Leek Production

Leek, scientifically known as Allium porrum, belongs to the same botanical family as onion and garlic. This vegetable possesses a white elongated bulb situated at the lower part of the leaves, which can be enjoyed as a delicious and refreshing ingredient in various dishes such as stews and casseroles. Additionally, the vibrant green leafy tops of leek are highly regarded for their ability to enhance the flavor of soups and stews.

Notably, leeks are a valuable source of essential nutrients. They contain significant amounts of Vitamins A, B6, C, and K, as well as calcium, manganese, and magnesium. These nutrients contribute to various health benefits, including boosting the immune system, combating infections, possessing anti-cancer properties, and providing other advantageous effects.

ECOLOGICAL REQUIREMENTS

Leeks have the versatility to be cultivated in both indoor environments such as greenhouses, as well as in open fields.

They thrive in soils that are well-drained and nutrient-rich, with a high content of organic matter. The ideal pH range for leeks is 6.2-6.8.

To ensure optimal growth, leeks require temperatures ranging from 12 to 25 degrees Celsius.

Additionally, leeks have a preference for abundant sunlight and benefit from exposure to as much sunshine as possible.

FIELD OPERATIONS

Leeks are propagated through seeds, which are initially cultivated in a designated seedbed.

Raising seedlings

Procedure
  • Select a location that is free from weeds and offers good drainage. It is important to choose an area where no crops from the onion family have been cultivated for at least 1-2 years.
  • Create raised beds that are approximately 1 meter wide. This helps with soil drainage and management.
  • Prepare a solution by mixing 10g of LOYALTY 700WDG, 100g of PYRAMID 700WP, and 20ml of OPTIMIZER in 20 liters of water. Thoroughly drench the soil with this mixture. This treatment serves multiple purposes, including eliminating soil pests and diseases, breaking seed dormancy, and promoting uniform germination.
  • Form shallow furrows in the prepared soil.
  • Sow the leek seeds, spacing them around 2.0cm apart, and lightly cover them with soil.
  • Apply a layer of mulch to the bed and ensure the soil is adequately watered.

Within 1-2 weeks after sowing, the leek seeds should begin to germinate.

Transplanting

When the leek seedlings reach a height of 6 to 12 inches, they are considered suitable for transplanting. It is advisable to carry out the transplanting process during the early morning hours, specifically between 6 and 10 am, or in the late evening hours, from 4 to 6 pm. These cooler parts of the day are optimal for transplanting.

Before transplanting, it is important to thoroughly water the nursery bed to ensure the seedlings are saturated. This step helps prevent damage to the delicate seedlings during the transplanting process.

To transplant the leek seedlings, carefully pull them from the moist nursery bed and place them into the main field. Dig holes that are approximately 15cm deep, with spacing between holes set at around 10cm apart. Maintain a distance of 20cm between rows when arranging the holes for transplanting.

Note;

During the transplanting process, it is recommended to trim the roots of the leek seedlings to approximately 5cm in length. Additionally, it is advisable to chop off the tips of the seedlings before transplanting.

To help the seedlings overcome transplanting shock, a solution of OPTIMIZER should be prepared by mixing 10ml of OPTIMIZER with 20 liters of water. The seedlings should be sprayed with this solution, providing them with a protective boost during the transplantation process.

Cultural practices

Irrigation is crucial for leeks as they possess shallow root systems and require consistent moisture. It is important to regularly water the leeks, particularly during dry weather conditions, to ensure they receive adequate hydration.

Mulching is beneficial as it aids in moisture retention and suppresses the growth of weeds. Decomposed mulch gradually releases nutrients into the soil, which are then absorbed by the leek crop.

Weeding is essential as weeds compete with the leeks for vital resources such as nutrients, water, sunlight, and space. Weeds can also harbor pathogens that may harm the leek plants. Since leeks are not strong competitors against weeds, it is important to maintain a weed-free garden to prevent losses caused by weed infestations.

Blanching is a technique that involves adding soil to the trench around the leek stems. This process helps create a dark environment by blocking sunlight from reaching the lower parts of the leeks. Planting leeks in deep holes facilitates the blanching of the stems, resulting in desirable pale and tender portions.

PESTS & DISEASE MANAGEMENT

Pests

Cutworms are caterpillars that reside in the soil and can cause damage by cutting and consuming the stems of young leek seedlings and transplants. Severe infestations of cutworms can lead to complete crop loss.

To address cutworm infestations, it is recommended to drench the soil with either 60ml of PROFILE 440EC or 20ml of PENTAGON 50EC mixed with 20 liters of water.

The onion fly is characterized by its appearance similar to a small grey house fly. The creamish white maggots or larvae of the onion fly feed on lateral roots, tunnel into the taproot, and may even bore into the base of the stem. Infested leaves exhibit a bluish discoloration, eventually wilting, and the affected plants become shriveled and die. The larvae can also be found inside developing onion bulbs, making the plant susceptible to diseases like soft rot.

To combat onion fly infestations, it is recommended to spray either 10ml of KINGCODE ELITE 50EC, 8ml of LEXUS 247SC, or 5g of PRESENTO 200SP mixed with 20 liters of water.

