Zaid Crops

Sunflower Cultivation

Botanical name:  Helianthus annuus  
  Family: Asteraceae (Sunflower family)
In Greek “helios” means sun and “anthos” means flower, thus Sunflower. The name is just apt for a plant that turns its flower to face directly into the sun as it passes and also looks like the sun in its yellow rays. Helianthus annuus is a highly variable species that is indigenous to North America.

Climate

The crop requires a cool climate during germination and seedling growth. Seedlings tolerate frosts moderately well until they reach the four to six leaf stage of development. It requires warm weather from the seedling stage up to flowering stage and warm and sunny days during flowering to maturity. High humidity accompanied with cloudy weather and rainfall at the time of flowering results in poor seed set. The amount of linoleic acid decreases with high temperatures at maturity. Sunflower is a photo-insensitive crop, therefore, it can be grown successfully in any season viz., Kharif, Rabi and spring throughout India. It takes about 80-90 days in Kharif, 105-130 days in Rabi and 100-110 days in spring season. Sunflower, unlike most other crops, is not affected with the season and day length. With the exception of freezing temperatures, the sowing of sunflower can be done in any month of the year.

Soil 

Sunflower can be grown on a wide range of soils and tolerates a moderate pH range and some salinity. It thrives best on deep loam soils with good drainage and irrigation facilities. The optimum range of soil pH for this crop is 6.5 to 8.5. It performs better than groundnut in heavy black cotton soils of Karnataka and Tamil Nadu.

Sowing

The seed before sowing should be treated with Captan or Ceresan at the rate of 3 g per kg of seed. Bold and certified seeds should be used. A seed rate of 8-10 kg per hectare is sufficient to ensure good crop stand, Sunflower should be sown 60 cm apart in lines with a plant to plant spacing of 20 cm. The seed should be sown at 3-4 cm depth for better stand. Sowing can be done by corn planter in the furrows. After 10-12 days of germination, extra seedlings should be uprooted to provide a space of 20 cm between plants in rows.

Manures & Fartilizers

Sunflower is an exhaustive crop and responds well to nitrogen phosphorus and potash. A crop of sunflower yielding 14 quintals of grain per hectare exhausts 175 kg N, 65 kg P2O5 and 225 kg K2O from one hectare land. Therefore, it is necessary to add adequate amount of manure and fertilizers in the field of sunflower. Nitrogen is essential for vegetative growth but to improve the seed size and its proper filling and to increase oil content liberal supply of phosphorus is essential. Potash also helps in grain filling and disease resistance. A dose of 60-80 kg nitrogen, 60 kg P2O5 and 40 kg K2O per hectare has been found optimum for sunflower. Two-third quantity of nitrogen and whole of phosphorus and potash should be applied as basal dose at the time of sowing. Remaining dose of nitrogen should be top dressed at the time of second irrigation (flowering stage).

Irrigation

Sunflower is a crop of medium water requirement. Usually no irrigation is needed for Kharif crop. However, one irrigation should be given in case of uneven distribution of rainfall. Pre-sowing irrigation is necessary for Rabi and Zaid crops to get uniform germination and better stand. Rabi crop may be irrigated thrice after 40, 75 and 110 days of sowing which will roughly coincide to four to five leaf stage, flowering and grain filling stages of the crop. Sunflower crop is highly sensitive to water stress between flowering and grain filling stages and at least one of the irrigation must be applied during this period.

Weed Management

Intercultural operations are essential to minimize the competition of sunflower plant with the weeds. Weed-free conditions up to 60 days after sowing results in better yield performance. When the plant attains a knee high stage earthing should be done along the rows. This provides safe-guard against lodging which is likely to occur at heading stage if winds of high velocity blow. Use of Sirmate at the rate of 4 kg per hectare applied as pre-emergence has been found effective in controlling weeds in sunflower crop. If Sirmate is not available use Basalin at the rate of 1 kg a.i. per hectare dissolved in 800-1000 litres of water as pre-planting spray.

Diseases

Category : Fungal

Alternaria leaf blight Alternaria helianthi

Dark brown lesions on leaves surrounded by a yellow halo; lesions coalesce and become irregularly shaped and cause leaves to become blighted; plant becomes defoliated and dies
Cause
Fungus
Comments
Disease emergence favors hot weather and frequent rainfall; fungus may survive in crop debris or on suitable weed hosts; disease can be transmitted through infested seed
Management

Prune out infected leaves; use adequate plant spacing to reduce humidity around plants and promote good air circulation; disease can be controlled by application of appropriate foliar fungicide

Downy mildew Plasmopara halstedi

Death of seedlings leading to reduced stand in field; if seedlings survive they may be chlorotic with thickened leaves; white cottony growth is present on leaf undersides; systemic infection causes stunted plant growth and reduced seed production

