Fertilizers for fruit trees

How To Fertilize Apple Trees – Tips On Apple Tree Feeding

Apple trees that are cultivated for fruit production use a lot of energy. Annual pruning and fertilizing of apple trees is integral to helping the tree focus that energy on producing a bountiful crop. While apple trees are moderate users of most nutrients, they do use a lot of potassium and calcium. Thus, these should be applied each year when apple tree feeding, but what about other nutrients? Read on to find out how to fertilize apple trees.

Should You Fertilize an Apple Tree?

As mentioned, it is likely that an apple tree will need both calcium and potassium feedings annually, but to really ascertain what other nutrients your tree will need, you should do a soil test. A soil test is the only way to really determine what type of fertilizer for apples might be needed. Generally, all fruit trees thrive in a soil pH of between 6.0-6.5.

If you are just planting an apple sapling, go ahead and add a pinch of bone meal or a starter fertilizer mixed with water. After three weeks, fertilize the apple tree by spreading ½ pound of 10-10-10 in a circle 18-24 inches from the trunk.

How to Fertilize Apple Trees

Before fertilizing apple trees, know your boundaries. Mature trees have large root systems that can extend outwards 1 ½ times the diameter of the canopy and can be 4 feet deep. These deep roots absorb water and store excess nutrients for the successive year, but there are also smaller feeder roots that reside in the top foot of soil that absorb most nutrients.

Fertilizer for apples needs to be broadcast evenly on the surface, beginning a foot away from the trunk and extending well beyond the drip line. The best time to fertilize an apple tree is in the fall once the leaves have dropped.

If you are fertilizing apple trees with a 10-10-10, spread at the rate of one pound per inch of trunk diameter measured one foot from the ground up. The maximum amount of 10-10-10 used is 2 ½ pounds per year.

Alternatively, you may spread a 6-inch band of calcium nitrate with the drip line at a rate of 2/3 pound per 1 inch of trunk diameter along with ½ pound per 1-inch trunk diameter of sulfate of potash-magnesia. Don’t exceed 1 ¾ pound of calcium nitrate or 1 ¼ pound of sulfate of potash-magnesia (sul-po-mag).

Young apple trees, from 1-3 years of age, should grow about a foot or more per year. If they aren’t, increase the fertilizer (10-10-10) in the second and third year by 50%. Trees that are 4 years or older may or may not need nitrogen depending upon their growth, so if they grow less than 6 inches, follow the above rate, but if they grow more than a foot, apply the sul-po-mag and boron if needed. No 10-10-10 or calcium nitrate!

  • Boron deficiency is common amongst apple trees. If you notice brown, corky spots on the inside of the apples or bud death at shoot ends, you may have a boron deficiency. An easy fix is the application of borax every 3-4 years in the amount of ½ pound per full sized tree.
  • Calcium deficiencies result in soft apples that rapidly spoil. Apply lime as a preventative in the amount of 2-5 pounds per 100 square feet. Monitor the soil pH to see if this is necessary, and after application, make sure it doesn’t go over 6.5-7.0.
  • Potassium improves fruit size and color and protects from frost damage in the spring. For a normal application, apply 1/5 pound potassium per 100 square feet per year. Deficiencies in potassium result in leaf curl and browning of older leaves along with paler than normal fruit. If you see sign of deficiency, apply between 3/10 and 2/5 of a pound of potassium per 100 square feet.

Take a soil sample each year to amend your apple tree feeding regimen. Your local extension office can help you interpret the data and recommend additives or subtractions from your fertilizing program.



Apple trees will survive with no feeding, especially those on more vigorous rootstocks but they will do better when fed twice a year. Feeding them will result in a far better crop of apples and also reduce their susceptibility to pest damage and diseases.

We recommend feeding with Blood Fish and Bone in early to mid Spring and then again in late autumn with the same. A major benefit of an organic fertiliser such as blood, fish and bone is that it is very unlikely to apply too much. Apple tree roots tend to absorb water and feed much better from soil which is at the edges of the tree canopy (foliage), and this gets further from the trunk as a tree ages.

For young trees sprinkle four or five handfuls of blood, fish and bone around the tree, but not touching the trunk, at both feed times. Increase the amount of feed as the tree becomes bigger. If it is applied to bare soil then work it lightly into the surface with a trowel and apply water. If it is applied on grass then rake it in lightly and then water.


Organic mulch applied around an apple tree will tend to be absorbed into the soil over the period of a year. Worms will do this by dragging the material down into the soil, water and general de-composition will also have the same effect. So it’s best to top up the mulch in mid Spring to it’s original level.

The purpose of a mulch is twofold, to reduce water loss and to suppress weeds which, if left unchecked, will use up moisture and nutrients for their own growth. For young trees (one to three year olds) the mulch should be applied to a depth of 8cm / 3in and a spread of 1 metre / yard. As the tree ages the water absorbing roots will spread out so the area covered by the mulch should increase as well. Water absorbing roots will spread at least as far as the the canopy (foliage) of the tree.


