Thinning Out Apples: Learn How And When To Thin Apple Trees
Many apple trees thin themselves naturally to some extent, so it should be no great surprise to see some aborted fruit. Often, however, the tree still holds onto a surplus of fruit which results in small, sometimes misshapen apples. Read on to find out how to thin apple fruit.
Reasons to Thin Apple Trees
Apple crops vary from year to year. In years of plenty, thinning out apples allows the remaining apples to grow larger and healthier. Apple tree thinning removes some of the small apples from the cluster, enabling the tree to expend its energy on the fewer remaining apples.
Thinning also gives you an opportunity to inspect the tree to see if there are any diseased or broken limbs or any early signs of insect infestation that can then be effectively treated.
Apple tree thinning also reduces the weight of the apple crop on the branches of the tree. This prevents potential breakage of the limbs.
Apple Thinning Guide
The selection, timing and method for thinning out apples is critical to the end result — the production of shapely, flavorful and large fruit. The following apple thinning guide will instruct you on how to thin apple fruit.
How to Thin Apples
Thinning an apple tree can take place throughout the summer but, ideally, you should thin in the late spring. The tree will naturally thin itself, called the “June drop.” This doesn’t always occur in June, however. It depends on your region and the cultivar, but it does happen a few weeks after the fruit sets. It is a good time to re-inspect the tree to see if any manual thinning needs to occur.
Prior to thinning the apples, take a good look at the tree to see how bountiful it is bearing this year. Fruit is borne in clusters of two to six small fruit. A large crop means that you did not thin enough the prior year. This means you should be a bit more aggressive when thinning this year.
To remove the fruit from the tree, you can pluck by hand or use sterilized, sharp pruning shears or scissors. To sterilize the shears, simply wipe them down with rubbing alcohol. This will prevent any pathogens that may be on the pruners from contaminating the apple tree. Be careful not to damage the spur when you are thinning, which may decrease the successive year’s crop. If you are hand plucking, grasp the small fruit between your fingers and pull backwards so the stem snaps cleanly off.
Of the two to six small fruit, thin to one large, healthy apple. First, remove those that are malformed, diseased or insect damaged. Next, remove those apples that are smaller than the rest of the cluster.
Finally, you may have to make a tough choice but it’s all for the good in the end. You may have to remove some apples that seem to be perfectly healthy, a noble sacrifice for the end goal of big, plump, juicy and crispy fruit. Out of the two to six apples in a cluster, you want to narrow it down to one big, healthy fruit with about 6-8 inches (15-20 cm.) between the other apples left on the tree. This single large, healthy fruit is called the “King’s fruit.” If you have two similar looking fruit left on the cluster and just can’t decide which one to thin, remove the one which has less sun exposure. That is, the one on the underside of the leaves. Keep the apple that has the best exposure to light and air.
Be methodical when thinning the apple. Begin with one branch at a time and systematically go from limb to limb. This may be a bit time consuming, but it isn’t difficult and the bonus at apple harvest time makes it all worthwhile.
Alternative to Manual Thinning
If all that monkeying around in an apple tree isn’t your cup of tea, there is an alternative to hand thinning. A foliar application of the insecticide Sevin will accomplish the same goal. This product is helpful if the tree is very large or you have a home orchard. The down side is that you do not get to hand pick which apples are being discarded, too many or too few apples may be removed and/or the possibility of increasing the mite population is possible.
If you decide to use Sevin, read the instructions carefully prior to handling. Mix Sevin in the amount of 2-4 tablespoons (30-60 mL.) per gallon of water and apply foliarly, enough to really wet the leaves. Apply 10-14 days post bloom. Wait another seven days and reassess. The number of remaining fruit may be sufficient or down to a few that can be hand removed or a second application of Sevin can be applied.
How to Thin Apples on a Tree
Apple crops vary each year based on early growing conditions. In bountiful years, thinning the tree enables the remaining apples to grow properly. Thinning also reduces the weight on the tree's branches to avoid broken limbs. The timing, fruit selection and method of removal all affect the success of the thinning process. Selective thinning instead of randomly removing fruit optimizes your apple tree's chances of a large harvest of well-shaped and flavorful fruit.
