Agronomy Advice
April 02, 2020

Fruit crops will benefit from foliar calcium in a wet season

By: Giz Gaskin

After a wet winter many fruit plants may have been growing under saturated conditions for some time. Under these circumstances the application of foliar fed calcium will be advantageous.

Fruit crops benefit from foliar calcium in a wet season
Fruit crops benefit from foliar calcium in a wet season
Foliar fed calcium reduces fruit splitting

Grape and cherry crops often suffer from fruit issues with ‘splitting’ in the fruit after fruit swell pre full ripening, especially in a high-water. This issue in both crops is caused by the same physiological condition of too much water uptake and lack of calcium uptake. Calcium is a key nutrient for strong leaf and fruit growth, its key component of cell walls.


Calcium is an immobile nutrient and is difficult for roots to take up under saturated conditions, as highly mobile nutrients are far more available to root. Further, soil microbes which would normally aid the breakdown of calcium for root uptake perform badly in saturated water due to lack of oxygen. Given the lack of uptake of calcium from root level in wet years, building and keeping good leaf is essential. The leaf can in a wet year provide both functions of photosynthesis and nutrient uptake from foliar feeding of immobile nutrients like calcium.

Soft fruits, especially strawberry and raspberry, also benefit from increased calcium as it both improves the palatability by balancing the acid content and has been known to increase shelf life by as much as one to two days. Important for crops which are known for their very short shelf life of 8 to 10 days. Calcium greatly improves skin strength in strawberry and raspberry.

Micronutrients help manage increased pest and disease pressure

A secondary point to consider in wet years is the increased likelihood of softer leafy growth. More nitrogen less calcium tends to increase this situation, to the benefit of sap drinking insects like aphid. Aphid take advantage of the soft cell walls piercing leaf with the proboscis and extracting the sap. Stronger leaf resists aphid better, in a normal year the aphid would be seen on the newly emerging leaf as they are much softer. Maintaining a good micronutrient regime on crops can limit the impacts of softer growth leading to decreased pest pressure.

As the weather is set to warm up from a saturated soil condition, this year will become as last year, ideal for fungal growth. Fungal pathogens are much hardier of anaerobic soil conditions, needing only warmer temperatures to begin their cycle. Plant site of infection roots, crows and lower stem will be softer in spring due to saturated soil. Combine this with softer leafy growth higher up and the fungal pathogens can land anywhere and have an impact. Expect mildew (downy more than powdery), botrytis and phytophthora (root rot) to be issues this year. The key to these is good husbandry and trying to break up the micro climate which these pathogens love. Foliar feeds like YaraVita SENIPHOS and YaraVita THIOTRAC 300 can further help to keep suppressing fungal pathogens by breaking the microclimate at leaf & fruit level, while maintaining nutrient uptake. Foliar feeding reduces the demand on the roots reliving root stress as soil condition return to a more normal state. As the roots need to get back to better root condition, feeding foliar YaraVita BIOTRAC can help reduce plant stress while at the same time add root stimulation growth from the organic plant enzymes contained with in YaraVita BIOTRAC.

Micronutrient formulation is important to ensure effectiveness

It is important to remember that leaf must be free from deposits if it is to continue to photosynthesise efficiently. A build up of calcium deposits on the leaf will limit the leaf's ability to perform its primary function. Therefore, the calcium feed chosen must be correctly formulated to ensure an even spread. This is particularly important in wet years, when plants can succumb to stress more easily.

As discussed above, in a wet season crops will need foliar calcium application to support nutrient uptake reliving root pressure. The coverage of leaf needed to be uniform to aid efficacy and more importantly reduce deposits building up, blocking photosynthesis. All Yara foliar feeds are tested and formulated thoroughly to make sure they perform through the application machinery and upon contact with leaf spread uniformly, with no build up. This has been demonstrated in on cherry using the Yara foliar feed of YaraVita STOPIT.

stone fruit fertiliser and crop nutrition advice
stone fruit fertiliser and crop nutrition advice

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