This section is about how to prevent diseases in apple trees, if you are more interested in identifying and treating existing pests and diseases then for information. The preventative measures below are for general apple tree care and do not deal with special conditions which some apple tree growers may encounter.

Some areas of the UK and some soil types are more likely to suffer from certain pests and diseases compared to others so it’s well worth while asking other local gardeners or at the local allotment what to look out for. An example would be canker which is more common on clay soils. If that’s the case then Winston, Katy, Lord Derby, Newton Wonder and several others have a good degree of resistance to canker. On the other hand, Cox’s Orange Pippin, James Grieve and Spartan are very liable to suffer from canker and are therefore best avoided.

Apple Scab is another common disease which is transferred by air and rain. So if you are on an allotment with lots of other apple trees and pear trees nearby look for resistant varieties (there are many) and avoid those prone to this disease.

Several fungal infections affect apple trees and they are notoriously difficult to cure once they take hold. The key is to prevent them in the first place by ensuring fallen leaves and apples are picked up and burnt / disposed of well away form your tree. Correct pruning, especially cutting out crossing branches and keeping the centre of the tree open will greatly help avoid diseases of this type.

If your gardening routines often result in neglect of your apple tree(s) then bitter pit may be a problem. It is caused by irregular watering and lack of some nutrients. The way to avoid it is to water and feed regularly but at the same time some varieties are very susceptible to this disease. They include Bramley’s Seedling, Cox’s Orange Pippin, Egremont Russet, Newton Wonder and Warner’s King amongst others. However, Jonagold and Gala both have good resistance.

In some areas wingless moths climb up the trunk of apple trees, normally from November occasionally right through to April and then lay eggs on the leaves. These can be prevented by grease bands placed around the trunk of an apple tree in October.


This is often a hard task to carry out, not because it takes much time or is difficult, but mainly because many gardeners cannot bear the thought of cutting off developing fruit. The truth is though that if your apple tree, particularly cooking varieties, has a large crop of developing fruit your best option is to thin the fruits out.

Experience plays a great part in knowing how much to thin out apples because different varieties produce fruit in slightly different manners. Our preferred method is to do nothing until after an apple tree has gone through “June drop” which is when many apple trees naturally shed some fruit. If the tree still looks like it will produce a lot of fruit we thin each cluster of fruit by first removing the central (“king”) apple then thinning the cluster to two healthy looking apples, one on either side of the cluster. Many apple trees will not require any manual thinning of fruit at all.


Harvesting and storing apples can be as easy or as complicated as you want. However, get it right and with three trees you can be eating and cooking apples from late August to mid-March. for our page dedicated to harvesting and storing apples.


Stick to the basics and pruning an apple tree need not take lots of knowledge and time. Read our detailed instructions and help guide on how to prune apple trees by clicking here.

Fertilizer Focus: Is Chicken Manure Good For Fruit Trees

Is Chicken Manure Good for Fruit Trees?

Growing delicious fruit is hard work and each spring, after emerging from dormancy, your hungry fruit trees will need a nutrient-rich boost to help fuel leaf growth, and blossom and fruit formation. But when it comes to fertilizer, is chicken manure the right choice?

In this blog we’ll explore the pros and cons of chicken poop and when it might be beneficial to use when mulching your fruit trees.

Hen and chicken manure isn’t always good for plants.

When Chicken Manure is Bad For Plants

“When it comes to fertilizing fruit trees, using raw and un-composted chicken manure is not a good idea.”

Chicken manure has been used to feed plants for centuries but part of what makes this fertilizer so powerful is also what makes it potentially damaging to plants. Fresh chicken manure is a wet, stinky combination of both poop and liquid that’s high in ammonia.

It’s the ammonia that can break down into nitrogen – and makes chicken manure so smelly. All plants need nitrogen as a growth booster. Too much nitrogen in fruit trees spurs the vigorous growth of branches at the expense of flowers. And with no flowers, there’s no delicious fruit.

So when it comes to fertilizing fruit trees, using raw and un-composted chicken manure is not a good idea.

When Chicken Manure is Good for Plants

The next option is perhaps using composted chicken manure which you can purchase from your local garden centre in bags, or get from a local farm.

If you’re composting your own chicken manure, you want to be sure that the fresh poop is composted with a generous amount of carbon-rich straw or other bedding. As with any composting you need a combination of carbon and nitrogen to create the perfect environment for soil microbes to get to work.

As the chicken manure sits for a while, the microbes in the soil break it down into nutrients our fruit trees can absorb and use. While this magical composting process happens, some of the excess nitrogen evaporates as ammonia gas. The compost needs to be turned several times and experts suggest the mixture age for at least six months before applying to fruit trees and plants.

