Apple Tree fertilizing

Apple Tree Fertilizing and Nutrition Recommendations

Fruit trees are fertilized to make sure continued growth and healthy fruit production. In the orchard, proper application of fertilizer and nutrition helps to maintain the healthy growth and the productivity of the fruit tree. The amount of fertilizers to apply can be based on skin of fruit tree, the colour of leaves or how much shoot growth occurred in the previous season or based on a soil analysis. Apply nutrients based on a soil test analysis conducted by the soil testing lab.

Fertilizing mature apple trees is an important factor and requires lot of efforts and presence of mind in order for the apples to grow and ripen optimally. Apples are very vulnerable to the changing weather conditions, so special care has to be taken. The crucial part is not to grow apple trees but is the maintenance and sustainability of these trees until it reaches maturity. There are many factors why fertilizing apple trees are needed such as the soil pH and the presence of important elements and nutrients, nitrogen, phosphorus and potassium this has to be timely checked.

NPK is the short form for Nitrogen (N), Phosphorus (P) and Potassium (K) which are three most important elements in fertilizing apple trees in order for your apples to survive from the start to the end. There are other important elements in fertilizing apple trees are sulphur, magnesium, calcium, boron, iron, zinc, copper and manganese which could help in bringing the apple trees in its fullest potential. It is also highly recommended that the orchardist must purchase pre-packed fertilizers in fertilizing apple trees with their own fertilizers in order for the sufficient amounts to be distributed equally.

In fertilizing apple trees, it is not only the nutrients are important, but also the amounts and proportions to be given. The distribution of the nutrients in appropriate proportions is a pivotal part in the successful growth of apple trees.

In order to find the deficiency of the fertilizers, through eyes is by looking at the leaves of trees it can tell the story about the health of the tree.

pH and Lime of soil

Orchard soils should have a soil pH of about 6.5 throughout the effective rooting soil profile. Since it is not feasible to incorporate lime into the soil profile of established orchards, soils should be properly limed prior to planting. After pre-plant liming, periodic lime top dress as recommended by soil tests will maintain the proper soil pH.

Matured Orchards

Matured orchards you do not have the option of incorporating your lime. Others have looked at injection of lime around trees in various patterns and by various styles. This seems to be due to the fact that all of the methods tried affected a very small percentage of the soil in the total rooting volume. Concentrating the soil amendment can work well with fertilizer, but does not work as well for lime. Where an established orchard soil requires lime, it is usually best to apply 1 to 2 tons per acre of a good agricultural limestone annually, re-sample the soil in both the 0 to 8 inch and the 8 to 16 inch depths annually until the soil pH is corrected (hopefully at both levels).

Elements in Fertilizing

NITROGEN (N)

There is no single N program that is correct for all orchard situations. Insufficient N results in symptoms and problems similar to many crops.

Deficiency

They include less vigor, light green to yellow-green leaves, less vegetative growth and low yields, as seen in the accompanying picture. While low N can be a problem for most species of tree fruit, excessive N can be equally bad. Young, non-bearing trees will often benefit more from higher N programs than older bearing trees. The goal with young trees is to produce wood and vegetative growth, while the goal with bearing trees is strong yields of high quality fruit.

For Growth

The N requirement of apples can be generally related to the amount of wood in the trees. In other words, larger trees generally require a higher N program than dwarf trees.

Pruning

Heavily pruned trees generally require less N. This relates to the lower amount of wood and foliage present to utilize the N, and the higher “root to shoot” ratio after pruning.

Density of Tree

As a general rule, more trees per acre means more N required. However, where higher populations are coupled with strongly dwarfed varieties, and severe pruning (such as “hedgerow” planting), the grower may find that the N rate required for optimum leaf N levels may not differ significantly from lower populations.

Judging Visually the N Status of Fruit Trees

The most desirable nitrogen management program provides a relatively high N status early in the season to encourage rapid leaf development, fruit set, and flower bud formation, but permits N to decline gradually as the season progresses. This tends to enhance favor, fruit color, and tree hardening. The following factors can be used to evaluate apple N status, but none will substitute for annual leaf analysis.

Color of Fruit

In bearing-age trees, fruit color development is delayed when N levels are too high. If other factors are equal, the percentage of red color is reduced by about 5% for each 0.1% increase in leaf N, This relationship is particularly significant with less highly colored fruit varieties or strains. Yellowing of Golden Delicious fruit shows a similar reduction as leaf N increases.

Firmness and fruit size

These are usually inversely related, and both are influenced by N status. Size generally increases with higher N levels, if the crop load is not excessive, and this tends to result in less firm fruit flesh.

Colour and Firmness

Differences in fruit coloring and/or flesh firmness are also a guide in evaluating N status. Soft varieties and apple crops intended for fresh market (eating apples) have a lower optimum N content than those that are bred to be harder, or are intended for processing.

Biennial Bearing

Some apple varieties have a tendency toward biennial bearing. Nitrogen stress will increase the biennial bearing tendency in many varieties, especially Golden Delicious and McIntosh. Reducing the N in these varieties to enhance color development may trigger the biennial bearing of these and other varieties.

Terminal Growth

Nitrogen is also the major nutrient factor influencing the higher N uptake encourages the tree to produce longer annual terminal growth. This is desirable in new plantings, but not in established, bearing trees. Sufficient vigor is also indicated by annual terminal growth of 8 – 12 inches for non-spur varieties, and 6 – 8 inches for spur varieties.