Assess the apple crop as it begins growing to determine the need for thinning. A large apple crop indicates that you didn't thin enough the previous year so remove more apples during the current growing season. On years with a small number of apples, thin the current crop less than the previous year.
Inspect apples as soon as they begin growing to look for poorly formed, damaged or pest-riddled fruit. Pull these apples as soon as you see them.
Watch for the "June drop," when the tree naturally thins itself. The June drop doesn't necessarily happen in June, but occurs a few weeks after the fruit sets. Monitor the trees once the fruit sets to look for dropping apples. View the branches to determine if the drop left enough room for the remaining apples to adequately grow. If the tree still has clumps of several apples together, manually thin the remaining fruit.
Work on one branch at a time to ensure the entire tree is thinned adequately. Choose a starting spot on the tree and work around so you don't miss any limbs.
Select the smallest and least healthy apples for thinning. Leave behind the blemish-free apples that are already thriving.
Cut the apples off the tree with sharp scissors or pruning shears to avoid damage, so fruit grows in that location the following year. If you remove the apples by hand, twist the fruit instead of pulling straight down, which can hurt the branches. Avoid removing or damaging the spur when thinning apples, as you may decrease next year's crop.
Remove fruit so the strongest in each cluster remains, with about 6 to 8 inches between the apples left on the tree.
Cooperative Extension: Tree Fruits
When conditions are good for bloom and pollination, trees can bear an excess number of fruit, which is a strain on the health and hardiness of the tree. In addition, limbs may not have the structural strength to support the weight of all the fruit and could break or snap off the tree near harvest time. To counteract this problem, some of the fruit should be removed in mid to late June, but fruit thinning in July will also be beneficial. Thinning fruit early in their development will benefit the tree more than removing them close to harvest time.
The amount of fruit to remove depends on the type of tree and how many fruit it currently bears. For peach, remove enough fruit so that there is no more than one fruit for every eight inches of shoot length. This is usually one or two fruit on each shoot. Plums can carry twice as many fruit as peach. Pears and apples bear fruit in clusters. It is a common practice to remove all but one fruit in each cluster.
Chemical thinning is an option for large apple orchards which are time consuming to thin by hand. Spraying carbaryl (Sevin™ insecticide) once or twice in the four weeks following bloom is an effective way to thin apple fruit, but avoid spraying when trees are in bloom or bees are present in the orchard. Two weeks after applying carbaryl, some of the fruit will be shed from the tree. For effective thinning and safety precautions, read and follow the instructions on the product package or label. Carbaryl does not thin peach or plum fruit. For more instructions on spraying, see the section entitled “Spraying Fruit Trees.”
Apple Chemical Thinning
Apple chemical bloom and postbloom thinning programs are intended to reduce the current season’s crop load in pursuit of three fundamental goals: 1) inhibit fruit set to minimize green fruitlet hand thinning 2) improve size and quality of surviving fruit and 3) promote return bloom to encourage annual cropping. Successful chemical thinning usually requires comprehensive programs employing multiple chemistries during the bloom and postbloom period. Bloom thinners (applied when flowers are open and viable) reduce fruit set by damaging flower parts and/or inducing plant stress. Most postbloom thinners (applied after petal fall) typically mimic the effect of plant hormones to elicit a specific physiological response (e.g. increased ethylene evolution, which triggers fruitlet abortion) to achieve reductions in crop load.
Fertilized flowers become more difficult to thin with each passing day, making early, aggressive thinning strategies more successful than those which rely primarily on chemical applications after 10 mm fruitlet size. Research indicates that early thinning results not only in more significant reductions in fruit set, but greater improvements fruit size, fruit quality, and return bloom. Even with more aggressive chemical rates, applications of postbloom chemical thinners after 15 mm fruitlet size are usually of marginal benefit in typical Washington conditions. Timings based on weather and crop developmental stage (i.e. mean fruitlet diameter) are generally more reliable and accurate than those based on the calendar (i.e. days after full bloom). Application timing for chemical bloom thinners may be improved with the guidance of pollen tube growth models available on WSU's AgWeatherNet system (weather.wsu.edu) these models can be used to predict when apple flowers are effectively fertilized, which can be helpful information when making chemical thinning decisions.