After composting, the chicken manure will have small amounts of the three key nutrients all plants need including nitrogen (N), phosphorus (P) and potassium (K).

Chicken manure packs a bigger punch than composted manure from other animals. Here’s why: sheep, cow and other composted manure are about 1% N, 1% P and 1% K by weight. Chicken manure, on the other hand, can reach 5% N, 3% P and 2% K by weight.

As another bonus, manure from egg laying hens contains more calcium by weight thanks to the eggshell production process. Calcium strengthens the cells in fruit, shoots and roots for healthier and more tasty and juicy fruit.

So for a natural product, it seems you have a lot to gain and little to lose when spreading a small amount of composted chicken manure over the roots of your fruit trees.

Chicken and Hen Manure isn’t always good for plants.Chicken manure is higher in calcium than sheep and cow manure due to the calcium content of egg shells.

Dried Chicken Manure

Acti-sol produces dried chicken manure that is lower in ammonia and easier to transport.

Composted properly and used in moderation, chicken manure can be great for your fruit trees. But there is another option that’s been developed by an innovative Quebec-based company called Acti-Sol.

Acti-Sol produces dried hen manure fertilizers. Their fertilizers don’t smell because the manure is dried before it can form ammonia. Orchard People is proud to have this company as a sponsor for our information packed fruit tree care podcast “The Urban Forestry Radio Show”.

The Quebec-based company uses a unique dryer system – right at the henhouse—to quickly dehydrate fresh hen droppings. This stops smelly ammonia from forming, and leaves behind a high quality, natural fertilizer that won’t harm your plants.

Acti-Sol’s products are approved for organic agriculture. They only use manure from egg-laying hens that are not treated with hormones or antibiotics. As a result, farmers, as well as health conscious home gardeners, can sprinkle Acti-Sol hen manure on their organic crops.

So How Much Chicken Manure Should You Use on Your Trees

If you are using composted chicken manure, start with spreading just one inch of the fertilizer around the roots of your tree in the early spring and see how it affects your trees growth and production.

If you are using Acti-Sol, you may want to choose the formulation specifically for fruit trees that`s 4% nitrogen, 6% phosphorus and 8% potassium by weight (look for 4-6-8 and photos of fruit trees on the package). Acti-Sol added bone meal and natural potash to its multipurpose hen manure to meet the needs of hard working fruit trees. The extra boost of phosphorus and potassium helps with flower bud and fruit formation

Learn more about feeding your fruit trees

If you want to learn more about feeding your fruit trees and amending your soil, sign up for OrchardPeople.com’s Certificate In Beginner Fruit Tree Care at www.orchardpeople.com/workshops. It’s an award-winning home-study course that you can take anytime, using your computer or mobile device. In the 8-hour course you’ll learn how to prune your fruit trees, feed them and protect them from pests and disease. And for more free content, subscribe to OrchardPeople.com’s monthly newsletter or listen to our fruit tree care podcast at www.orchardpeople.com.

Andrea Bannister is a freelance communicator and lifelong gardener based in Toronto, Canada

You may also be interested in:

  • BLOG: Why Autumn Leaves Are The Best Fruit Tree Mulch
  • eBook: Preparing Your Fruit Trees for Winter
  • PODCAST: Do you have mites in your fruit trees?

How & When to Fertilize Young & Established Fruit Trees

Your first time trying to fertilize young and established fruit trees might not be successful if you don’t know the right fertilizer to use for those trees. Fruit trees need various macro nutrients to continue growing and we have found a couple great fertilizers that contain all of these needed nutrients. There are also some tips and tricks you should be following to ensure your fruit tree growth continues for years to come.

Best Fertilizer for Fruit Trees

There are many products available today that are great for fertilizing your fruit trees, and most of them are organic. What we love about these organic products is that they are natural and contain zero synthetic chemicals. We have found a couple products are much higher quality and work extremely well at helping grow your fruit trees quickly.

Jobe’s Organics Fruit & Citrus Fertilizer

Jobe’s Organics Fruit & Citrus Fertilizer is certified by the USDA as being organic. You will not find any synthetic chemicals in this product and it works great for both citrus trees and fruit trees. Whether you have an established fruit tree or a new one, Jobe’s Organics Fruit & Citrus Fertilizer is going to help your trees grow quickly.

This is a granular fertilizer which contains archaea, which is a proprietary microorganism that will help break down various materials. Healthy soil needs fungi, bacteria, and Archaea. This is the only product on the market that has been able to replicate Archaea and market it commercially. Using this particular product will help your fruit tree grow and it will stop unfavorable conditions from harming your fruit tree.

Dr. Earth Natural Wonder Fruit Tree Fertilizer

Dr. Earth Natural Wonder Fruit Tree Fertilizer is a very effective product for your fruit trees. This product is certified organic and it’s also Non-GMO Project Verified. The fertilizer feeds up to 2 months and it is made completely from sustainable ingredients. Just one four-pound bag can feed up up 60 square feet, which means you don’t need much in order to fertilize your trees.

