Q: I have a persimmon tree purchased nine years ago. In the past three years, the fruit hasn’t grown larger than a grape, changing color but not expanding in size. The tree receives sun all day long. Will I ever again see any full-size fruit from this tree? What am I doing wrong?

— Mrs. Marty Mayer, Northridge

A: Persimmon is one of the most sensible fruit trees for Valley gardens. A persimmon tree is relatively easy to maintain. Once the tree has established its main branching structure after a few years of growth, pruning is no longer necessary.

A persimmon tree’s mature size is a manageable 30 feet. The tree is also reasonably drought tolerant and should not require more than a single weekly soaking.

Soil beneath persimmon trees needs to dry out between waterings. In fact, as a general rule, you should not water any plant until its soil is dry at a two-inch depth. I also don’t think the brick circle around your tree is a good idea since it could encourage water to collect inside it.

Here’s a good rule of thumb regarding plant health: unless you see clear signs of disease or insect damage, plant problems are nearly always associated with what is happening below. Typically, the soil is too wet or, on fewer occasions, too dry. Also, if the base of a trunk is always moist — a consequence of excessive irrigation, too much shade, circling plants or ground cover that touch the tree, or mulch that covers the trunk base — you are almost sure to have problems, including root and wood rot that can cause death of the tree.

An alternative explanation for your tree’s travails is that it was planted in a root-bound condition. This means that you planted a tree that had been growing in a container too small for it, whose roots were growing in a circular pattern inside the container.

Such trees perform well for the first few years until, eventually, the tree suffers since its increased top growth is not compensated by increased root growth. It is as though your tree, due to its circling and strangled roots, is still growing in its original nursery container.

One additional persimmon issue bears mentioning: premature fruit drop. The reason persimmons fall from the tree before they ripen is the result of parthenocarpy, which a fascinating botanical phenomenon.

Parthenocarpy (a word that combines “parthenos,” meaning virgin, and “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 is a female flower part that grows in response to pollination and fertilization of the ovum or egg. 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 grows out from the male pollen grain into the female stigma and then continues to grow 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 that is located there in the ovule (egg).

This mixing of male and female genetic material is known as fertilization, from which a seed is produced.

In most plants, hormone exuded by a developing seed stimulates growth of the ovary into a fruit. But in a few select plants — such as bananas, persimmons, figs, navel oranges, 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.

The most popular persimmon variety is ‘Fuyu,’ whose fruit often drops when it develops parthenocarpically. To ensure a crop, plant a pollinator variety such as ‘Gailey’ next to your ‘Fuyu.’

Early fruit drop can be a self-regulating tactic that a fruit tree employs when it does not have enough resources to ripen all of its fruit. By the same token, an unsatisfactory watering regime, whether the tree is getting too little or too much water, may be implicated in early fruit drop. For this reason, mulching is recommended, a practice that lengthens irrigation intervals while keeping soil moisture at a constant level.

But be careful: excessive fertilization with nitrogen can also lead to early fruit drop since there will be a tendency toward explosive vegetative or foliar growth at the expense of fruit development.

Finally, lack of bee activity and, therefore, limited pollination and seed formation, will also contribute to premature fruit drop.

Source - http://www.dailynews.com/