It is known that palm trees are one of the strongest trees tolerant of soil salinity, irrigation water and lack of fertilization, but this affects the degree of growth of trees, as well as the productivity of horse trees for fruits.
Therefore, full care must be taken to know the appropriate needs of palm trees, whether soil salinity and also the salinity of irrigation water, in addition to the need of palm trees for nutrients from nitrogen, phosphorous, potassium, magnesium and sulfur, in addition to the rare fertilizer elements such as iron, zinc, manganese, copper, boron, molybdenum and other trace elements. Which palm trees need in order for the trees to grow well and produce an abundant crop.
Lack of fertilizer elements on palms
First: The salinity suitable for palm trees:
It is known that palm trees can withstand high salinity in time, high soil salinity, and also the salinity of irrigation water severely affects the growth of trees and fruit production.
Palm trees may tolerate very high salinity between 4000-6000 parts per million, but the production of fruits stops if the roots go deep in a land whose salinity exceeds 6000 parts per million, which leads to a halt in the growth and fruits of trees just as it leads to yellowing of the fronds and then completely dry.
The major and minor fertilizing elements needed by palm trees:
Palm trees bear the lack of various fertilizer elements, whether major elements of nitrogen, phosphorous, potassium and magnesium, but some nutrients in the soil may turn into a non-absorbable form, especially in sandy lands that have less ability to exchange cations.
But in fact, despite the ability of palm trees to resist malnutrition, to a certain extent, the trees soon show distinctive disease symptoms, and their production of fruits decreases significantly due to the importance of these elements in the growth and fruits of trees.
Where the palm trees need, in addition to water and air, some of the nutrient elements for the necessary nutrients that they derive from the soil.
But it needs some of them in large quantities, such as nitrogen, phosphorous, potassium, magnesium, sulfur and calcium, in addition to the fertilizing and micro-nutrient elements for trees such as iron, zinc, manganese, copper, boron, chlorine, molybdenum and the last trace elements.
As the lack of nutrients nutrients for palm trees leads to a halt in the growth and fruits of trees with the emergence of many diseases that severely affect the efficiency of trees.
Palm trees vary in the quantities they need of different fertilizer elements between different varieties, so the fertilizer elements must be available in any form to obtain good growth and good fruits as well.
But sometimes an imbalance may occur in the concentration of nutrients in the agricultural soil, and some of them are reduced to a degree that severely affects the growth and fruiting of palm trees, for the following reasons:
1- There may be a deficiency of these elements in the soil.
2- There may be nutrients in the soil, but they are not absorbable and therefore trees will not be able to benefit from them.
Therefore, a laboratory analysis of the elements in the soil must be conducted, as well as the nature of each element in it and the image in which it is found.
3- The fertilizer element may be present in the soil in sufficient quantities, but at the same time the trees may not be able to absorb it due to a pathological injury to the roots, which makes them unable to absorb these elements.
4- There may be some nutrients in the soil, but trees cannot benefit from them, when there is a contradiction between these elements and other elements, which prevents these elements from being absorbed by the trees.
Therefore, the deficiency of these elements can be corrected by adding them to the soil if there are no other factors that hinder the trees from absorbing and benefiting from them, otherwise it can be added by spraying.
In order to determine the type of element that has a deficiency, one can be guided by the nature of the apparent symptoms on the trees, but a chemical analysis of the soil and irrigation water must be conducted, as well as the analysis of healthy and infected palm leaves so that this element can be accurately determined.
The following are some of the physiological diseases of yellowing palm leaves.
First: Yellowing of the lower old palm fronds (large fronds):
1- Early yellowing of the lower leaves of palm trees occurs, which affects their efficiency in the process of photosynthesis and making food necessary for the growth and fruition of trees.
2- There is also a deficiency of some nutrients such as nitrogen, magnesium and potassium, which causes the yellowing of palm leaves (fronds), as follows:
Yellowing due to nitrogen deficiency:
Nitrogen deficiency causes the following symptoms.
1- Yellowing of large, aged leaves first, then followed by other leaves if the deficiency is severe. Usually, yellowing starts from the top of the frond towards its base, and the yellowing starts from the tops of the wicker towards the base in the form of the letter V where the edges and sides are green, but after that it does not Soon all its tissues yellowed.
2- Palm trees respond to nitrogen fertilization if it is done early, as the leaves are green after treatment, and it is preferable in this case to divide the nitrogen fertilizer in batches during the growing season at a rate of 1 – 1.5 kg / tree in each batch.
Yellowness caused by magnesium deficiency:
1 – Magnesium deficiency usually occurs in sandy lands because of its easy leaching. Magnesium deficiency may occur as a result of an increase in the amount of calcium and potassium in the soil, which causes symptoms of magnesium deficiency despite its presence in the soil.
2- Yellowing appears on the leaves due to the deficiency of magnesium, as the large leaves start from the top to the bottom, but the wicker bases around the middle vein of the leaf
remain green and the yellowed wicker tops may die after that.
3- When fertilizing with magnesium, the yellowing leaves.