Chemical thinning efficacy is a function of many factors, including apple cultivar and strain, rootstock, tree condition, pollen strength and density, bee activity, weather, product chemistry, rate, application method, timing, and coverage. Therefore, thinning programs should be customized to individual blocks. Select materials, timings, and rates accordingly and observe label recommendations and restrictions. Spring frosts can induce significant fruitlet abortion in lower parts of the tree, but upper parts of the canopy may still be over-cropped in these cases, thinning sprays targeted to tree tops are often advisable to keep the trees in balance and discourage alternate bearing.
Response to chemical thinners can vary relative to weather conditions before, during, and after application, especially in the case of postbloom materials. Caution should be exercised when applying thinning materials in temperatures above 80°F, especially during dark, cloudy conditions, as fruitlet abortion and/or phytotoxicity may become excessive in some cases. Thinner efficacy may be diminished below 60°F, but low temperatures can also temporarily mask the symptoms of a significant thinning response growers dissatisfied with the performance of thinning sprays during cool conditions may be well advised to wait for a few days of warm temperatures to reassess fruit set before applying additional thinners. See individual product labels for additional guidance.
Fruit thinning for homeowners is one of the most difficult jobs to do when producing tree fruit. With all the expense and hard work that has gone into producing a healthy productive tree, the last thing homeowners want to hear is that they should knock the majority of the young fruit on the ground. However there are a couple of important reasons why fruit crops should be thinned. The most important reason to thin fruit is to increase fruit size. Another significant reason to thin fruit is to reduce over bearing that often leads to a heavy crop in one year and almost no crop in the second year. A third reason to thin fruit is to reduce limb breakage that occurs when too much fruit is left and the fruit begins to size.
Most deciduous fruit trees benefit from fruit thinning. Apples, pears, Asian pears, apricots, plums, peaches, kiwi, and persimmons all respond positively to fruit thinning. Cherries and nut trees are usually not thinned. Why do these fruits benefit from thinning? Because thinning balances the amount of fruit left on trees with the leaf surface that provides the energy to grow and ripen fruit. Leaving too much fruit on a tree creates a burden for the tree and takes energy from other processes occurring at the time of fruit development. One of those processes is fruit bud development for the coming crop. When too much fruit is left on a tree, fruit bud production for next year will be limited, causing the tree to have a light crop next year. Also, when too many fruit are left on a tree the competition between fruit for scarce nutrients will limit the size of each individual fruit.
Learning how much fruit to thin off your tree will take some practice. Each fruit type will require a little different method. When working with apples, Asian pears, and European pears, thin fruit to one per spur. The spur is the short woody structure where flowers arise. You should leave only one fruit for about every six inches of branch. If your tree is healthy and vigorous it will have more than one spur every six inches along a branch. So you will need to leave some spurs with no fruit on them. This helps to balance your crop for next year. When choosing which fruit to leave look for the largest fruit. Fruit that is small or damaged should be dropped first. Homeowners should thin fruit as early as possible. Thin before each apple reaches the size of a dime in diameter. This usually occurs within the first 20 days after petal fall. Removing these small fruit early will keep energy available for the fruit that remain and fruit buds for next year. Thinning by homeowners is typically done by hand. Be careful not to break off the spurs while thinning. Spurs will produce flowers and fruit for many years if not broken during thinning and harvesting.
When working with apricots, peaches, nectarines, and plums you will notice fruit is borne mostly on one year wood and does not come off a spur. Plums will be borne on both one year wood and small spur like structures. When thinning these trees try to space young fruit along the branches as singles with about six to eight inches between fruit. Young fruit should be thinned off trees within 30 days of the end of bloom. Be advised that peaches, nectarines, cherries and plums will have a natural drop that occurs near early June. This is referred to as June drop. This is the trees way of lightening the crop load. You may want to leave a little heavier crop than the final crop to see which fruit the tree intends to drop for you. And, with time you will learn how to adjust for the June drop. Some peach growers use sticks or lengths of plastic pipe to knock branches to speed up thinning. If you have just a few trees I would recommend staying with hand thinning. It will be more accurate at leaving the proper amount of fruit per branch. As the fruit matures and branches begin to bow from the weight you may need to take more fruit off each limb to protect your tree from limb breakage, especially when the tree is young. If you do not want to thin more fruit from the tree limbs you may need to use poles or props to hold up the limbs.
