If you want a mulberry tree in your yard but don’t want all the mess of the fruit, then the best solution is to plant a male, fruitless variety. If there is already a mulberry tree and it is causing problems with its fruit, then pruning or applying chemical treatments may be the only answer to your problem. Here we will take a closer look at how to sterilize a mulberry tree and how to get rid of one if you don’t want it.
What You'll Learn Today
Types Of Mulberry Tree And How They Produce Fruit
Before deciding to sterilize or kill a mulberry tree, it is first a good idea to understand what type of mulberry it is.
Types of Mulberry
White mulberry is the most prolific, and there are in excess of 1000 cultivars. They originated in Asia and are used in the production of silkworms as their only food source.
Black mulberry also comes from Asia but is native to the southwest. They were popular in Roman times and spread through Europe as a valued fruiting tree.
Red mulberry is the only species native to North America.
How Mulberry Trees Produce Fruit
Only the female flowers of a mulberry tree produce fruit. Male flowers will never produce fruit but are necessary as they provide the pollen that will fertilize the female flowers.
The fruits themselves vary in color from white to red, purple, and black. The darker the fruits, the more they stain, and the excessive amounts of pollen and deeply colored fruit juices are two of the main reasons why mulberry trees get bad press.
The pollen can be highly allergenic to anyone who suffers from hay fever, and the fruit juices stain walkways, clothes, and anything else they come into contact with.
Depending on the variety, the trees can be dioecious (single sex) or monoecious (both male and female). Some mulberry trees have been known to change from one sex to the other.
The reason why mulberry trees produce such an abundance of pollen is that they are wind pollinated, so more is required to help assure pollination.
If you want a mulberry tree that won’t produce fruit, then choose a fruitless cultivar that produces male flowers, such as Kokuso 27, a white mulberry (Morus alba), or Kokuso 21, a Japanese mulberry (Morus latifolia).
How To Stop A Mulberry Tree From Fruiting?
If you have a female mulberry tree or one that has both male and female flowers, then there are two things you can do to stop it from fruiting.
Firstly prune it each year in such a way that the number of fruit-bearing flowers is illuminated or at least severely reduced, or use chemical treatments that will temporarily sterilize the tree.
We had a wonderful mulberry tree in our yard, which was pollarded. This is where all the new growth is cut off each winter. Although this will shorten the life of the tree, it also works effectively at maintaining it at a small height and preventing it from producing almost all fruit.
However, as mulberry trees are one of the few fruiting trees that grow flowers and fruits on new growth rather than branches that are one or two years old like most other fruiting trees, you will also need to remove any female flowers to be sure that no berries will be produced.
Unfortunately, due to the often thick foliage of the mulberry tree, finding the flowers isn’t always easy.
Chemical Hormone Treatments
There are chemicals that can be used to try and sterilize your mulberry tree. This includes treatments such as “Florel Fruit Eliminator,” which uses Ethephone to change the hormonal balance in the tree.
The main problem with using chemical treatments is that they must be applied at a very specific time to work. The tree must be in full bloom, and the temperature must be between 60 and 95°F.
You must also ensure that soil conditions, irrigation, drainage, insect infestation, and disease control are all optimum so that the tree is not under any kind of stress.
This is because Ethephone makes the tree produce the hormone ethylene, and stress also stimulates the tree’s natural production of this hormone. If there is too much of it, it can severely damage the tree.
Problems such as stem damage, defoliation, and leaf scorch are all possible, and even professional companies can struggle to get the balance right.
If successful, the treatment won’t stop fruits from forming but will cause them to drop off before they mature.
Another hormonal treatment that should only be applied by professionals is naphthalene acetic acid. It is injected into the trunk but requires very exact timing to be effective.
There are also hormonal sprays that are applied during flowering but before any fruit has set.
Keep in mind that chemicals applied by professionals will likely be expensive and may not work. Or only work for a single season.
If you intend to do the treatment yourself, be sure to wear safety clothing such as coveralls, gloves, and goggles to prevent you from coming into contact with the chemicals.
Always follow the manufacturer’s instructions given on the packaging to the letter. Being careful to mix the right concentrations if they need dilution with water.
How To Get Rid Of Mulberry Trees?
Sometimes it isn’t enough to just stop your mulberry tree from fruiting, or it can be too much work or expense to prevent it from doing so every year. For this reason and various others, it may become necessary for you to get rid of the mulberry tree altogether.
As mulberry trees have shallow root systems, they can be removed relatively easily. The problem with this is that the entire tree needs digging without leaving anything in place, which leaves the potential for suckers to grow up from any remaining pieces of root.
The first job is to cut the tree down to ground level. If the tree is still quite young, you may be able to dig the roots out successfully. However, for older trees where the roots will be quite extensive, a better solution is to use a chemical herbicide.
Cut the tree down during its growing period and not when it is dormant in winter. Then immediately apply a strong herbicide to the stump. This could be glyphosate, for example, but keep in mind that this is a highly controversial herbicide that may be banned in your area.
In this video, you can see a chemical approach used by arborists to kill tree stumps and roots that will help you to remove the stump completely over time:
A more organic approach is to use something like rock salt. To apply this, drill 12” deep holes that are one inch wide all over the stump, then fill them completely with the salt. Top up regularly.
The salt leaches all of the water from the roots of the tree, starving them of moisture. Over time the roots will be killed.
Undiluted white vinegar is another natural product you can try. Apply it to the stump liberally and regularly on warm, dry days, covering it with plastic after application.
The best solution if you want the ornamental look and large shading leaves of a mulberry without the mess of the fruit is to plant a male-only variety. Keep in mind, however, that these will still produce large amounts of pollen, from which many people suffer from severe hay fever.
Sterilizing a mature tree is complex and not particularly reliable. Most sterilizing techniques are best carried out by trained professionals and will therefore be expensive. Often the end results may only last for a single year.
Sometimes, sadly, the only real option is to remove the tree altogether. This is not so hard with young trees, but old, well-established ones will be a lot of work to get rid of.
By just cutting the tree down, you won’t end the problem, as the root system will simply send up lots of saplings in an attempt to survive.
To overcome this, it is necessary to kill the roots completely with chemicals, salt, or vinegar.
To learn more about mulberry trees and many other fruit trees and crops, take a look at our other articles.