You can use this product anytime of the year because it’s completely natural and safe. This fertilizer works on all kinds of fruit trees, including fruiting vines and berries. There are probiotics in this fertilizer so it’s a living soil that will reinvigorate the soil you have. The probiotics are important to help revitalize and renew the soil in that particular area.

How to Fertilize Fruit Trees – Tips & Tricks

Fruit trees can be a challenge to a lot of homeowners in terms of fertilization and growing them successfully in various climates. A lot of people also have a hard time knowing which diseases are likely to impact which types of fruit trees. There are some simple tips and tricks you can follow to make this fruit tree fertilization process much easier.

Use a Tape Measure to Determine Fertilizer Volume

You want to use the tape measure in early spring or in the winter while the fruit tree is still dormant. Look at the growth rings from the past year, and you will see that the new growth rings are a different color. Measure the new growth ring all of the way to the end of that branch.

Go around the tree and repeat this measuring process in different spots. Calculate the average of the measurements you collected in order to find the annual tree growth. You want to measure the growth rings on each fruit tree, even if the trees are the same type and age.

Mature peach and nectarine trees should have a growth between 12-inches and 18-inches, along with apple and pear trees. The spur apple tree should have grown between 6-inches and 10-inches. Tart cherry trees should have a growth of 8-inches. Sweet cherry and plum trees should have a growth of 8-inches. If your fruit tree is not within that annual growth category, then you should fertilize that fruit tree.

Conduct a Soil Test to Determine What Mineral is Needed

In order to conduct the soil test, you will need a few basic items to get started. A stainless steel digging tool, plastic bag, and a permanent marker are needed. You want to collect the sample near the roots of your fruit tree to see what minerals are needed.

You will need to contact your local extension office in order to know where you need to send your soil to get tested. Some areas prefer to come out and take a sample of the soil themselves to ensure that it’s not contaminated. There is a fee for this service and you must fill out certain paperwork to begin the process. Your results could come back within a couple weeks and it will show you the minerals found and lacking in your soil. You will also see tips for successfully growing in that particular soil.

When to Fertilize Fruit Trees

For the average person, knowing when to fertilize a fruit tree is a complicated situation. There is a right and wrong time of the year to fertilize your fruit tree. Too much or too little fertilization on your fruit tree can wreak havoc on your fruit tree as well. Follow these steps to ensure you are going about fertilization the right way.

Do You Fertilize Fruit Trees in the Fall?

You should not be fertilizing your fruit trees in the fall, because the upcoming frost could ruin any new growth that the fruit tree produced.

How Many Times a Year Do You Fertilize Fruit Trees?

You only need to fertilize your fruit trees once a year at the most. Some fruit trees might not need any fertilization for the upcoming year, which is why you need to measure to see the fertilization volume. The preferred time to fertilize the fruit tree is right before the annual growth begins, which means right before the buds begin to break. If you miss this spring window, you can fertilize up until June and it will be okay.

Sam Choan is the Founder of Organic Lesson. He started this site to share tips on using natural remedies at home when such options are available.

Colorado State University

Print this fact sheet

by C.E. Swift * (12/14)

Quick Facts…

  • A lack of adequate nutrients affects tree growth and fruit production.
  • Fruit trees can be fertilized with nitrogen fertilizer based on their annual growth rate or a soil analysis.
  • Most fruit trees require a yearly foliar spray of zinc.
  • A soil analysis can determine other nutrients needed by fruit trees.
  • Applying nutrients that are not needed can cause a nutrient imbalance.


Fruit trees are fertilized to ensure continued growth and fruit production. In the backyard orchard, proper pruning in addition to the application of nitrogen in the spring prior to or at bud break helps maintain this productive status. Other than nitrogen and zinc, iron and manganese may limit growth due to our alkaline soil conditions. Apply nutrients based on a soil test analysis conducted by the soil testing lab at Colorado State University or another analytical lab of your choice.

The amount of nitrogen to apply can be based on how much shoot growth occurred the previous season or on a soil analysis. Reduced fruiting wood and reduced fruit production results when the growth rate is less than what is recommended in Table 1.

Table 1: Annual Growth Rate.

Nonbearing Trees Last Year’s Annual Growth Rate
Apple 12 to 36 inches
Peach & Nectarine
Tart Cherry
Plum & Sweet Cherry
Bearing Trees
Apple Non-Spur 6 to 18 inches
Apple Spur-type 6 to 10 inches
Pear 12 to 16 inches
Peach & Nectarine 12 to 18 inches
Tart Cherry ~ 8 inches
Plum & Sweet Cherry ~ 8 inches

Identifying Annual Growth

Each year of growth can be identified by the ring of bud scale scars remaining when the bud at the tip of the shoot grows. A difference in color and/or bark texture is typically evident above and below the annual growth ring. Check last year’s annual growth rate at several points around the tree to determine the average length of last year’s growth. Use the average length of annual growth to determine if and how much nitrogen should be applied.

