- Preventing or reducing fruit on ornamental trees and shrubs
- Northern Gardening Tips: When fruit trees don’t bear fruit, what’s the problem?
- What Is Fruit Tree Sterilization: Information On How To Sterilize A Tree
- What is Fruit Tree Sterilization?
- Can You Sterilize a Tree?
- How to Sterilize a Fruit Tree
- How to Stop Olive Trees From Flowering
- Getting Rid of Sweetgum Tree Balls
- When Sweetgum Ball Trees Fall – And How to Stop It
Preventing or reducing fruit on ornamental trees and shrubs
“Nuisance fruit” is a concern for many people including homeowners, landscapers, and park and city officials. The fruits and seeds of some trees and shrubs, such as buckthorn, mulberry, persimmon, and (female) ginkgo are unsightly, smelly, and have the potential to be a hazard when they fall on sidewalks, driveways, and other areas in a landscape. Foliar sprays are available to reduce or eliminate undesirable fruit development on ornamental landscape plants, but factors such as timing, plant stresses, environmental conditions, and lack of thorough applications may make complete control impossible. Results will vary with each chemical designed to eliminate fruit. Professional arborists also have injectable products available to reduce fruiting.
FACTORS TO CONSIDER BEFORE SPRAYING
Trees and shrubs are usually selected for landscape use based on their ornamental features, such as spring flowers, fall color, and fruit. All species of trees and shrubs produce some type of flowers and fruit, but not all of them are showy. Fruit production is part of the plant’s natural development. A plant that produces a large amount of fruit may be a desirable ornamental feature or be used to feed wildlife. Despite the value of a flowering and fruiting plant, some people consider spent flowers and fruit that fall undesirable litter. There are several methods to remove fruit or prevent fruiting. Hand-removing spent flowers or small fruits will work on a small tree, but is not a practical solution for large trees or extensive plantings. Chemical or hormone-type sprays are a more practical method, but spraying your tree can be a costly and time-consuming venture. Consider the following before you decide to spray:
Amount of fruit production. The amount of fruit a plant can produce varies from year to year. Many plants will produce heavily one year and lighter the next. Insect, disease, and damage to flower blooms can reduce fruit production. Hand-removal of spent flowers is one way to eliminate unwanted fruit.
Plant removal. If maintenance is a problem, does the plant warrant keeping? Attempting to remove fruit will become a yearly expense of time and money. When all options have been considered, plant removal may be the best alternative, and replace with a plant that holds its fruit.
Size of tree. If the tree is too large to do the work yourself, you may have to hire a licensed professional to achieve adequate results.
Timing of application. Whether you hire a professional or do the work yourself, it is essential to spray at the proper time for best results. The “window of opportunity” varies with the species and cultivars (varieties) of a plant.
WHEN AND HOW TO SPRAY
Timing. The window of opportunity for chemical or hormone-type sprays is during flowering before fruit set, usually from flower buds to the full bloom stage. It is imperative that you spray at this time for chemicals to be most effective on the flower bud. Spraying before or after flowers results in wasted time and money. The label of the product you use will give you precise instructions on how to use that product.
Temperature. Hormone-type sprays are influenced by weather conditions. Temperature at time of application is important. Follow label directions regarding temperature at application time.
Use correct concentrations. A concentration too low can increase fruit set. Excess hormone applications will cause damage to the plant.
Spray stress-free plants. Plants being treated should be healthy and vigorous. Spraying plants under stress can cause additional damage to a plant. The chemical ethephon, used to stop fruiting, breaks down into a natural plant hormone, ethylene. Plants under stress from drought, high temperatures, insect and disease problems, or environmental stress, such as compacted soils, poor drainage, or improper pH will produce ethylene. Too much ethylene can be harmful to plants, causing injury symptoms such as leaf scorch, stem damage, or defoliation, further weakening the condition of the plant.
Chemicals are available to reduce or eliminate fruit set on ornamental trees and shrubs. These products contain either ethephon or Naphthaleneacetic acid (NAA). Check with local nurseries and garden centers. Follow specific label directions for application rates and safety information.
Choose plants that have seedless cultivars. A true seedless variety is the only guaranteed method to eliminate fruit. Check with local nurseries to see which seedless or male cultivars they carry.
Use pesticides safely and wisely; read and follow label directions. The pesticide information presented in this publication is current with federal and state regulations. The user is responsible for determining that the intended use is consistent with the label of the product being used. The information given here is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement made by The Morton Arboretum.
Northern Gardening Tips: When fruit trees don’t bear fruit, what’s the problem?
Do you have an apple tree that hasn’t produced fruit, or a berry bush with no berries? There are several reasons why fruit trees or shrubs may not bear fruit, but you can sift through the alternatives and hopefully find an answer to your particular problem.
Though I want to keep this column on the “high road,” I still have to say that the first problem to consider could come under the heading of “sex and the single tree.” While some trees and bushes set fruit using their own pollen, others are a bit more like people and require two to “conceive” a fruit. So the first question to ask is whether your fruit tree has ample opportunity for cross pollination. Bush fruit, including raspberries and currants, will set fruit by their own pollen. We call this being “self-fruitful.” But some tree fruit, including apples, some cherries and plums, usually need cross pollination.
