Advice on fertilizer application on apples

Nutrient deficiencies can greatly affect the performance and productivity of apple trees. When practicing organic farming, most of the fertilisers used are organic, although small amounts of chemical fertilisers are important. Apple trees require various micronutrients in high levels at different growth stages such as Calcium, Nitrogen, Potassium, Phosphorus, Sulphur, and Magnesium. Besides, they require small traces of micronutrients like Molybdenum, Iron, Cobalt, Silicon, Copper, Zinc, Manganese, Sodium, Boron, and Chloride. Nitrogen is required in large amounts in the early stages and when the trees are growing vigorously. During the flowering and fruiting stage, NPK formulations with a high potassium percentage should be applied or sprayed.

Some indications of nutrient deficiencies in apple plants include:

• Slightly red leaves indicate lack of nitrogen.

• Yellow and green patches on fruits is an indication of potassium deficiency.

• Corky areas on apple fruits indicate boron deficiency.

• Curling backward of leaves is an indication of phosphorus deficiency.

• Deformed fruits.

The amount of fertilisers required by apple trees varies depending on the soil fertility, manure applied, and the growth stage. Several things can happen when incorrect amounts of fertilisers are applied.

For instance, excessive application of fertilisers makes the plants concentrate on producing a lot of shoots and leaves instead of fruits.

Failing to use fertilisers or applying extremely little fertilisers can lead to nutrient deficiencies, stunted growth, and poor health. Besides, the plants under-perform and their ability to fight pests and diseases reduces.

Know when to apply

• Fertilisers should be applied three times per year.

• The first application should be done before flowering.

• The second application should be made after flowering.

• The third application should be done a month later

However, in the early growth stages, and during vegetative growth, fertilisers can be applied at different times of the year depending on the nutrients required. Fertilisers should, however, be applied at controlled rates. Manure and other organic products should be applied regularly to keep the soil healthy and fertile.

Mulching, especially young plants, minimises the growth of weeds, enhances the soil texture, increases the organic matter, minimises water loss through evaporation, and increases soil micro-organisms.