Applying Nitrogen Based on Annual Growth Rate

Stone fruit trees (i.e. peach, cherry, plum and nectarines) can be fertilized at a maximum rate of 1/8 pound of nitrogen per inch of trunk diameter (measured 1 foot above ground level). Apply this amount if the tree’s annual growth is on the low end of the recommendation given in Table 1. Apply less fertilizer if the previous season’s growth rate falls in between the recommended growth increments. If too much nitrogen is applied it can lead to excessive leaf and tree growth over fruit production.

The maximum rate of nitrogen to apply to pome fruit trees (apples and pears) is 1/10th pound of nitrogen per inch of trunk diameter (measured 1 foot above ground level). Apply this amount if growth the previous year was at the low end of the recommended rate. As with stone fruits, apply less nitrogen the closer the actual growth rate approximates the recommended growth rate.

Maintain a record on the amount of nitrogen applied each year and the resulting growth. Such records provide a guide for the amount of nitrogen fertilizer to apply to achieve the desired results.

Applying Nitrogen Based on a Soil Analysis

If a soil analysis has been conducted, the recommendations in Table 2 indicate the amount of nitrogen to apply.

Table 2: Nitrogen requirements based on a soil test.

Note: The above information is specific to apples and pears. Add 0.2 pounds per 1,000 square foot area for peaches, nectarines, apricots and plums and 0.4 pound per 1,000 square foot area for cherries.

Calculating the Amount of Fertilizer Applications

Figure 1: Annual Growth Ring –Apple

Figure 2: Annual Growth Ring –

Figure 3: Annual Growth Rings
– Apricot

Figure 4: Annual Growth Ring
– Sweet cherry

Figure 5: Annual Growth Ring
– Peach.

Figure 6: Annual Growth Ring– Italian Plum

Figure 7: Annual Growth Ring
– Santa Rosa Plum.

Figure 8: Bitter-pit and cork
spot on Honeycrisp apple.

Fertilizer products contain specific quantities of nutrient based on percentage by weight. This is indicated on the product label such as 15-1-1. The first number (15) is the percentage by weight of nitrogen, the second number is the percentage by weight of phosphorus (P2O5) and the third is the percentage by weight of potassium (K2O). For example, ammonium sulfate (21-0-0) contains 21 percent nitrogen while blood meal contains 12 percent to 13 percent nitrogen. The amount of the fertilizer product needed is calculated by dividing the pounds of nutrient needed by the percent of that nutrient in the product.

For example, if you need 1/2 pound of nitrogen for a given area and are using a product with 15 percent Nitrogen, divide .5 (one-half pound) by .15 (the percent of N in the product). This tells you 3.33 pounds of this product are needed to apply 1/2 pound of nitrogen.

Pruning and Excessive Irrigation

Pruning the same amount each year will result in the same amount of stimulated growth. If the tree is pruned more severely, apply less nitrogen fertilizer. This will help avoid excessive growth.

Irrigating too frequently or too much at one time, as is common with fruit trees planted in turf areas, stimulates growth and subjects fruit trees to possible root rot diseases. Take into account excessive irrigation and correct if possible. Eliminating the grass around the base of a fruit tree and applying a thin layer of mulch is recommended. Kill the grass with a glyphosate product, horticultural vinegar or fatty acid product such as Scythe before applying mulch.

It is highly recommended to plant the backyard fruit orchard away from turf where the trees can be watered and fertilized based on their needs and not that of turfgrass


Bitter-pit and cork spot in apples (Figure 8) is a direct result of the inability of the tree to move adequate calcium into the fruit. Small brown lesions up to ½ inch (10 mm) in diameter appear on the fruit. The area below the skin becomes dark and corky. These spots may appear at harvest or during cold storage. Young vigorous trees with few fruit and trees that are over irrigated and over fertilized are more susceptible to this disorder. Calcium sprays are formulated by adding calcium chloride to water at the rate of 3 to 4 pounds per 100 gallons or 0.63 ounces per gallon of water (see Fact Sheet no. 7.615, The Preparation of Small Spray Quantities of Pesticides.) Apply the first spray about mid-June, a second in mid-July, and a third in mid-August. Trees not affected by this condition will not need this treatment.


Iron deficiency symptoms result in the leaves at the end of the branch being yellow or light green with a network of deep green veins. Margin leaf burn may be evident. This deficiency often results in reduced fruit yields and poorly colored fruit with a flat taste. Apply chelated iron at the rates recommended in Table 4. To help correct this problem, avoid over irrigation and improve the organic content of the soil.


