Citrus - all articles

Crop load determines fruit yield and size and a too high fruit number can result in small fruit. Potassium is the key driver of fruit size and alongside nitrogen is required in large quantities throughout fruit development and growth.

A balanced nutrition with macro and micronutrients will help to improve citrus yield through increasing fruit weight. It is important to make sure that nutrients are not limited during early and mid fruit development.

Citrus fruit number needs to be carefully managed and a strong supply of virtually all major and micronutrients is critical to fruit set and fruit number. Application of fertilizer prior to flowering and then through to fruit set and early fruit fill is critical to maintain high numbers of fruit per tree.

Peel thickness requirements vary depending on the citrus type and market needs. Thicker peels provide higher levels of oil extraction and offer a greater resistance against pests and better shelf life. Tailoring your crop nutrition plan will help to manage a desired citrus peel thickness.

Peel splitting is often caused by extreme fluctuations in soil moisture as well as temperature and humidity.

Creasing - the occurrence of narrow sunken furrows on the rind surface which makes processing more difficult as the peel disintegrates and is difficult to separate from the pulp and juice. Plugging - the removal of the peel in the stem end area of the fruit leads to increased incidence of post-harvest

Good crop nutrition, particularly with calcium and potassium, will maintain the integrity of the peel, helping to reduce the incidences of blemishes.

Albedo breakdown is the loss of cohesion in the cells if this white layer under the skin and any stress imposed on this as a result of expansion of the pulp can lead to rotting of this layer. It is also associated with creasing in the fruit. Good nutrition - particularly with calcium - helps to minimize breakdown of albedo tissue.

The TSS content of the fruit is usually obtained from assessing the degrees Brix of the fruit. It is important that the grower aims to produce an acceptable balance of TSS and fruit acidity (see TSS/Acid ratio).

During the ripening process fruit acids are degraded, the sugar content increases and the sugar/acid ratio reaches a higher value. Crop nutrition can influence citrus fruit acidity.

Vitamin C helps the body maintain healthy tissues and strong immune system and a cup of orange juice can contain almost 100mg of the vitamin. A balanced crop nutrition can help growing fruit with higher ascorbic acid (Vitamin C) content.

The TSS/Acid ratio is a key characteristic determining the taste, texture and feel of fruit segments. It is the sugar/acid ratio which contributes towards giving many fruits their characteristic flavor. It is also an indicator of commercial and sensory ripeness.

Juice content is particularly important in processed oranges but also in fresh fruit. A crop nutrition program - backed by good irrigation and water supply to help stimulate nutrient uptake during fruit production and improve the juice content is important.

Citrus blight disease results in the wilt and decline of trees in groves. Although crop nutrition cannot eradicate the effects or control citrus blight there is increasing evidence that nutrition strengthening the tree can help mitigate the disease effects.

Root rot, due to Phytophthora spp., can be controlled by systemic fungicide use. However, good crop nutrition that helps maintain root health and productivity will also help restrict the disease's development.

HLB, also known as citrus greening disease, is fatal for citrus trees. Once a tree becomes infected, there is no cure and it will die.

Citrus trees that lack apical dominance tend to grow in a more chaotic and less controlled way. Where citrus trees lose their apical dominance and send out multiple shoots, check for boron deficiency.

As citrus trees mature the upper foliage shades out the lower leaves, defoliation can occur and branches and twigs may die. Micronutrient deficiency may be another factor and needs to be checked.

Gum formation in the pockets on the trunk or branches of citrus trees is typically due to a Phytophthora spp. The wood beneath the blister shows a pink-orange color and it can be exacerbated by freeze damage, high water tables and salt accumulation.

A healthy grove is the key to consistent, high yields of quality fruit. Nutrient imbalances are often reflected on the citrus leaves. Any leaf disorders need to be checked and corrected.

Your citrus require the right nutrients, at the right time, to achieve the best results possible. Click here for an overview of the role of nutrients by citrus growth stage.

The aim of any grower is a high yielding, quality crop that meets the needs of the end user. There are a large number of agronomic factors which can influence this, many are within the control of the grower, under given climatic and soil conditions.

Nitrogen is a key component of enzymes, vitamins, chlorophyll and other cell constituents, which are essential for crop growth and development. Therefore, nitrogen is one of the most important nutrients needed for high citrus crop yields.

Phosphorus is a component of nucleic acids and lipids and is important in metabolism, energy transfer, and photosynthate transport during citrus production.

Alongside nitrogen, potassium is one of the most important nutrients for citrus production. It is needed for enzyme activation, cell division, photosynthesis, photosynthate transport and osmoregulation.

Calcium is a key component of cell walls and also has a direct influence on the regulation of enzyme systems, phytohormone activities and nutrient uptake.

Magnesium is needed for many processes in the citrus tree, particularly chlorophyll production.

Sulfur is an important component of enzymes and other proteins, and is required for chlorophyll formation in citrus production.

Boron is involved in various enzyme systems and in carbohydrate metabolism and translocation. Boron, like calcium also has an important role in cell structure and cell wall integrity.

Copper in citrus affects photosynthesis, plant protein production, pollen viability and therefore fruit set, respiration and water use efficiency.

In citrus production, iron acts as a catalyst in oxidation/reduction reactions; is involved in respiration; photosynthesis; and the reduction of nitrate and sulfate. It is also a co-factor in many enzymes.

In citrus production, manganese is involved with photosynthesis, efficient use of N, protein metabolism and enzyme activation.

Molybdenum is essential for nitrogen metabolism in citrus production.

Deficiency of zinc significantly reduces citrus growth and yield potential.

Yara's CompleteCitrus Newsletters represent many years of knowledge with concentration on Florida citrus nutrition. The goal is to provide citrus growers with the best available information with which to manage their production optimally, with minimum environmental impact.

Yara's newsletter dedicated to help California citrus growers to produce the best citrus possible with a balanced crop nutrition approach.

Elaborated by our specialists, Yara's fertilizer program for citrus can help you achieve excellent crop performance.