Cause
Fungus
Comments
Disease emergence favors high humidity; fungus can survive in soil for up to 10 years
Management

Plant sunflower varieties that are resistant to downy mildew; treat seeds with an appropriate fungicide prior to planting; foliar fungicides are ineffective at controlling systemic infections and are not recommended

Phoma blight Phoma macdonaldii

Symptoms of the disease develop after flowering; large black lesions appear on stem and coalesce to form large blackened areas; dark colored irregularly shaped lesions appear on leaves and flowers; early infections can cause flowers to die; infected plants die prematurely and produce little seed; disease often affects plants in a circular pattern in the field
Cause
Fungus
Comments
Fungus survives in seeds or sunflower debris in the field; disease emergence favors periods of wet weather during flowering
Management

Rotate crop to a non-host (e.g. small grains) a period of 4 years; plant hybrids which are more tolerant of the disease; control stem weevil populations in sunflower fields

Powdery mildew Erysiphe cichoracearum

Symptoms
Powdery white patches which appear initially on lower leaves but which may spread to all above-ground parts of plants; white patches turn gray in color and black fungal fruiting bodies are visible; severely infected leaves may turn yellow and dry up
Cause
Fungus
Comments
Conditions which favor the development of the disease mach those that are favorable for the host plant; disease emergence is favored by periods of high humidity where leaves remain dry
Management

Allow adequate spacing between plants to promote good air circulation around foliage; plant sunflowers in an area that receives full sun for most of the day; remove and destroy all sunflower crop debris after harvest; applications of appropriate foliar fungicides can help control the disease but care should be taken as some labels do not allow seeds from treated plants to be used as food or feed

Septoria leaf spot Septoria helianthi

Symptoms
Water-soaked circular or angular spots on leaves with a greasy, greenish appearance on lower leaves; lesions are usually gray with a darker margin; some lesions may have a narrow yellow border; tiny black fungal fruiting bodies may be present in the lesions
Cause
Fungus
Comments
Little is known about the survival and spread of the pathogen which causes the disease; spores are believed to be spread by splashing water; disease will develop rapidly during periods of moderate to warm weather with high rainfall
Management

Plant high quality seed which is free of diseases; rotate crop away from sunflower for a period of 3 years, especially if overhead irrigation is used; fungicides are rarely required for the treatment of Septoria leaf spot

Verticillium wilt Verticillium dahliae

Symptoms
Lower leaves developing mottled appearance; leaf tissue between veins turns yellow and then brown; infected leaves wilt, dry out and eventually die; stems of plants may become blackened close to the soil line; a cross section of the stem reveals blackened vascular system
Cause
Fungus
Comments
Fungus is soil-borne and enters plants through the roots, invading the vascular system; pathogen can be spread to uninfested fields through contaminated irrigation water or movement of infested soils
Management
Insect-Pest
Pest Management in Sunflower Plants Not many pests bother the sunflower and those that do only wreak havoc in large numbers. The most common sunflower pests include the following:
Sunflower Beetles – Sunflower beetles typically feed on the leaf foliage and in small numbers or older plants may seldom hurt the plants. However, on younger sunflower plants, the first true leaves can be severely damaged or completely consumed.
Cutworms – Cutworms can also damage the leaves of young sunflowers, leaving notches or holes. Wilting may also occur. Again, these are usually not a major issue unless there is a heavy infestation.
Sunflower Borers – Sunflower borers and stem maggots burrow into the stems of sunflower plants to feed. This can quickly kill the vegetation and other parts of sunflower plants, especially in large numbers.
Sunflower Moths – Sunflower moths are one of the most destructive pests to sunflowers, laying their eggs within the flowers. Once the eggs hatch, the larvae move into the flower heads to feed, ultimately destroying the plants. Grasshoppers – Grasshoppers and various caterpillars also enjoy nibbling on sunflower foliage. While rarely a major problem, large numbers can quickly defoliate plants.

Harvesting and Yeild

The sunflower crop is ready for harvest when moisture in seed is 20 per cent. Phenotypic ally the heads are ripe when back of the head turns yellowish-brown. All heads may not be ready for harvesting at one time. Harvesting may, therefore, by done in two or three installments to avoid shattering. The harvested heads should be dried well in sun and then only threshes by beating the centre of the head with a small stick. The commercial crop may be threshed with available threshers by reducing their speed. Further, sun-drying of the seed is desirable before storage or oil.

A good crop of sunflower raised property and nursed appropriately should yield over 20 quintals per hectare.

Storage

After threshing the produce should be throughly dried before storing otherwise in storage it gets affected by fungus and decomposes.

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