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Citrus fruits

The foliar fertilization with micro-nutrients (e.g. manganese, iron, magnesium) is well established since many years. 

Foliar fertilizers can be used preventive as integrated part of the fertilizer strategy or if it comes to an undersupply with nutrients and visible symptoms. The leaf analysis can help to analyze and recognize the availability for each element.

 

Nutrient availabilty

Many parameters in the soil can limit the availability of nutrients – high pH-values can block micro-nutrients, low pH-values can block macro-nutrients. But also dry and cold weather conditions, soil texture and some nutrient antagonism (e.g. oversupply with potassium vs. magnesium and calcium) can lead to a deficiency of nutrients.

Specific requirements for citrus fruits

Citrus fruits are susceptible to iron chloroses. An iron deficiency will be visible by yellowness of the youngest leaves with dark veins. Different paramters, e.g. soil structure, moisture and pH value will influence the iron availability. The foliar fertilizer Lebosol®-Eisen-Citrat GOLD – containing iron and manganese - will enhance the iron and manganese supply and availability. For better spreading and uptake, the product is containing amino acids as well.

Fruit quality and shelf life

The K-/CA-relation is important and affecting the fruit stability: oversupply with potassium is limiting the uptake of calcium which leads to an undersupply with calcium.

A sufficient availability of calcium in the soil doesn’t mean a sufficient availability for the plant because of the calcium transportation characteristics. Lebosol®-Calcium-Forte SC, free of chloride, will improve the calcium concentration in the fruit and enhance quality and shelf life. Besides that, Lebosol®-Calcium-Forte SC is containing the micro nutrients manganese and zinc as well.

Coloration

Phosphorus and potassium are stimulating the coloration of the fruit. Lebosol®-PK-Max, containing both nutrients, can be applied few times from the beginning of fruit setting to stimulate the coloration and fruit stability.

Leaf spots and early leaf fall

Some varieties are susceptable to nutrition based and physiological leaf necrosis and early leaf fall. This is caused by an undersupply and lack of manganese and magnesium. The combination of Lebosol®-Magnesium 400 SC with Lebosol®-Manganese 500 SC can optimize nutrition and reduce these effects. A further critical element will be Molybdenum.  The symptoms of undersupply in citrus fruits are known as “Yellow spot” (“Yellow blotches”). These oval spots and necrosis are appearing between the vains and can spread up to the leaf edge which is curling up. The foliar application with Lebosol®-Molybdän can optimize the nutrition with molybdenum.

Flowering and fruit setting

Boron in combination with calcium (Lebosol®-Robustus SC), zinc (Lebosol®-Zinc 700 SC) and amino acids (Aminosol®) are crucial for the pollen tube growth, flowering and the fruit setting. These products can be applied before flowering or after harvest. The application of the nutrients boron and zinc  will enhance the calcium absorption, too.

Main recommendations

Aim/Problem Recommendation Time
Treated crops are avoided by furred game 2 l Aminosol® (Aminosol with 2 l water 2 - 3 days beforehand (quantity for 1 ha)) When required
Depositing of reserve substances, regeneration, winter hardiness, flower quality 0,5 l/ha Lebosol®-Zink 700 SC +
2 times 2 - 3 l/ha Aminosol®
After harvesting
Promotion of red top colour, fruit size, fruit firmness 2 - 4 times 5 l/ha Lebosol®-Kalium 450 Between the end of fruit drop and harvesting
Improvement in skin quality, calcium transport, flower bud quality 2 - 4 times 2 l/ha Lebosol®-Robustus SC +
2 - 4 times 0,25 l/ha Lebosol®-Zink 700 SC
Fruit set to harvesting
Prevention and alleviation of iron chlorosis, improvement in water transport, leaf quality 2 - 5 times 3 - 7 l/ha Lebosol®-Eisen-Citrat GOLD First leaves fully developed until harvesting (not during flowering)
To prevent premature leaf drop; increased vitality, leaf quality, photosynthesis rate 2 - 4 times 3 - 5 l/ha Lebosol®-Magnesium 400 SC End of flowering to harvesting
Increase in fruit firmness, storage stability and resilience 4 - 6 times 5 - 8 l/ha Lebosol®-Calcium-Forte SC End of flowering to harvesting
Increasing stress tolerance 2 - 3 l/ha Aminosol® End of flowering to harvesting, at stressed sites
Improvement in leaf quality, photosynthesis rate, N efficiency 2 - 4 times 1 l/ha Lebosol®-Mangan GOLD SC From the end of flowering to the end of fruit drop
Stärkung der Widerstandskraft gegen Krankheiten 2 - 4 times 2 - 4 l/ha Lebosol®-Kalium-Plus Green buds to the end of flowering
Boosting of the resistance of the flowers to frost, yield 5 l/ha Lebosol®-Kalium 450 +
1 l/ha Lebosol®-Robustus SC +
1 - 2 times 2 l/ha Aminosol®
From green buds before frost
Improvement in flowering quality, fruit set, calcium transport, fruit quality, colouration 2 times 2 l/ha Lebosol®-Robustus SC +
2 times 0,25 l/ha Lebosol®-Zink 700 SC
White buds to beginning of flowering
Promotion of fruit set, fruit size and colouration 2 times 5 - 7,5 l/ha Aminosol® Green and white buds
Improvement in effectiveness and tolerability of plant protection products 150 - 300 ml Aminosol® (in 100 l spraying water) With plant protection products