Apple - all articles

Yara's apple crop nutrition program can help you achieve excellent growth and maximize the yield and quality of apples.

Fruit number in apple trees results from a variety of factors, including planting density, orchard system, pruning and thinning practices and also crop nutrition. The desired fruit size should be considered when managing crop load since allowing too many fruits to remain on the tree will result in smaller fruits and reduce tree vigor.

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. Total Soluble Solids (TSS) is therefore of extreme importance to measure the quality of apple.

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 is more likely to occur in apples exposed to heat and sunlight. Inadequate supply of calcium is a major contributing factor.

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. It is also associated with poor calcium content in the fruit. A balanced crop nutrition can help avoid sunburns.

Many disease-causing pathogens (fungi, bacteria, viruses and nematodes) attack apple trees. Damage to apple trees reduces productivity and increases susceptibility to winter injury or attack by additional pests.

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.

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. In addition, a significant proportion of nutrients taken-up by the tree are recycled via the soil as a result of annual pruning, fruit thinning and leaf fall.