Remember when raising dwarf fruit trees to thin a little extra fruit off after bloom because the tree is not as strong structurally as a semi dwarf or standard tree. Dwarf fruit trees are precocious and tend to bloom and set heavier fruit crops at an early age. Protect their young branches from being overloaded in the first few years.
It is my feeling that a good pruning job helps to maintain a healthy tree by removing wood that contributes to over fruiting. Pruning is the first stage of fruit thinning. Without proper pruning fruit thinning is not a feasible practice.
Apple Thinning Guide - Learn How To Thin Apple Fruit From Trees - garden
Fruit Tree Care 101. the basic things you need to know to care for home fruit trees:
As an apple orchard, we often get lots of questions from people about how to care for their home fruit trees. There are some really great intensive guides out there on all kinds of things about home fruit tree care, but sometimes we find people are wanting to know…what is the bare basics I need to do every year to care for my home apple tree. Following this guide will not make you an expert orchardist, but it’s a good place to start if you don’t know much…
YEAR 1: Plant a tree. Spring.
It’s important to get this right so you will have success down the road.
These are things to consider when planting a tree.
OTHER IMPORTANT TIPS FOR PLANTING:
- Plant a variety that is LOW MAINTENANCE. This is the most important thing you can do. We recommend the scab free varieties like Crimson Crisp, Enterprise, or Gold Rush. Other options are: Liberty, Jonafree. These apples are resistant to a major apple disease…apple scab…and that will make your life a lot easier down the road. Other varieties are especially hard to care for and should be avoided by beginners are: Gala, Jonathan, Honeycrisp, Golden Delicious.
- Buying from an actual fruit tree nursery (somewhere online like Starks Brothers) CAN be better (depending on the source) then buying a tree you find at a retail store. These trees will come to you bare root. If you buy from a retail store, look for a healthy, semi-dwarf tree, and a variety that is low maintenance.
- Buy a semi-dwarf tree – different apple tree root stocks become different size trees. Smaller tree will be better and easier to care for. A bare root tree is OK.
- Plant your tree in the spring not in the peak of summer when it is very hot. It’s also important to be sure your tree is watered in the beginning, and to protect it from deer if that’s a concern in your area.
- You need more than one tree – at least two apple trees…three is better…or you will not have cross pollination and therefore no apples. Crab apples will pollinate apple trees too. Here is a chart to show when they would pollinate.
- When planting your tree, do not plant the grafting union belong the soil. See photo. If you plant the grafting union too deep, you will have a really big tree…bigger then you want.
- It is important to stake your tree and make sure the main center branch is growing straight up.
This is all you need to do in year 1 for your fruit tree. You should not expect to get any apples until year 3.
YEAR 1: Learn About Pruning
The other thing we advise you to do is to attend the fruit tree pruning class at Tuttles your first year or the spring of the second year. Attending this will give you an idea of what type of care you will need to do for your trees in the coming years.
YEAR 2: Thin your tree.
Thin your tree year 2 and every year after in early June.
When the apples are smaller then a Quarter in size, you will want to THIN the apple tree. This means pulling off most of the baby apples so that the apples that do develop are a nice size. The tree will always produce more apples then it needs. You will leave one apple per every six inches of branch. Another way to do this is every time you have a cluster of two or three or more baby apples together take all but one apple off. This will seem drastic, but too many apples on the tree is 1) hard on the tree 2) you will get pee wee apples 3) it will prevent you from having a good apple crop next year. This must be done before the apples are the size of a quarter.
You may not have any apples on your tree in year 2. You may be able to wait until year 3 to start thinning your tree if you have no apples.
YEAR 3: Begin spraying your trees.
You will start doing this year 3-20+ of your tree.
Below is a very basic “spray guide” for apple trees. This is not meant to be an extensive guide to deal with every pest…Purdue has some great resources for this…this is meant to give you a very basic overview of spraying.
SPRAY #1: At half inch green bud stage to tight cluster (that means you can’t see any pink yet but you see some green) …click here for great photos of the different stages of buds, typically this is in early April but it varies by the year. You want to use a dormant oil spray. This will protect your tree from aphids and other pesky bugs. This is an important spray…you should not skip this one.
