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Agricultural crops :: Oilseeds :: Sunflower
Sunflower Diseases

Downy Mildew - Plasmopara halstedii

Rust - Puccinia Helianthi

Alternaria Blight - Alternaria Helianthi

Charcoal Rot - Macrophomina phaseolina

Sclerotium Wilt or Rot - Sclerotium Rolfsii

Rhizopus Head Rot - Rhizopus sp

Sunflower Necrosis - Tobacco straek virus

Tobacco Streak Virus

Yellow Blotch disease

Leaf Crinkle Disease

Downy Mildew: Plasmoparahalstedii

Symptom
  • The disease spreads rapidly through seeds.
  • Symptoms of the disease are evident as seedling damping off, systemic infection, local foliar lesions and basal root or stem galls.
  • First symptoms are yellowing of the first pair of true leaves.
  • Sunflower plants carrying systemic infection are severely stunted and leaves are entirely chlorotic.
  • Affected plants bear abnormally thick, downward curled leaves showing prominent yellow and green mottling.
  • The stem becomes brittle. Small angular greenish yellow lesions may appear on leaves as a result of secondary infection.
  • Fungal growth is visible at lower surface.


Management
  • Seed treatment with Metalaxyl at the rate of 3 g per kg of seed has been found to give effective control.
  • Choice of planting sites and disposal of infected crop residues also give a fairly good control.




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Rust: Puccinia helianthi

Symptom
  • It is more prominent in the rabi season and in the kharif season the appearance is usually late.
  • This disease in conjunction with Alternaria blight of leaves may cause yield loss up to 40 per cent.
  • Uredo pustules appear first on the lower leaves. Uredo pustules appear on the younger leaves and later spread over the entire vegetative surface covering stems, petioles, floral bracts and petals.
  • Uredia often coalesce to cover large areas on the affected plant parts.

Management
  • Spray Mancozeb 1000 g/ha



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Alternaria Blight : Alternaria helianthi

Symptom
  • The disease is a destructive one, widely distributed wherever the crop is grown.
  • Severe reduction in seed and oil yield reported.
  • The most affected components are number of seeds per head and the seed yield per plant.
  • The disease also affects the quality of sunflower seeds by affecting germination and initial vigour of the seedlings.
  • The disease is characterised by the development of dark brown to black, circular to oval spots varying from 0.2 to 5 in diameter.
  • The spots are surrounded by necrotic chlorotic zone with grey white necrotic centre marked with concentric rings.
  • Spots first appear on lower leaves, later spread to middle and upper leaves.
  • At later stages, spots may be formed on petioles, stem and ray florets.

Management
  • Occurrence and severity of the disease depends on the season and planting dates.
  • Mid-September planting of sunflower remains free from the disease.
  • Foliar spray with 0.3 per cent Mancozeb four times at an interval of 10 days controls the disease.



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Charcoal Rot : Macrophomina phaseolina

Symptom
  • Charcoal rot is of economic importance particularly in the arid areas.
  • The most common symptom of the disease, under field conditions is the sudden wilting of plants, usually after pollination.
  • Early symptoms are not visible on infected plants, but they become weak, mature early and when dry, show a presence of black ashy discolouration of the stem.
  • Black microsclerotia are formed in huge number on the affected portion.
  • Sometimes the disease causes seedling blight, damping off, root rot or basal stem rot.

Management
  • Soil application of P. fluorescens or T. viride – 2.5 Kg / ha + 50 Kg of well decomposed FYM or sand at 30 days after sowing.
  • Spot drenching with Carbendazim @ 1 gm/ litre



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Sclerotium Wilt Or Rot : Sclerotium rolfsii

Symptom
  • Initial symptoms of the disease are noticed 40 days after sowing. Sickly appearance of plants can be noticed from a distance and a row effect can be observed in heavily infested soil. Later the entire plant withers and dies.
  • White cottony mycelium and mustard-seed-type sclerotial bodies are conspicuous on the affected stem near soil level.

Management
  • Collection and destruction of plant debris.
  • Seed treatment with Captan or Carboxin 3g/kg and drenching the base of the plant with Carbendazim 1g/lit.



