Calendral Appearance Of Major Diseases Of Sunflower In India

Sl.No.	Insect pests and diseases	Crop stage	Pest status
1.	Alternaria blight, Alternaria helianthi (Hasnsf) blight	Foliage	Severe
2.	Head rot, Rhizopus arrihizus Fisher	Capitulum	Severe
3.	Charcoal rot, Macrophomina phaseolina (Tassi) Goid	Root	Severe
4.	Root rot (Sclerotinia sclerotiorum (Lib) deBary	Root	Severe

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Downy Mildew (Plasmopara helianthi)

• The disease was unknown in India till 1984.
  
• In 1985, it has been reported to Occur in a serious form in Maharashtra.
• The causal fungus Plasmopara helianthi is considered to be of North American origin.
• It has been distributed rapidly by seed trade.
• Preliminary observations in Maharashtra indicate the possibility of large scale reduction in yield due to attack of this disease.

Symptoms

	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. On young seedlings under high humidity whitish growth of downy mildew may appear on the cotyledons. There is pronounced reduction of secondary rootlets Flower heads of the affected plants remain sterile and produce no seeds or only occasional. When older plants are infected, symptom expression may be delayed till head formation. Small angular greenish yellow lesions may appear on leaves as a result of secondary infection. Fungal growth is visible at lower surface. Such local infections are, however, considered to be of less importance.

Epidemiology

• Basal gall symptoms occur independently of systemic infection.
• The root infection may result in formation of galls on primary roots at the base of plants.
• Such plants are less vigorous and subject to lodging.
• Oospores of the fungus are observed in all affected tissues, but more oospores are found in affected roots than in any other organ.
• The pathogen survives through oospores in the residue of the preceding sunflower crop or through oospores on seeds in systemically infected plants.
• Seed transmission has been clearly demonstrated.
• Germinating oospores produce zoospores mostly under wet conditions.
• Zoospores cause infection.
• Seed borne infection usually results in low percentage of systemically infected plants.
• The outbreak of the disease in severe form is to a large extent due to soil borne inoculum.
• Rain in the early phases of growth arid age of seedlings at the time of infection are important factors in this context.
• Heavy soils with poor drainage are more conducive to infection.

Control

• Use of resistant varieties offers the best control.
• Besides 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 over the disease.

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Rust (Puccinia helianthi)

• Rust disease is prevalent throughout the sunflower growing areas in India.
• 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.

Epidemiology

Uredo pustules appear first on the lower leaves. They are small, circular 0.5 to 1 mm in diameter, powdery, orange to black. 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. Towards maturity, the uredo- sori are replaced by telia and the black rust stage appears. Puccinia helianthi is a macrocyclic, homothallic and autoecious rust producing all the stages of spore forms on a sunflower. It is restricted in its host range to annual and perennial Helianthus species. Puccinia helianthi mainly survives through teliospores on leaves left in the field. or on the soil surface.

• Possibility of survival of the fungus as teliospores or uredospores on the seed surface exists though as yet no positive information on seed transmission is available.
• Uredia, sporidia, pycnia, aecia may appear on volunteer seedlings among plant debris of the previ- ous year's crop. and survival of the pathogen through such volunteer plants is also a great possibility.
• Primary infection may result from sporidia, from germinating teliospores, aeciospores or from uredospores on volunteer plants at high altitudes and carried through air currents.
• Secondary infection occurs through repeatedly produced uredospores in a crop season.
• Day temperature of 25.5° to 30.5°C with relative humidity of 86 to 92 per cent enhances intensity of rust attack.
• Resistant varieties offer the best means of control.
• Tall and late forms are more resistant than dwarf and early ones.

Chemical control

• Two to three foliar sprays of dithiocarbamate fungicides like maneb, mancozeb or zineb at 0.2 to 0.3 per cent have been found effective in control of the disease.
• Sulphur fungicides like lime-sulphur, wettable sulphur (0.2 per cent), sulphur dust (15 kg per ha) also give good control.
• Nickel compounds, Bordeaux mixture, Miltox and systemic fungicides, benodanil and oxycarboxin have also been reported to be effective.

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Alternaria Blight (Alternaria helianthi)

• The disease is considered as a destructive one. It is widely distributed wherever the crop is grown.
• A reduction in seed and oil yield by 27 to 80 and 17 to 33 per cent respectively has been reported.
• A negative correlation has been established between an increase in disease intensity and yield components and oil content.
• The most affected components due to disease are number of seeds per head, followed by the seed yield per plant.
• The disease also affects the quality of sunflower seeds by affecting germination and initial vigour of the seedlings.

