FRUITFUL PRODUCTION IN DRY WINTER.

Byline: Joshua Siskin

With the recent precipitous rise in fuel prices and the forecast of a dry winter - which could lead to increased water prices - the cost of food could suddenly increase as well. Perhaps this explains a flurry of letters and e-mails just received by this writer, all having to do with homegrown fruit.

Mildred Bradley wrote from Sylmar about her persimmon tree. ``I have had a Japanese persimmon tree for over five years,'' she explained, ``and every year I've had fruit, but when it gets a nice size they dry up and fall off. What am I doing wrong?'' The reason your persimmons fall from the tree before they ripen is the result of parthenocarpy, which is one of the most fascinating botanical phenomena. Parthenocarpy (``parthenos'' meaning virgin; ``karpos'' meaning fruit) is the production of fruit without fertilization.

In certain persimmon varieties, parthenocarpically produced fruit is highly susceptible to dropping from the tree before it matures. In general, what we call a fruit is actually a fully developed plant ovary. The ovary - which consists of one or more carpels - is a female flower part that grows in response to pollination and fertilization. Fertilization occurs after pollination - that is, after a male pollen grain from one flower is transferred to the female stigma of another flower - occurs. A tube then grows from the pollen grain through the stigma and down through a filament called a style. At the base of the style, male genetic material from the pollen grain unites with female genetic material in the ovule or egg; this mixing of male and female genetic material is known as fertilization, from which a seed is produced.

In most plants, hormone produced by a developing seed stimulates growth of the ovary into a fruit. But in a few select plants - such as bananas, persimmons, figs and Satsuma plums - fruits may grow without the benefit of seed formation. In the case of persimmons, although fruit can develop without seeds, larger crops will result and fruit will stay on the tree until ripe when pollination/fertilization and seed development occurs. You may well have a popular astringent variety of persimmon called ``Fuyu,'' whose fruit often drops when it develops parthenocarpically. To ensure a crop, plant a pollinator variety such as ``Gailey'' next to your ``Fuyu.''

Other factors that promote persimmon fruit drop include excessive leaf growth from overfertilization, insufficient light and lack of bee activity.

Mike DeSantis, who lives in Montrose, laments his inability to grow mango trees. ``I have started several mango trees - from seeds in store- bought mangoes - that grew to about 30 inches tall and then died. My soil is sandy and I have peach, nectarine, grape, loquat, fig, plum and many other types that are all doing fine. Why can't I grow mangoes?''

Mangoes are a tropical fruit and not really meant for your moderately cold winter climate. However, you might succeed in growing them in a protected location - next to a south-facing wall, perhaps. Still, your sandy soil presents a problem. Mangoes crave an evenly moist soil, which means you will have to water them more often than the rest of the trees and vines that you mention.

Jacob Shaya from West Hills complains that ``the fruit that I got from my 'Black Mission' fig tree was not as sweet as every other year. My tree is quite mature, about 8 years old, and looks healthy.'' Perhaps your tree is getting more shade now than previously due to adjacent trees that may have grown up around your fig over the past eight years. Trees growing in reduced light are often quite healthy and show off lush leaves. However, less light also means less sugar formation which, in the case of fruit trees, means you harvest a bland crop.

You might also heed the advice of Betty Jane Kadlecik-Yates of Sherman Oaks, who has large and abundant fruit on her two fig trees, which are about 50 years old. ``We prune our trees severely,'' she wrote, ``leaving only two buds per shoot. We cut back any limbs that have grown too far out or are crossing. We also prune out any suckers or small, nonproducing branches as the year progresses.''

J. Thurman, in an e-mail from the Antelope Valley, wants to treat his peach tree for pests and has been told to make a ``sticker application,'' which he does not understand. In such an application, you mix a surfactant, which has a detergentlike effect, with your pesticide of choice. A surfactant makes water and solutions stickier so that the chemical you apply will stick to the peach foliage and not bead up or drip off. Any well-stocked nursery should carry surfactant, also called a ``sticker'' or ``wetter sticker.'' Surfactant can easily burn foliage, so make sure you use it sparingly, in accordance with instructions.

TIP OF THE WEEK: J. Thurman also asks about growing quinces. The quince (Cydonia) is botanically similar to the apple and the pear. That being said, it is less fussy about growing conditions than either of its more popular cousins. It is self-fruitful, which means that a single tree will produce a crop. It does not require much fertilization and suckers heavily. Remove suckers - they rob valuable energy from the tree. Remember that quinces, like pears, ripen off the tree. While on the subject, you should consider planting flowering quinces (Chaenomeles), which are brilliantly blooming small trees that flower in red, salmon and coral colors in fall and winter.

GARDENER: Sue Bye-Walsh

Residence: Canyon Country

Plant of interest: Aptenia (``red apple'')

What makes this plant amazing: Anyone who has lived in Southern California has seen aptenia - those clusters of smooth succulent leaves capped with small reddish flowers. The plant is used as drought-resistant ground cover in lawns and is also found near trails and on hillsides.

But Bye-Walsh was the first to see something no one in Southern California has ever seen: a ``red apple'' with yellow flowers. (The petals are actually white, with prominent yellow staminodes.)

She noticed the plant in her yard - one of the stems had mutated and was capped with the yellow flowers. She took it down to the Huntington Botanical Gardens, where the people there confirmed she had a one-of-a- kind plant. Since she was the first to discover it, she got to name it.

``I decided on Sunny Sue, because my name is Sue and the flower looks like a little yellow sun,'' she says. ``I thought of patenting it, but it's too easy to grow. I've sent it to other parts of the country and have quite a bit of it growing around here.''

What Joshua Siskin says: ``She could make a fortune. If you're really careful about keeping it contained, you can patent it. It all depends on whether it's pretty to look at. If it's just a botanical mutation, it's not something people would want. But if it's attractive, people are going to buy it.

``Someone created a yellow-flower African violet, and they made a fortune. The same as you would for coming up with an unusual flower color, like the black tulip.

``Succulent plants are famous for mutating, and aptenia is a succulent. It's also a hybrid, which makes it more unstable, more susceptible to mutation.''

- Mike Chmielecki

CAPTION(S):

photo, box

Photo:

Aptenia ``Sunny Sue'' is named for Canyon Country resident Sue Bye-Walsh, who discovered the mutated succulent in her yard.

Huntington Botanical Gardens

Box: Garden Wonder (see text)