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Rhizopus Head Rot : Rhizopus sp

Symptom
  • Initial symptom appears as brown irregular water soaked spots on the back of ripening head usually adjacent to flower stalk.
  • Spots gradually enlarge and become soft and pulpy and get covered with superficial white mycelium which later becomes black.
  • Some seeds of the rotted heads shed and those which remain in the head taste bitter.
  • Injury before flowering or during the early stage of head development is unlikely to favour infection even though the inoculum may be present.
  • Maximum rotting is noticed at the soft dough stage.
  • Seed development is severely impaired depending on the stage of maturation at the time of Rhizopus infection and rot development.

Management
  • To have effective control of the disease, simultaneous application of compatible insecticide and fungicide beginning with the completion of flowering stage is suggested.
  • Injury to the head should be avoided as far as practicable.
  • Spray Mancozeb @ 2g/lit in case of intermittent rainfall at the head stage.

Virus Diseases of Sunflower
  • Spray Mancozeb 1000g/ha in case of intermittent rainfall at the head stage, directing the spray to cover the capitulum.
  • Repeat fungicidal application after 10 days if humid weather continues



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Sunflower mosaic virus (SMV)

Symptom
  • Several kinds of symptoms have been described from India. Mosaic symptoms accompanied by ring spots or chlorotic spots which had a tendency to coalesce have been frequently reported.
  • Another mosaic virus described as mosaic and chlorotic rings that were more common on young leaves which make the plants stunted, producing malformed heads and shrivelled seeds.
  • Symptoms as small circular spots on leaves which coalesced to form typical mosaic pattern, cupping and malformation of leaves have also been reported.
  • Sunflower mosaic virus is reported to be mechanically sap transmitted and also by several aphid vectors.
  • The important vectors are Aphis gossypii, A.craccivora, A.malvae, Rhopalosiphum maidis in a non-persistant manner, both under laboratory and natural field conditions.
  • The host range of this virus ranged from narrow, infecting only the cultivars of sunflower to as many as more than 25 plant species belonging to different families.



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Tobacco streak virus

Symptom
  • This virus has been reported from Argentina.
  • It produces mosaic symptoms followed by necrosis and vein swelling severe necrosis and chlorosis on the leaves and curling of glumes are the additional symptoms.
  • It is transmitted through mechanical sap and also by dodder. Nicotiana clevelandi, N.rustica, Chenopodium amaranticolor, Gompherena globosa are the additional hosts of this virus.



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Yellow blotch disease

Symptom
  • Distinct bright yellow blotches occurred on leaves crinkling was absent. Also, short, irregular yellow vein bands appear in the beginning and later coaleasced to form "Y" or concentric rings with either yellow or a green centre.
  • Some yellow bands coalesced to form brilliant yellow blotches measuring 1-3 cm in diameter.
  • In mildly affected plants, only a yellow vein-net involving some or all of the leaf surface was observed.
  • Under field conditions, some plants show more severe symptoms after yellow blotch appearance.
  • The youngest leaves were twisted, reduced in size and often curled downwards.



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Leaf crinkle disease

Symptom
  • The symptoms of this disease always develops first as yellow blotch, but later leaf crinkling symptoms dominate.
  • The electron microscopic studies of the group of symptoms of this disease revealed the presence of spherical particles measuring 26.8+0.15 mm in diameter.

Management
  • Like in any other virus diseases of crop plants, there are no direct methods of controlling the viruses of sunflower.
  • Since the sunflower mosaic is transmitted both by mechanical means and also by aphid vectors in a non-persistant manner, it is very difficult to protect the plants from infection of the virus through this type of vectors.
  • However, the following methods helps much in reducing the incidence and further spread of the virus diseases in the field and thereby reducing the yield losses, have been suggested.
  • Following clean cultivation by removing the weeds both inside and neighboring plots which helps to destroy the virus source and avoid the primary inoculum to the crop.
  • Prophylactic sprays with suitable insecticides to control the insect vectors which come from outside the field and also harbouring inside the field, helps to avoid the primary sources and also further spread in the field.
  • Careful destruction of the infected plants as soon as they are noticed in the field will also help to avoid further spread of the viruses in the field by destroying the source of inoculum within the field.

Updated on April, 2014


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