Onion thrips are a significant insect pest of leeks, causing white flecking on the leaf surface and significantly reducing foliage quality as they feed.

To control onion thrips, it is advised to spray either 5ml of ALONZE 50EC, 30ml of PROFILE 440EC, or 40ml of DEFENDER 25EC mixed with 20 liters of water.

The leek moth is characterized by its pale green caterpillars that tunnel through the leaves, leaving whitish-brown streaks and disfiguring the foliage. As more tunnels are created, the leeks weaken and may collapse or die. Mature caterpillars can tunnel into the leek stem, causing extensive damage that may lead to collapse or rotting from within.

To address leek moth infestations, it is recommended to spray either 20g of SINOPHATE 750SP, 10ml of KINGCODE ELITE 50EC, or 5g of PRESENTO 200SP mixed with 20 liters of water.

Diseases

Damping off is a soil-borne disease that primarily affects seeds and seedlings. Infected seedlings may topple over and die due to the breakdown of plant tissues at the soil level, while infected seeds fail to germinate.

To combat damping off, it is recommended to spray CHANCETYL ELITE 800WDG, MILLIONAIRE 690WDG, or drench with PYRAMID 700WP mixed with 20 liters of water.

Downy mildew is characterized by pale-green leaves that eventually turn yellow, collapse, and die. Oval-shaped lesions appear during the pale-green and yellow stage, which can also become susceptible to other diseases. This disease thrives in cool and humid weather conditions.

To control downy mildew, it is advised to spray GEARLOCK TURBO 250WP, FORTRESS GOLD 720WP, or TRINITY GOLD 452WP mixed with 20 liters of water.

Purple blotch infection leads to the formation of small water-soaked lesions with whitish centers, mainly appearing on older leaves. As the infection progresses, these lesions enlarge, turning purplish with light yellow concentric rings on the margins. Untreated cases may cause leaves to turn yellowish-brown, lose their erectness, and eventually wilt.

To address purple blotch, it is recommended to spray COLONIZER 440WP, ABSOLUTE 375SC, or TRINITY GOLD 425WP mixed with 20 liters of water.

White rot is most noticeable under hot and dry conditions, with plants grown in crowded conditions being more susceptible. Infected leeks exhibit yellow leaves, with a white or gray fungus covering the underground base resembling strands of white thread.

To combat white rot, it is advised to spray MILLIONAIRE 690WDG, RIMETA GOLD 300SC, or EXEMPO CURVE 250SC mixed with 20 liters of water.

Leek rust is commonly observed in leeks grown in wet, nitrogen-rich soils with a lack of potassium. Symptoms include orange, powdery spots on older leaves that later turn yellow.

To control leek rust, it is recommended to spray MILESTONE 250SC, MILLIONAIRE 690WDG, or COLONIZER 440WP mixed with 20 liters of water.

Botrytis leaf blight presents as greyish-white, oval-shaped spots on the leaves, often surrounded by a silvery-white halo with uneven margins. In severe cases, the tips of the leaves may begin to die back.

To address botrytis leaf blight, it is advised to spray EXEMPO CURVE 250SC, IPRODE 500SC, or EXPLORER 3SL mixed with 20 liters of water.

NUTRITION & NUTRITIONAL DEFICIENCIES

To achieve optimal growth and performance, leeks require a consistent supply of nutrients.

These nutrients encompass both macro and micro elements, and to ensure a well-balanced nutrition, it is highly recommended to apply both basal and foliar fertilizers.

Basal fertilizers are taken up by the leek plants through their roots and commonly include fertilizers such as DAP, CAN, NPK, and UREA, among others. Mixing these fertilizers with HUMIPOWER at a ratio of 50:1 helps improve nutrient absorption by the plants, stimulates growth, and provides other beneficial effects.

On the other hand, foliar fertilizers are designed to be absorbed through the leaves. They supply both macro and micro nutrients and can include fertilizers like OPTIMIZER, LAVENDER, GOLDCHANCE SERIES, LEGENDARY, PORTEGE GOLD, LAVENDER, and others.

It is important to apply fertilizers at the recommended rate and in a timely manner for optimal results. Following proper fertilization practices ensures that leeks receive the necessary nutrients to thrive and perform at their best.

Deficiencies

The symptoms of nutrient deficiency can vary depending on whether the condition is acute or chronic.

Nitrogen deficiency

As nutrient deficiency progresses, the older leaves undergo a gradual transition from their typical green appearance to a significantly paler shade of green. Eventually, these older leaves become uniformly chlorotic. The young leaves, on the other hand, retain a green but lighter color and may exhibit reduced size.

To address this deficiency, it is recommended to use GOLDCHANCE SUPER GROWTH at a rate of 50g/20l or LAVENDER at a rate of 20ml/20l. These fertilizers can help supplement the lacking nutrients and promote healthy growth in the leek plants.