PHOSPHORUS (P)

The status of an orchard soils P supplying power can be difficult to determine, even with the best soil testing program. Fruit trees are deep rooted and can absorb P throughout a deeper soil profile than annual crops. Therefore they are using soil P that isn’t identified by normal soil sampling. Apple trees also absorb P over a long portion of the year, and most soil test calibration assumes a somewhat shorter uptake period. Of course other soil factors such as pH, temperature, moisture, compaction, etc. (at all rooting depths) also affect P uptake. With all of these complications, it may seem futile to take a soil sample, however it remains a fact that a healthy tree will take up more P from a high testing soil than a low one, so periodic soil testing is still a recommended practice. These Complications with trees illustrate the need for annual leaf analysis, coupled with the ability to apply needed nutrients by foliar, or fertigation methods.

Soil Applications

Phosphorus is nearly immobile in most soils, except over many years, so surface applications of P to an established orchard are not as efficient in feeding a plant. Much of the surface applied P will not feed the current year’s crop. It will instead go into the reservoir of soil P and be slowly released to the crop over succeeding years. However roots that are feeding near the soil surface will utilize any available P resulting from annual applications. All of this leads to the obvious conclusion that when establishing a new orchard, it is very important to correct any soil nutrient deficiencies that may exist. This may be the only practical opportunity that you have to increase the deeper soil fertility. Deep soil fertility is a great aid in times of tree stress.

SULFUR (S)

Sulfur is not often a concern with apples. The most likely exception would be on light colored or sandy soils. Plants take up only the sulfate (SO) form of sulfur. Applications of this form will be immediately available. Elemental sulfur (S) requires bacterial conversion to the sulfate form to become available. This process can take an entire season. Where leaf symptoms or plant analysis confirms the need, soil applications of 30 lb. S/acre (as SO) will correct most problems.

MAGNESIUM (MG)

Magnesium deficiencies in pome fruit are often diagnosed by mean of physical symptoms, a technically utilize foliar analysis. Usually when a deficiency, become visible the tree has already lost growth or yield because it has been deficient some period of time. Visual symptoms usually appears in a older leaves which develops light green blotches between veins often extending to leaves margin These areas turns fawn colour and then dark affected leaves may shed pre-maturely.
Magnesium is one of the essential secondary micro nutrients. It occupies a central position in chlorophyll and therefore plays a important role in photosynthesis process.

CALCIUM (CA)

Apples leaf analysis frequently shows a need for higher Ca levels. Low Ca in the fruit cause several disorders, the major ones being bitter pit, cork spot, and senescent breakdown during storage. Apples are not efficient at obtaining calcium from the soil, and are not especially efficient at trans-locating Ca from the roots to the leaves and fruit. Also, during drought stress, water containing calcium may be trans-located from the fruit back into the leaves, thus reducing the Ca content of the fruit. Because of this, foliar sprays, spraying the fruit directly, and apple dips are commonly used to increase the Ca content of the fruit. Soil applications to crops with identified low leaf or fruit Ca levels do not have a Strong success record, however growers should take the necessary actions to correct soil Ca deficiencies, and add lime to acid soils, because this also affects other aspects of proper crop nutrition and growth. Foliar Ca applications, while effective, are not a substitute for keeping the soil properly limed.

BORON (B)

Boron plays a significant role in pollination success and it plays a role in the trees ability to tarns-locate Ca from the roots to other parts of the tree. It is highly mobile in the soil and supplied primarily by organic matter, so deficiencies are most likely to occur on light colored, coarse textured soils. Deficiencies can contribute to poor fruit set. Boron may be applied to the soil or the foliage with good effect. A complete boron program frequently includes both a soil application to meet the basic need of the crop, plus one or more foliar applications to supply additional boron at critical stages of crop development. Growers and their advisors should be aware that excessive B applications have the potential for direct toxicity to the crop. One sign that B uptake is excessive, is premature fruit maturity, and early fruit drop.

IRON (FE)

Iron deficiencies are primarily associated with high soil pH, and sometimes associated with over-watering, high water tables, poor drainage, or the use of irrigation water high in bicarbonates. If deficiencies occur, evaluate these possible causes and make appropriate changes as needed and feasible.
Soil Application: Soil applications of Fe are not recommended due to the extensive soil fixation of any applied Fe.

ZINC (ZN)

Component or regulator cofactor of enzymes, plant hormones proteins (i.e.. aids in normal growth and fruiting).Data does not indicate strong responses to soil applied zinc, Maintain pH of 6.0-6.5 to reduce likelihood of Zn deficiency.

MANGANESE (MN)

Older and mid-shoot leaves affected first. ‘Herringbone’ chlorosis between main veins. Shoot dieback may occur. Flowering and fruit set are reduced.

COPPER (CU)

Younger and tender leaves are affected first; leaves are stunted or misshapen with irregular margins on it. Whitish mottled chlorosis between veins. Fruit color, quality, and size are affected. Treat foliar application of Cu with caution, as fruit russeting and/or foliage injury possible; do not apply after green-tip. Choose cu fungicides mixture or other Cu containing fungicide for disease control if disease is out of control follow manufacturer manual.