Zinc deficiency symptoms are common in Colorado. Since soil applications of zinc have not proven effective, the application of a zinc spray prior to bud break in the spring is recommended. However, applications made within three days (five days for apples) before or after an application of horticultural or dormant oil can cause injury and should be avoided. In this case, except for apricots, apply the zinc in the fall, after October 10. Mix 1 tablespoon of zinc sulfate in a gallon of water. Thoroughly cover the tree with the spray and apply the spray until the bark is no longer able to hold the spray and spray runs off the tree.

Other Nutrients

Other than the application of nitrogen and zinc as described above, base the application of the other nutrients on the results of a soil analysis. Foliar sprays of micronutrients can give remediation for the season if started in April-May and continued until June-July. Miracle-Gro, or a similar water soluble fertilizer can be used for this treatment. Read and follow the label directions on the fertilizer container.

Placement of Fertilizer

Nitrogen (N) and other nutrients, with the exception of zinc, can be broadcast over the ground and watered in, or applied in a band in the irrigation furrows prior to irrigation. Do not apply fertilizer against the trunk as tissue damage may result. Spread the fertilizer evenly and do not dump it in a pile at the base of the tree or injury will result. If the area to be fertilized is more or less than 1,0002 feet, calculate the amount of fertilizer to apply accordingly. Foliar applications can also be used if appropriate materials are chosen.

Table 3. Phosphorus needs based on the extraction method used.

Note: The Phosphorus extraction method used may be noted on the soil test results. If not, contact the lab to determine what method was used.

Table 4: Soil test results and recommendations.

Note: Sequestrene 138 Fe is 6 percent iron. Other chelated iron products may not be effective in high pH soil

Childers, N.F. 1978. Modern Fruit Science. Rutgers University.

Follett, R.H. and D.G. Westfall. 2004. Zinc and Iron Deficiencies, Colorado State University Extension Fact Sheet 0.545

Stacey, J.K. 1972. Orchard Management Workshop Proceedings, Cedaredge High School

Westwood, M.N. 1978. Temperate-zone Pomology. W.H. Freeman and Company.

Additional fact sheets on fruit trees and their care include:

Colorado State University, U.S. Department of Agriculture, and Colorado counties cooperating. CSU Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned.

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Fertilization Programs for Apple Orchards

Guide H-319

Esteban A. Herrera, Extension Horticulturist

College of Agriculture, Consumer and Environmental Sciences New Mexico State University. (Print Friendly PDF)

This publication is scheduled to be updated and reissued 5/06.

Many factors, including climate, soil, irrigation, varieties, pruning, insects, and tree nutrition influence the growth and production of fruit trees. Some of these factors can be controlled by growers; others cannot. Tree nutrition is probably the most important factor for a successful orchard operation, and it can be controlled through a proper fertilization program.

Sixteen mineral elements are essential for plant growth. Three (oxygen, hydrogen, and carbon) are obtained by the tree from water and air. The thirteen remaining elements are divided into two groups:

1. Major essential elements: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S).

2. Minor (trace) elements: iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), boron (B), molybdenum (Mo), and chloride (Cl).

Major elements are needed in much larger quantities than minor ones; all are found in the soil. However, it is not enough for these elements to be present in the soil-they must also be in a form available to trees so that trees can take them up and use them. Among other factors, soil pH (acidity or alkalinity) and balance between elements will affect the availability of nutrient elements in the soil.

Nitrogen, potassium, phosphorus, iron, and zinc appear to be the nutrients mainly needed in New Mexico apple orchards.

Nitrogen (N)

Nitrogen is the nutrient most used in fruit trees and is usually the first element to be considered in an orchard fertilization program, as shoot growth depends highly on nitrogen content. Nitrogen fertilizer rates for young trees are based on tree age and growth rate of shoots; fertilization of mature, heavy-bearing trees may be based in part on terminal growth. Nitrogen deficiencies can reduce fruiting and make fruit small and highly colored; leaves will be small and pale green, dropping early. Low or older leaves turn light green first; individual limbs may die and entire trees are stunted.

Excess nitrogen delays fruit maturity and negatively affects red color on apples. It also delays flowering and can promote late-season vegetative growth, increasing chances of freeze injury, especially in young trees. Excessive tree vigor resulting from too much N can be partially compensated for by late summer pruning. This has two main effects: it improves fruit color by improving light distribution and tends to limit root growth.

Recommendations for time of nitrogen application to apple orchards are often confusing and vary considerably among apple-growing regions in the country. However, a nitrogen fertilization program can be better understood if it is based on the root uptake period, nitrogen storage pattern in trees, and on time of the season or tree physiological stage.

