Apple

Yara's apple fertiliser programmes can help you to achieve excellent growth and maximise the yield and quality of apples

Yara's fertiliser programme for pears can help you to achieve excellent growth and maximise the yield and quality of pears

Fruit number in apple trees results from a variety of factors, including planting density, orchard system, pruning and thinning practices and also crop nutrition.

Size is a critical characteristic for grading apples. A minimal size, determined by the diameter of the equatorial section, is required on all grades. An evenly shaped and sized fruit is desired for the fresh market and also for canning. Apples size is greatly influenced by pruning and thinning practices and also by crop nutrition.

Apple weight is an important element for increasing yields. Provided that a desired quality is maintained, the aim of growers is to produce heavier fruits. Crop nutrition plays an important role on increasing apple weight.

Colour of the skin is a very appealing apple quality to consumers. Therefore, growers generally seek to improve fruit colouration. Crop nutrition can help to achieve the desired appearance.

Over-use or late applications of nitrogen reduces apple firmness, potentially resulting in more damage in transit and storage, and a reduced shelf life.

Apple flavor and taste are related to the level of soluble solids in the fruit, which are mainly sugars.

Bitter pit is a physiological disorder associated with low levels of calcium in the apple tissue, which reduces apple quality and marketability.

Lenticel are slightly sunken blotches that result in underlying tissue drying out and becoming brown and spongy. Its occurrence is more prominent than that of bitter pit. Lenticel blotch is associated with hot summers, late harvests and excessive use of nitrogen. Pitting is always associated with a lenticel.

Water core develops in mature apples when the sugar sorbitol is translocated into the fruit faster than it can be assimilated. The area surrounding the core becomes water-soaked or translucent and may appear glassy and hard.

Internal breakdown in apple is the breakdown of internal tissues resulting from fluid oxidation. In severe cases, tissues become spongy. It can be associated with intense water core disorder, cold storage, and boron and phosphorus deficiencies. A good crop nutrition can help to minimize internal breakdown incidence in apples.

Sunscald or sunburn in apples accounts for yellow or flushed areas on the fruit skin due to direct sun damage often following a period of cooler, cloudy weather. In severe instances, the scald damage turns dark while the fruit is still on the tree, with the underlying tissue becoming spongy.

Many disease-causing pathogens (fungi, bacteria, viruses and nematodes) attack apple trees.

Plant nutrients are essential building blocks of crops. In order to obtain high apple yields it is important to achieve the right balance of fruit number on the tree. High yields are obtained on freely drained soils where water is not limiting.

Here you find an overview of the role of nutrients by apple growth stages.

The aim of any producer is a high yielding, high quality crop that satisfies 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 growing systems, climatic and soil conditions.

There are hundreds of apple varieties, but five currently dominate world production: Fuji, Golden Delicious, Delicious, Granny Smith and Gala. However, in a given region or country there maybe other equally important cultivars.

Choice of rootstock governs tree size and the efficiency of nutrient uptake. Optimum planting density depends upon rootstock, cultivar and likely pruning strategy.

During leaf and shoot development, nitrogen, phosphorus, potassium and zinc concentrations fall. Others, most importantly calcium, increase over this period.

Apples and pear trees can grow in a wide range of soils from medium textured clays to gravelly sands.

In established orchards, dry-applied fertilisers can be broadcast across the soil surface or banded underneath trees.

Around 100 million tonnes of pome fruit are produced annually worldwide across 7.3 million hectares.

There are many different varieties of apples and pears.

Calcium is critical in pears, and fruit concentrations need to be double that acceptable for apple. 10mg/100g fresh weight at harvest is the accepted norm in European pears.

Most nutrients are stored and retained as reserves in tree buds, bark and roots. These are then remobilized after winter to fuel leaf growth, flower bloom, fruit formation and growth.

Alfalfa greening is a disorder which causes dark-green, slightly sunken spots on the skin of pears. A balanced crop nutrition is essential to minimize alfalfa greening occurrence.

Nitrogen has a major effect on yield and quality. It is a component of the chlorophyll molecule and involved in nucleic acid synthesis and hence important for cell division and the growth of young tissues (e.g. buds, flowers, leaves). Nitrogen is involved in amino acid synthesis and protein production.

Calcium activates enzymes and is essential for cell division, elongation, and fruit growth. It stabilizes and ensures permeability of the cell wall, protecting it from degradation by enzymes.

Magnesium is a key constituent of the chlorophyll molecule; usually 15-20% of the tree’s Mg total is found in the chloroplast. It is also involved in various biochemical functions including activating enzymes involving phosphorylation, and protein synthesis.

Sulfur is a key component of amino acids, proteins and coenzymes. Thus, lack of sulfur will inhibit protein synthesis and reduce tree growth.

Copper is required for chlorophyll synthesis and is a constituent of enzymes responsible for the reduction of molecular oxygen.

Boron is involved in cell wall formation, stabilization and lignification, and xylem differentiation. It is needed to ensure normal development of new tissues from roots to flowers and fruit.

Iron is required as a precursor to chlorophyll formation and in a number of important plant enzymes. Poor supply restricts photosynthesis and, as a result, reduces leaf growth and resultant fruit yield and quality.

Zinc functions in many enzyme systems and biochemical functions including acting as a precursor of indoleacetic acid which is involved in shoot elongation. The micronutrient thus plays a major part in bud development and flowering. Poor zinc supply restricts leaf and bud growth and development, leading to bare bark or rosettes of spindly leaves.