Symptoms

	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. 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. Epidemiology Pathogen is reported to survive on seed, host debris and weed host. Successive crops of sunflower may also help to multiply the pathogen. Hot weather and frequent rain during the milk and wax stages of development favour infection. The fungus is reported to produce a toxic metabolite, a phenolic substance in culture and leaf tissues.

Control

• Occurrence and severity of the disease depend on the season and planting dates.
• Mid-September planting of sunflower remains free from most of the major diseases including Alternaria infection which only shows traces 0.3 per cent mancozeb sprayed four times at an interval of seven to 10 days proved very effective in controlling the disease with increase in yield.
• Other fungicides, namely, zineb, ziram and captafol are also effective.
• Resistant sources identified are EC 132846, EC 132847, EC 132361 and EC 126184.

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Charcoal Rot (Macrophomina phaseolina)

• Charcoal rot is of economic importance particularly in the arid areas, where a reduction in seed weight of 30 to 46 per cent has been reported.
• The most common symptom of the disease, under field conditions is the sudden wilting of plants, usually after pollination.

Symptoms

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.

Epidemiology

• Pathogen survives as sclerotia in soil and crop residues. It is also reported to be seed borne in sunflower.
• The age of the plants appears to be a very important factor influencing the infection.
• Moisture stress and higher temperature favour development of the disease.

Control

• Practically no field control is available by using chemicals. Seed borne inoculum can, however, be minimised by treatment of seeds with thiram (3 to 4 g per kg seed).

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Powdery Mildew (Erysiphe cichoracearumf. sp. helianthi. , Erysiphe cichoracearum)

Symptoms

Powdery mildew on leaf surface

Symptoms of the disease appear as white to grey floury patches on the upper surfaces of older leaves, but still green. Occasionally the symptoms appear on stem and bracts. White to grey areas enlarge, coalesce and cover most plant parts. As the season advances cleistochecia become visible as black pinpoints over the white mildew areas. Pathogen survives through cleistothecia. The disease has not been observed to be of any economic importance. Sphaerothecli fuliginea This mildew appears as small, circular, whitish spots on both surfaces of the leaves. These enlarge to form larger spots covering the entire surface as dirty white growth. Symptoms start from lower' leaves and gradually younger leaves are attacked.

• With advance in age, mildew turns grey and numerous , minute black bodies of cleistothecia appear scattered over the lower surface of the leaves.
• Pathogen survives through cleistothecia.
• Development of cleistothecial stage of this fungus under Indian conditions appears to be governed by the presence or absence of the hyperparasite Cicinnobolus cesatii.

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Sclerotium Wilt / Rot (Sclerotium rolfsii)

Diseased plant

White cottony mycelium on stem base

Initial symptoms of the disease are noticed 40 days after sowing. Sickly appearance of plants can be rotted 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. About 10 to 11 per cent plants have been reported to be affected, amounting to 10 to 11 per cent loss in yield, if the sunflower crop is planted in July or August or in February or March in India.

Control

• The disease can be controlled by collection and destruction of plant debris.
• Seed treatment with captan or carboxin 3g/kg and drenching the base of the plant with cheshunt compound 3g per litre of water.

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Rhizopus Head Rot (Rhizopus sp)

Symptoms

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 due to the appearance of sporangia. In cases of severe infection, the rot spreads to flower stalk and the sunflower head drops off. Some seeds of the rotted heads shed and those which remain in the head taste bitter.

Favourable conditions

• The disease is of importance in wet weather and causes loss in yield.
• Injury to the flower head is necessary for infection.
• Injury before flowering or during the early stage of head development is unlikely to favour infection even though the inoculum may be present.
• Susceptibility of the flower head is increased as its age advances.
• 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.
• Larvae of Heliothis armigera have been reported to pre- dispose heads to infection.
• Spread of the disease is positively correlated with birds visiting the beads in search of seeds.

Control

• 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.

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Virus Diseases of Sunflower

• Several virus and virus like diseases have been reported by various workers on sunflower, both in India and abroad.
• Sunflower mosaic, chlorotic mosaic, yellow ring mosaic, yellow mosaic, yellow spot, chlorotic leaf/mosaic, greening, cucumber mosaic, curl mosaic and Mycoplasm like organisms (strain of tomato big bud, aster yellows and phyllody) have been reported.