The entire tree root system is capable of nutrient absorption; however, the absorption rate is greatest in new root growth (root tips), which usually are white in color. The period of greatest nutrient uptake coincides with the period of maximum root growth. Depending on the year, this would be from about March through October in New Mexico, but this period always will be shorter in northern New Mexico than in the southern area. Nitrate uptake increases with shoot elongation and remains high until leaf fall; it then decreases sharply from leaf fall to the initiation of root growth.

Annual nitrogen applications are necessary to maintain sufficient nitrogen reserves in the tree. About 80% of the annual nitrogen use is from tree reserves, while only 20% is from the immediate nitrogen application. The later nitrogen is applied during the growing season, the less it is used the year of application, and the greater its contribution the next year. Therefore, nitrogen applied late in the year is stored, mainly in the root system, for use the following year. Nitrogen used during bloom is drawn from nitrogen the tree has stored from the previous year’s application. Shoot growth in late spring or early summer then becomes dependent on external nitrogen supply. In some cases, all stored nitrogen is exhausted by the end of June. In nitrogen-deficient orchards, nitrogen from fertilizers applied during the current season can be absorbed immediately.

Based on these findings, half the recommended nitrogen should be applied during the post-harvest period, to be stored and used early in the following season. The other half should be applied after bloom. (Coarse textured (sandy) soils are an exception to this recommendation because nitrogen fertilizer applied in the fall is subject to leaching.) Foliar application of nitrogen during the season also helps trees. Fall season applications will be absorbed by roots while trees have foliage, and whenever temperatures are above 45°.

Nitrogen rates should be adjusted so young, non-bearing trees grow 24-36 in. per year. The recommended rate is 1/20 lb of pure nitrogen per year of age of tree. To calculate the amount of a given nitrogen fertilizer needed, use the following equation:

Age of tree(years) x 5 = lb fertilizer/tree
% of N fertilizer

Example: Fertilizing 30-year-old trees with
ammonium sulfate (AS) which has 21% N –

30 x 5 = 7.1 lb AS/tree

Other formulas recommend 1/5 lb N (or 1 lb of ammonium sulfate) per inch of trunk diameter.

Nitrogen fertilization rates for mature, heavy-bearing trees fluctuate from 150 to 200 lb of nitrogen per acre, or 750-1,000 lb of ammonium sulfate per acre. Annual shoot (terminal) growth should be around 6-10 in. per year. If growth patterns are higher or lower, nitrogen rates should be adjusted accordingly. A general recommendation for apple trees is listed in table 1.

Ammonium sulfate is the nitrogen formulation most recommended for orchards in New Mexico because it acidifies the soil somewhat. Although temporary, this action can make available some minor elements for use by apple trees.

Table 1. Amount of N recommended for apple trees.
Age (years) N per tree or per acre
1 None*
2 1/4 lb/tree if growth is poor
3-5 1/4-1/3 lb/tree
6-7 1/2 lb/tree
over 7 150-200 lb/acre
* When leaves have appeared and young trees are growing
vigorously, broadcast monthly applications of N at the rate of
0.05 lb N per tree (0.25 lb ammonium sulfate).

Any formulation of nitrogen fertilizer is converted to ammonium, then to nitrate, before it is absorbed by the tree’s root system. Nitrates are water soluble and can be easily leached out in irrigation water. Generally, tree utilization of surface broadcast nitrogen fertilizer is low; thus, good fertilization practices are needed to prevent nitrogen losses through leaching. The best way to apply nitrogen and other fertilizers is through drip irrigation, where nutrients are carried close to the root system and recommended rates can be evenly distributed throughout the season. Another good way to incorporate nitrogen into the soil is by injecting liquid fertilizers into the soil; several applications are needed during the year to take full advantage of this system. Surface broadcast application of nitrogen and other nutrients, with subsequent soil incorporation by discing, will always have some losses, first through volatilization, then through leaching. Splitting fertilization rates throughout the year may prevent most leaching losses, but may not be practical.

Potassium (K)

Potassium deficiency is not common in New Mexico or in the southwestern states, mainly because the clay contained in soils releases enough potassium for tree use. In many cases, apple trees’ perennial root system permits absorption of enough nutrients from soil that would be deficient for annual or seed crops. Apple trees growing in sandy soils, however, usually require potassium applications. Leaf analysis will help determine if potassium fertilizer applications are needed. Potassium sulfate (44% K ) is preferred over potassium chloride (muriate of potash) to avoid chlorine toxicity that can occur in low-rainfall areas. Mild potassium deficiency is similar to nitrogen deficiency, causing yellowish-green leaves. A severe deficiency will cause foliage necrosis, especially with scorched leaf margins, similar to soil salt build-up symptoms. Apply 150-200 lb of potassium per acre every other year if a deficiency occurs.

Although no specific research has been conducted, it is believed potassium and phosphorus fertilizers can be soil-incorporated before planting at a rate of about 200 lb per acre. These nutrients will be spread throughout the soil and be available for root uptake for several years. Higher amounts are needed when a cover crop or sod is present.