That means that you need at least two cultivars of the same kind of fruit to get good fruit set. Sometimes crabapples can be a good pollen source for eating apples, provided their bloom times overlap. But it gets more complicated when certain cultivars of apples are involved.
Most apple cultivars are cross-compatible. That means they are not fussy about what cultivar of apple supplies the pollen for fruit set, and you can plant almost any cultivar with any other and be fairly confident of good fruit set, so long as their bloom times overlap. But there are exceptions. Spur strains are poor pollinators for their parental types. For example, ‘MacSpur McIntosh’ does not work well with ‘McIntosh’. And some cultivars, among them ‘Matsu’, ‘Spigold’, ‘Gravenstein’, and ‘Jonagold’, produce sterile pollen. If you want to plant them you’ll need at least three different cultivars in the planting.
How long after you plant an apple tree should you hope to have apples? There’s no easy answer to this question. One factor in a tree coming into bearing is its age. As odd as it sounds, we begin counting the age at planting, so no matter if we plant a one year old tree or a three year old tree, they are both one year old, one year after planting. Generally, we figure that an apple tree should come into bearing by its third to fifth year. Plums and some other fruit may bear in their third year.
If the tree blooms but sets no fruit, the answer lies elsewhere. All fruit trees must be pollinated to produce fruit. If there are too few bees, or if the weather is stormy or cold during bloom, the bees can’t do their job. Again, be sure that you have at least two cultivars of the same fruit planted within 40 feet of each other; say, a tree each of ‘Haralson’ and ‘McIntosh’ to cross-pollinate each other. And when selecting your trees, be sure their bloom period overlaps, or no cross-pollination can occur.
Apple trees are almost always grafted. Tasty apple cultivars are grafted onto rootstocks that give desirable characteristics, like cold hardiness, disease resistance or dwarfing. But the rootstock upon which the detached shoot or “scion” cultivar is grafted can compound the problem. For example, some trees on seedling rootstocks can take as long as 15 years to come into bearing, though most should be bearing by the seventh or eighth year. ‘Northern Spy’ is one that takes 15 years to bear, while most of our standard cultivars like ‘McIntosh’ and ‘Gravenstein’ and ‘Yellow Transparent’, on semidwarfing rootstocks, should come into bearing by their third to fifth year. If they haven’t there’s probably something wrong. Generally, the more dwarfing the rootstock, the earlier the trees might bear. Apples on full dwarf stocks, such as M9, might even bear the year after planting.
But suppose you’ve got two semidwarf trees, say ‘McIntosh’ and ‘Delicious’, that are 8 years old and still have not flowered. What could be wrong? Here are a couple of things to consider.
First, over-pruning young trees tends to keep them vegetative and greatly delays their bearing fruit. Prune your trees only enough to train them to the desired form, whether open center or modified leader, then leave them alone. Some people prune them back hard thinking the vigorous shoots that result are good for the tree. This is far from the truth. Those shoots are not productive and can actually harbor more insects than normal shoots. So don’t over-prune.
Another reason for a delay in bearing could be over-fertilization, particularly with high nitrogen fertilizers. These promote excess vegetative growth and delay bearing. Use only enough balanced fertilizer like 10-10-10 to produce about one foot of new growth on your non-bearing tree. In other words, let the tree struggle a bit, and it’ll produce better fruit.
There are other reasons for non-bearing apple trees that we won’t go into here, but this year in particular, we may also see apple trees that flowered and don’t fruit due to late freezes.
Source: Montana State University
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What Is Fruit Tree Sterilization: Information On How To Sterilize A Tree
Neurotic gardeners can develop a love-hate relationship with their messy fruit trees. Trees with smaller fruits and ornamental specimens are especially problematic as they drop copious amounts of debris and aborted fruit. The constant clutter is an eyesore on the otherwise manicured landscape, attracting rodents and birds and posing a slipping hazard as the fruits rot.
Knowing how to sterilize a fruit tree can minimize the untidiness, yet preserve the beauty of the plant. What is fruit tree sterilization? Sterilization is simply a method to keep trees from fruiting.
What is Fruit Tree Sterilization?
When you sterilize fruit trees, you interrupt their production of auxin. Auxin is a plant hormone that controls plant growth. Growth inhibitors block transportation of auxin so it doesn’t circulate through the plant and complete its purpose.
Once auxin is blocked, the tree cells do not receive the signals they need to reproduce and change their cell responses. The idea is to keep trees from fruiting and
avoid those messy piles of debris under the tree. It is also useful in orchards to allow trees a fallow period to recover from disease or control when plants bloom for weather reasons.
Can You Sterilize a Tree?
Plant inhibitors have been used for decades by farmers, orchard owners and large scale land management corporations. It is a common practice among commercial growers to keep plants a desired shape and size while also controlling fruiting. The process is also called sterilization.
