieties.

And now for the most troublesome problem: the pickleworm. This moth, whose wing span is about one inch, was introduced into Oahu in 2003. Usually eggs are deposited in the bloom where larvae enter the young fruit and begin feeding.

Consequently, the tiny fruit will turn yellow and drop. Sprays are often not effective since the larvae are inside the bloom or fruit. Repeat applications of an organic insecticide called Bt (a bacterium, bacillus thuringiensis) may help.

The best control measure thus far is exclusion. Placing some type of netting (3/4 inch bird netting) over the crop will keep most moths out and still allow bees to pollinate.

Zucchini and other squash bear two types of flowers on the same plant, male and female. Gardeners are often concerned because the first blooms do not produce any fruit. This is simply because the first flowers produced on the plants are male.

In time female flowers will form followed by fruit. Female flowers can easily be distinguished from the males by the presence of a miniature fruit at the base of the flower.

As you can see, there are many challenges to growing zucchini. Yet this versatile vegetable is used in many recipes and will be worth the care when finally harvested.

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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