Phosphorus (P)

Fruit trees, including apples, have not responded to phosphorus fertilization, regardless of soil or leaf analysis results; therefore, no phosphorus fertilization has been recommended in the past. Furthermore, the high pH in New Mexico soils makes soil-applied phosphorus fertilizer immobile, and it will not move down the soil profile more than 1 in. per year. As with potassium, the extensive and perennial root system of apple trees tends to absorb enough soil phosphorus to fulfill tree requirements. Whenever phosphorus deficiencies occur, they appear on the shoots, petioles, and leaves. The shoot growth appears slender, petioles of the leaves are somewhat upright, the leaves may be smaller than normal, and they tend to be dark green with reddish or purplish tinting of the midrib and larger veins.

Sources of phosphorus fertilizer for apple orchard use have always been superphosphate or the formulation 18-46-0 (N-P-K). Unfortunately, phosphorus fertilizer will not travel down the soil profile in basic (calcareous) soils. However, research in Washington state with monoammonium phosphate (MAP) fertilizer has shown excellent responses in apple orchards, especially in low-vigor trees. This fertilizer is highly soluble and travels down to the root system, making it available for uptake by the trees. Applying 200 lb of MAP about every 2 years will improve apple trees’ growth and production.

Iron and Zinc (Fe, Zn)

For the most part, iron and zinc are found in sufficient amounts for tree needs in New Mexico soils; however, calcareous soils (pH > 7.5) render iron and zinc nutrients unavailable for tree uptake. Bright or pale yellow foliage (iron chlorosis) with a network of green veins identifies iron deficiency. Zinc deficiency is characterized by small leaves and short internodes, making all the foliage in a shoot clump together, appearing like a rosette or lion’s tail. In acute deficiencies some necrotic (dead) spots between leaf veins also can be seen. Symptoms of iron chlorosis usually appear with flushes of new growth; zinc deficiency appears in the middle of the season. In some instances, twigs die back after the first year.

Foliar sprays are recommended to correct this problem. Chelated forms of iron and zinc have been successful. Although such sprays are expensive, they are less likely to cause leaf burning. Zinc and iron sulfate also work when combined with foliarly formulated urea (uran 42%). Sometimes it is necessary to include a water buffer in the solution, which neutralizes the water and helps the chemical be absorbed better by foliage. Usually two sprays are required to correct iron deficiency. Apply the first about 4 weeks after bloom and the second about 3 weeks later.

Zinc may be applied in the fall as a post-harvest application, but the most effective time for application is in the spring before buds open. Higher rates can be used at this stage than later in the season. Spray at or before green tip. Fall applications may be needed where deficiencies are difficult to correct; both applications, post-harvest and spring, may even be needed.

Chelated forms of zinc and iron must be used for soil applications. These formulations dissolve slowly in the soil and can be used by trees before being tied up by soil particles. In high-pH soils, iron and zinc sulfate are quickly transformed to unavailable forms and cannot be taken up by roots. Though chelated formulations of iron and zinc are more expensive than sulfates, they are more effective. Chelates usually help overcome zinc and iron deficiency problems for more than one season, but tree response is slower. Seques-trene 330 Fe has been the best chelated source for iron.

General Guidelines

Annual soil tests are recommended for apple orchards to monitor salt build-up and nutrient (N, P, K) accumulation throughout the soil profile. Minor elements need not be tested. Topsoil (1-1/2 ft) and subsoil (1 1/2-3 ft) should be tested separately. Leaf (tissue) analysis is recommended once or twice a year, if possible, to indicate nutrient uptake by the trees. Several years of tissue analysis will show the trend followed after a given fertilization program. For accurate results, sample 60-100 leaves from the current year’s shoot growth in July. Collect leaves from shoulder height at the tree’s periphery, using leaves from the middle of the current season’s shoot. Sample the same orchard area and the same variety every year. Select only healthy leaves with no spray, insect, or disease damage; sample problem trees separately.

Incorporating manure into orchard soil can also add needed N, P, K. One ton of manure contains around 10 lb N, 5 lb P, and 10 lb K. Manure also increases the soil’s organic matter content. Organic matter is a transitory part of the soil that is continually decomposing and must be replaced regularly. When organic matter is lacking, clay (heavy) soils become physically difficult to manage, as water intake and aeration is reduced because of soil compaction. Sandy soils without organic matter lack body and the capacity to hold water and nutrients.

Cover (green) crops can also be used to increase soil organic matter. Legumes (beans, clover) also incorporate some nitrogen into the soil. When a non-legume cover crop is plowed under as a green manure crop, it is recommended that 30 lb N be applied for each ton of material to speed up decomposition.

New Mexico State University is an equal opportunity/affirmative action employer and educator. NMSU and the U.S. Department of Agriculture cooperating.

Reprinted May 2001
Electronic Distribution July 2001

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