Can you sterilize a fruit tree in the home landscape? It is possible, but some plants can sustain long-term damage and fail to fruit for several seasons. The hormone controls are available to gardeners but require training and exact timing to complete the procedure. It is not an exact science even to professional arborists and results may be mixed.
It is preferred to choose appropriate trees for your landscape or even remove a nuisance tree as the chemicals used can also be harmful to beneficial insects like bees.
How to Sterilize a Fruit Tree
Home application of hormone regulators can be difficult. The first consideration is timing. You must spray when the flowers have just formed but before fruits begin to take shape. There is no way to get every bloom since the exposure to light and elements influences each area of production on the tree, but you can get the majority.
Apply when there is no wind and temperatures are between 60 and 90 degrees Fahrenheit. Follow the application rate recommended by the manufacturer. Choose the correct formula for your tree variety. Some of the chemicals available go under the name Florel, Fruitone, App-L-Set and Carbaryl. Be wary of their effects to unhealthy trees and to honeybee populations.
How to Stop Olive Trees From Flowering
Olive Trees in Garden Gethsemane, Jerusalem image by JoergK from Fotolia.com
The olive is a versatile fruit tree, producing edible fruit that produces oil for cooking and eating, among various uses. But if you are unable to harvest the fruit from an olive tree, it can create quite a mess as it drops to the ground. Prevent an olive tree from producing fruit by stopping it from flowering.
Wrap olive trees in winter. Olive trees will not set buds unless they experience a winter of warm days and cool nights, called vernalization. Most olive trees planted in Texas do not receive the right temperature cycles in winter to produce fruit, but trees in California do. To prevent your tree from experiencing vernalization, wrap it in layers of landscaping tree wrap and burlap in winter. Remove the wrap in spring.
Prune olive trees in early summer after the buds set. Olive trees are unique in that they set buds in the spring. Most other fruit trees set buds in the fall. By pruning in spring, you will remove the buds before they can bloom.
Apply a fruit-eliminating spray containing ethephon. Sprays with ethephon release a plant hormone called ethylene into your olive tree, which prevents it from flowering.
Time your application of fruit eliminator before the olive tree sets buds. Additionally, ethephon works best in spring once temperatures rise above 65 degrees Fahrenheit.
Mix fruit eliminator according to the directions on the package. Pour the chemical into a pressurized spray applicator.
Prime the applicator by pumping the handle up and down until the pressure builds within the applicator.
Grasp the holding tank in one hand and the application wand in the other. Open the application wand’s nozzle and pass the spray applicator over the foliage of the olive tree in broad, even strokes.
Getting Rid of Sweetgum Tree Balls
Proud sweetgum tree owners know the plant’s glossy, green summer glow and rainbow fall leaves can’t be beaten. But captivating colors just don’t make up for those prickly brown balls that get everywhere.
Ashley, a Davey blog reader from Connecticut, recently asked, “Any thoughts about preventing an American sweetgum tree from dropping its spiky balls? I researched online about injections you can give the tree. It is a beautiful tree, and I would hate to get rid of it because of those pesky things!”
Like Ashley, you’ve probably heard about injections to stop the balls from growing. But are they effective or even safe? Keep reading to learn more ways to tackle this prickly problem.
When Sweetgum Ball Trees Fall – And How to Stop It
When do sweetgum tree balls fall? And why?
The spiky clusters are actually balls of fruit with tiny seeds inside that birds and squirrels snack on.
By mid-fall, the balls are dead and seedless. Just like leaves, they must fall, so the tree can prep for new growth. The only difference is sweetgum balls drop all fall and winter.
Are sweetgum tree balls edible?
While they’re not edible, the balls can double as spiky mulch to keep animals away from young plants. You can even get creative and use them to make holiday trinkets or decorative balls for bowls.
How to Get a Sweetgum Tree to Stop Producing Balls
Getting back to Ashley’s question, using injections on your sweetgum tree is tricky because the timing has to be just right. For the best chance of stopping the sweetgum balls, hire a certified arborist.
The tree needs the injections right before it flowers in spring. Then, the flowers drop, preventing the balls from ever forming. It’s a narrow but critical window. At Davey, our arborists pinpoint the best application time each year using Nature Clock, a patent-pending software application that predicts bloom time and peak pest emergence.
There are also a few DIY growth-regulating sprays that contain ethephon. Follow the directions precisely as too much could stunt or stress your tree. Again, the timing is super important here, and often, there’s only one week a year you can stop the balls entirely. Otherwise, your sweetgum tree will still produce balls–though they’ll be smaller.
What Fruitless Sweetgum Tree to Plant as an Alternative
If you want to say goodbye to those balls for good (without yearly treatments), replace your tree with a fruitless sweetgum tree.
The roundleaf sweetgum is well-known as the tidy alternative to fruiting sweetgum trees.
It brings all the same charm that other sweetgum trees do: the star-shaped leaves, spectacular fall color and tall stature. Best of all, the roundleaf sweetgum grows super fast.