Phosphorous deficiency

One significant visual symptom of nutrient deficiency is the stunting or dwarfing of the crops. Additionally, there may be a noticeable purpling of the stem, petiole (leaf stalk), and the undersides of the leaves. In severe cases of deficiency, the leaves may exhibit a blue-gray luster, and a brown netted veining pattern can develop.

To address this deficiency, it is recommended to use any of the following fertilizers: GOLDCHANCE SUPER START at a rate of 50g/20l, LAVENDER at a rate of 20ml/20l, PLANT SOUL at a rate of 20ml/20l, LEGENDARY at a rate of 40ml/20l, DIMIPHITE at a rate of 10ml/20l, or GREENPHITE at a rate of 40ml/20l. These fertilizers can help provide the lacking nutrients and support the healthy growth of the leek plants.

Potassium deficiency

In certain cases of nutrient deficiency, some leaves may exhibit marginal necrosis (cell death at the leaf edges) and/or tip burn. In more severe deficiency conditions, interveinal necrosis (cell death between the main veins) can be observed along with interveinal chlorosis (yellowing between the veins).

To address this deficiency, it is recommended to use any of the following fertilizers: GOLDCHANCE SUPER FLOWERS & FRUITS at a rate of 50g/20l, DIMIPHITE at a rate of 10ml/20l, GREENPHITE at a rate of 40ml/20l, or LEGENDARY at a rate of 40ml/20l. These fertilizers can help provide the necessary nutrients to alleviate the deficiency symptoms and promote healthy development in the leek plants.

Copper deficiency

Leaves affected by copper deficiency exhibit curling, with their petioles bending downward. The deficiency can also manifest as a general light chlorosis throughout the plant, accompanied by a loss of turgor (firmness) in the young leaves. Recently matured leaves may display a netted pattern of green veining, with some areas bleaching to a whitish gray color. Additionally, sunken necrotic spots may develop on certain leaves, causing them to bend downward.

To address this deficiency, it is recommended to use BIO DISTINCTION at a rate of 50ml/20l or COLISEUM at a rate of 20ml/20l. These products can help provide the necessary copper and alleviate the deficiency symptoms in the leek plants.

Zinc deficiency

During the initial stages of zinc deficiency, the younger leaves of the leek plants turn yellow, and pitting occurs on the upper surfaces of the mature leaves between the veins. As the deficiency advances, these symptoms progress into pronounced interveinal necrosis (tissue death) while the main veins remain green.

To address this deficiency, it is recommended to use ZINC GOLD at a rate of 10ml/20l. This product can provide the necessary zinc to alleviate the deficiency symptoms and support healthy growth in the leek plants.

Please take note of the following:

  • When conducting foliar sprays using products such as insecticides, fungicides, foliar feeds, or herbicides, it is advisable to mix the product with INTEGRA at a rate of 3ml/20l. INTEGRA acts as a sticker, spreader, wetter, and penetrant, enhancing the effectiveness of the applied product(s).
  • It is beneficial to alternate the use of chemicals, particularly fungicides and insecticides, throughout the growing season of the crop. This practice helps prevent the development of resistance in pests and ensures continued efficacy of the chemicals.
  • Adhere to the recommended post-harvest intervals (PHI) for the chemicals used. These intervals indicate the required waiting period between chemical application and harvest to ensure food safety and compliance with regulations.
  • When applying basal fertilizers and manures, it is advisable to incorporate HUMIPOWER into the mixture. HUMIPOWER serves as an excellent soil amendment and fertilizer blend, contributing to improved soil fertility and nutrient availability.

It is important to follow these guidelines to optimize the effectiveness of the applied products, prevent resistance development, maintain food safety standards, and enhance overall crop productivity.

MATURITY, HARVEST & POST-HARVEST HANDLING

Harvesting leeks is a straightforward process, and they are most enjoyable when consumed fresh.

Typically, leek harvesting can commence approximately 80 days after planting and continue until the entire harvest is complete or adverse weather conditions make further harvesting impractical.

To prolong the harvest period, it is advisable to selectively pick only the leeks that are needed while allowing the remaining ones to continue growing. The unharvested leeks have the opportunity to grow larger and develop a more robust flavor.

Leeks are usually ready for harvest when they reach the size of a finger or pencil, or when they have reached their mature size.

When harvesting leeks, it is important to place them in boxes or containers that allow proper air circulation. Overloading the containers should be avoided.

Immediate precooling is a crucial step after harvesting. This involves rapidly reducing the temperature of the crop to approximately two degrees Celsius and maintaining it at this temperature with a relative humidity as close to 100% as possible. Under these conditions, leeks can be stored for a period of 2 to 3 months.

Lowering the temperature helps delay the elongation and curvature of the leaf sheath, both of which can affect the quality of the leeks. It also results in a reduction in the intensity of the green color, which is an indicator of freshness.

Leeks themselves do not produce ethylene, but they have a moderate sensitivity to this gas. Exposure to ethylene can accelerate softening and contribute to the development of diseases.

During transportation, it is important to maintain relatively low temperatures. Adequate moisture levels should be maintained, while direct light and stacking should be avoided to preserve the quality of the leeks.

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