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Premature Fruit Drop

As new parents of a fruit tree, you most likely are excitedly looking forward to the first crop your tree produces. As spring time flourishes and you see your new fruit form, you start preparing for what you will do with that first delicious bite. And then out of nowhere (it seems!) you come out one morning to find that beloved first fruit on the ground, before it was ripe. So what has caused this? There are a variety of reasons and we list the top 5 for you to utilize as you troubleshoot to find a solution.

#1 Inadequate Pollination

Naturally, insufficiently pollinated young fruit will be shed. This can be caused by an inadequate presence of pollination helpers (like bees) during the bloom time of your trees. You may encourage a greater population of bees and other beneficials by companion-planting roses and other garden plants that will attract them and avoid using pest control sprays while your tree is blooming.

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.

#2 Overbearing

Trees that try to overbear, especially in their early fruit production years, may succumb to early fruit drop. Young trees are more prone to drop fruit, whereas older, established, developed trees tend to more regularly store and make use of their reserve food. This food is stored while a tree is dormant and is used in the production of fruiting buds that swell and bloom in the spring. If a tree has not developed a system to properly store reserve food, the fruit that forms will compete for nutrients to feed them.

If there is too much fruit forming, “survival of the fittest” kicks in, and the tree drops fruit. If the competition for nutrients is between the young fruit and the tree itself, your tree will sacrifice the lot so that it can live to fruit another year.

Some trees shed the newly formed fruit to protect their branches from the stress of the added weight. If the fruit is allowed to remain on the tree, and it grows to its full size, the branches will break or bend down to the ground, which could be an invitation for pests and disease. The outcome is much more detrimental than simply having the underdeveloped fruit be shed to the ground.

If a tree is allowed to sustain a vigorous crop load, and a drop doesn’t occur, one result may be that the tree that bears biennially. The tree will have a bumper crop one year, where it produces an abundance of fruit, and then it will take the next year off to recover. Fruit bearing is a stress on the tree, so it is not unusual that, during this recovery year, your tree will not have a fruit crop.

To avoid fruit drop as a result of overbearing, we recommend thinning the young fruit before the tree drops it. In general, it is best to leave 4-6 inches between each fruit and break up any clusters that may form. You may use small, sharp pruners to remove the fruit or simply pluck it off with your fingers.

If you pinch the blossoms off your tree before the petals drop and fruit begins to form, you will also be able to help avoid overbearing and fruit drop.

#3 Water

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.

#4 Weather

Freezes, wind and hail can cause fruit drop as well as other types of damage to trees and their fruit. If you expect a frost or freezing temperatures in your area during the growing season, you can cover your tree with sheets and even wrap holiday lights around it for extra insulation and warmth. Supporting your young tree with tree stakes can help prevent damage to the tree during windstorms. The best thing you can do for your tree is keep it in good health —that way, even if the weather takes some fruit, your healthy tree will stick around to keep producing for you in years to come.

Of course you may find that these general troubleshooting reasons do not apply to your situation and tree. The best next course of action would be to contact your local Agriculture Extension agent to test the soil. It is generally a free service and is vital in helping to diagnose what might be troubling your fruit tree. 

August 20, 2018
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