You can find Dormant Oil Spray online, at a hardware store, or at a farm supply store. It is called Dormant Oil. The brand is not important, but you want to be sure it is something that is labeled for fruit tree use. This is an example. You will put one application of the spray. Be sure to follow and read ALL the instructions on the label.
SPRAY #2: After bloom (when most of the petals have fallen off the tree and the apples are the size of a pea) you will want to spray your trees with a home fruit tree spray. This is different then the fruit tree oil. This spray will include both an insecticide (to deal with plum cuquillio, ornamental fruit moth, coddling moth…and make sure you have worm free apples) and a fungicide (that will deal with things like apple scab, powdery mildew, summer rots, etc). Here is an example of a home fruit tree spray. This spray at petal fall is the most important one of the year. It will do the most for keeping pests under control and making sure you have an edible apple crop.
SPRAY #3: Two weeks after Spray #2, you will spray the same Home Fruit Tree Spray again (the spray not the oil). This every two week regiment will prevent bugs from getting into your apples as they grow.
SPRAY #4: repeat spray #3 two weeks after spray #4.
OPTIONAL: if you are concerned about summer rot, you can spray additional times through the summer but this is often unnecessary for most varieties (except Gala, Honeycrisp, Golden Delicious). If you have specific pests you are dealing with, consult Purdue’s Fruit Tree Spray Guide.
Thinning Apple Fruit
Apple trees typically produce more flowers and fruit than are needed to produce a full crop of marketable fruit.В Many of the excess fruitlets will drop shortly after petal fall or later, during June drop.В In a good crop year, the remaining crop load will still be too large for the individual fruit to developВ marketable size.В Also, heavy crop loads inhibit the ability of the tree to develop blossom buds for the following year, resulting in biennial bearing.В Thinning the crop will maximize fruit size and quality, and allow for adequate flower bud initiation.
Fruit size is determined by the total cell number per fruit.В In apples, cell division ceases by about 30 days after full bloom.В Therefore, final fruit size is influenced greatly within the first month after bloom.В Likewise, initiation of apple flower buds for the subsequent yearвЂ™s crop also occurs within the first month after bloom.В To optimize both fruit size and return bloom, excess fruit must be removed during this period.В Chemical thinning preferentially removes small, weak fruit.
Determining Crop Load
The following questions will help you evaluate whether your crop needs to be thinned.В Remember, itвЂ™s better to be conservative when applying thinning materials.В ItвЂ™s possible to take more fruit off but not to put fruit back on.
- How many seeds are present?В When fruitlets are 3-5 mm, cut open a few and count the seeds.В Fruitlets with fewerВ than five seeds are more likely to drop naturally and will be easier to thin than fruitlets with more than five seeds.
- What color are the seeds?В Tan or brown seed color at this time of the season indicates that the seeds are not viable, whereas viable seeds will be white to yellow.В Fruitlets with fewer viable seeds are more likely to drop naturally, and are also more sensitive to chemical thinners. In some cultivars, the color of the pedicel (stem) is also an early indicator of whether or not the fruitlets will persist beyond June drop.В Red color in the pedicel indicates that the fruitlet will likely not persist.
- Does the tree have too many apples?В If fruit clusters are within 6-8 inches of each other and if there are more than two fruitlets developing in each cluster, there are too many apples on the tree.
- What was the crop load like last year?В Trees will thin more easily in the year following a heavy crop.
- What was bee activity like in the orchard?В Were pollination conditions good or less than ideal.В Remember that bees donвЂ™t like to work inВ cloudy, rainy, windyВ weather any more than you do.
PGR Products for Thinning Apples
Currently four materials are available for fruit thinning. The best material to use will depend on the cultivar, the condition of the trees, and time of application.
- Carbaryl (Sevin) is an insecticide that has thinning action.
- Benzyladenine (Maxcel) contains a synthesized plant hormones involved in regulating cell division called cytokinin.
- Naphthalene acetic acid (NAA) is a synthetic auxin growth regulator.
- Naphthalene acetamide (NAD) is also a synthetic auxin growth regulator.