Originally Published In The Deseret News -- Wednesday, February 19, 1997
The Best Time To Add Nutrients To Orchard Is During The Next Few Weeks.
Larry Sagers Is A Horticulturist With The Utah State University Extension Service.
The backyard orchard is a popular spot come harvest time. Nothing beats the taste of tree-ripened fruit. Growing it in the back yard allows us to select the varieties we want and harvest them at the peak of perfection. Unfortunately, fruit does not grow without effort.
Three major fruit-growing tasks are fertilization; pruning and training; and pest control. The next three columns will cover those subjects. All tasks must be done correctly and in a timely manner to harvest the fruits of your labors this season.
Nutrition is vital for growing large, high-quality fruit. The trees require the right amount of nutrients at the right time. The best time to add nutrients is during the next few weeks so they are available as the plants start to grow.
There are 14 essential soil-supplied nutrients. Nitrogen, phosphorus and potassium are primary nutrients. Trees need these in the largest amounts. Sulfur, calcium and magnesium are secondary nutrients and are needed in intermediate amounts. Micronutrients are needed in only very small amounts. These include iron, copper, zinc, manganese, molybedenum, boron and chlorine. Nitrogen, in particular, is needed at the first of the season to provide nutrients as the trees start to grow.
Fruit trees need all the nutrients mentioned to yield satisfactory produce. All are normally available in the amount needed for fruit trees in rich garden soils. Trees absorb them in the amount needed to produce the crop. Utah soils are well-supplied with most of the elements that fruit trees need. Consequently, most printed recommendations for tree fertilization written for other areas do not apply to our soils.
Nitrogen is very temporary in the soil. The nutrient recycles itself in many different forms. From the gas in the air it is converted through many different compounds, including those that nurture the plants. Because it readily leaches and converts back to the gaseous form, it has to be added frequently.
The need for other nutrients is often misunderstood. Trees have an extensive perennial root system that allows them to absorb adequate nutrients, so such things as phosphorus and potassium are usually not added.
Typically fruit trees are fertilized based on their growth during the previous year. Look at the past season's growth. Growth starts at the bud scale scar (an annual growth ring) and extends to the tip. The last year's wood is a brighter red or yellow than the older wood. Two-year and older wood has heavier bark and has developed a dull or grayish appearance.
Measure the length of shoots from previous years on several branches and determine an average length. The accompanying table suggests the average length of shoot growth for healthy trees. Increase the amount of nitrogen fertilizer if the shoot growth is below average and decrease the rate if the growth is above average.
The chart notes the average shoot growth in inches. Pears frequently do best without added fertilizer because of fireblight. Young, vigorous growth is more susceptible to this bacterial disease.
The second part of the chart lists the recommended pounds of nitrogen per fruit tree.
Scatter the nitrogen fertilizer on the soil under the drip line or branches of the tree. Do not apply any against the tree trunk. Melting snow and spring rains will carry the nutrients into the root zone.
Iron is the most serious micro-nutrient problem. Typical symptoms include yellow leaves with bright green veins. Trees that showed this problem last season need treatment early in the spring with an iron chelate. Do not overwater the trees, as this causes serious problems that are difficult to correct later in the season.
Careful fertilization will produce larger, higher-quality fruit to enjoy this summer and fall. Do not apply more than the recommended amounts as this will affect the availability of other nutrients and cause varying nutritional problems.
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ADDITIONAL INFORMATION
Average shoot growth in inches
............................Young trees......Bearing trees
Fruit trees to 6 years old over 6 years old
Apple, dwarf, semidwarf 10 to 20 4 to 8
Apple, standard, spur types 10 to 20 6 to 10
Peach, nectarine, apricot 10 to 24 8 to 15
Sour cherry, plum 10 to 20 8 to 12
Nitrogen - Pounds per tree
Age of fruit tree Actual nitrogen Ammonia nitrate Ammonia sulfate
1 - 3 years 1/4 - 1/2 3/4 - 1 1/2 1 1/4 - 2 1/2
3 - 8 years 1/2 - 1 1 - 1 2/3 2 1/2 - 5
Mature trees 1 min. 3 min. 5 min.
Large apple, cherry 1 1/2 - 3 4 1/2 - 9 7 1/2 - 15
© 1998 Deseret News Publishing Co.