Sunflower mosaic virus (SMV)

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 coaleasced 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. The dilution end point of different strains of this virus ranged between 1:1000 and 1:80000, thermal inactivation point ranged between 65 and 750C and the longevity in vitro ranged up to 4-5 days at room temperature.

• The serological studies revealed that the virus strains belong to the cucumber mosaic virus group by reacting positively, but the electron miscroscopic studies failed to reveal the presence of virus particles both in purified sap, dip preparation and also by ultrathin section of the infected leaf samples, as reported by several workers.

Aphid transmitted virus

• This virus has been reported from Cambridge. The chief symptoms produced are chlorosis and thickening of lower leaves.
• The interveinal areas of these leaves become bright yellow near the tip and margins, many irregular necrotic patches develop later on and these symptoms are reported to be similar to the sugarbeet yellowing virus.
• This virus is transmitted by an aphid vector, Myzus persicae.

Yellow ring mosaic virus

• This virus has been reported from India. It produces mosaic and yellow spot symptoms.
• Severe mosaic accompanied by stunting and malformation of young leaves in the form of yellow rings has also been reported.
• This virus is transmitted both by mechanical sap and also by leaf and cleft grafting and has an additional host, Chenopodium amaranticolor.

Tobacco streak virus

• This virus has been reported from Argentina.
• It produces mosaic symptoms follwed 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.
• The dilution end point of the virus ranged between 1:1000 and 1:10,000 thermal inactivation point ranged between 53 and 600C and the longevity in vitro ranged up to 48 hours at room temperature.
• The electron microscopic studies revealed the presence of isometric particles measuring 30mm in size.

Yellow blotch disease

• 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.

Leaf crinkle disease

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

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Management Of Virus Diseases

• 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 neighbouring 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.

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Mycoplasma Like Organisms

• Faster yellows causes chlorosis in sunflower has been reported from California and was reported to be transmitted by a leaf hopper, Macrosteles fascifrons.
• The brief symptoms of phyllody of sunflower are plant remaining stunted and leaves shows the presence of many zonal necrotic areas.
• Such plants produces abnormal heads and floral parts were transformed into green leaf like structures.
• The flower head may be transformed into twisted elongated stalks.
• Further witches broom symptoms can also be seen.From India, the symptoms of phyllody described as production of small chlorotic leaves.
• Internodes were reduced and plant become stunted. Such plants remain green for longer time.
• The capitulum instead of producing normal ray and disk florets, showed wedge shaped sectors with hypertrophied flowers.
• The ovary, calyx, corolla, anther tubes and branches of stylets show green colorued, short rudimentary leaves.
• It has been reported to be transmitted by leaf hopper vector, Orocious albicinctus, both under laboratyory and in field conditions.

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Integrated Disease Management In Sunflower

Introduction

Diseases and causes

• A large array of phathogenic fungi in or on the seed are assoicated with sunflower which induce pre and post-emergence mortalities in field.
• Several pathogens viz., alternaria, Fusarium, Macrophomina and plasmopara are seed transmitted and can cause loss of seedlings.
• The developing plants of sunflower are prone to infection by alternaria blight downy mildew, rust and a large array of foliage damaging pathogens like phoma exiqua, A.alternata, A.zinniae, Cercospora helianthi, septoria helianthi, etc.
• Amongst stem and root diseases, charcoal rot or dry root rot (Macrophomina phaseolina) and stem or collar rot (sclerotium rolfsii) are damaging in patches in many areas.
• Head rot (Rhizopus sp.) has been commonly observed in Punjab, Haryana and U.P. on spring sown crop.
• Currently sunflower is known to be infected by bacterial with (Pseudomonas solanacezarum), cladosporium blight, phoma blight, fusarium wilt and a mosaic virus.
• These are sporadic at present but could be serious in future.
• Although exact estimates of yield losses due to diseases of sunflower have not been investigated, it has been reported that diseases account to the tune of 30% reduction during Kharif and about 5-10% during post-Kharif seasons.

Guidelines

• IDM as practiced in the developed countries is a sophisticated technology achieving computerised on line service.
• Practical IDM methods have been suggested for less developed countries or for traditional agro-ecosystem.
• It is based on efficacy, ecology and economics employing routine and supervisory practices with minimum use of agro-chemicals being backed by epidemiology and management components.
• Education and extension should also form an integral part of IDM.
• The current IDM, therefore, could be based on the following principles of management
• Choosing any resistant or tolerant hybrid cultivar for cultivation.
• Compulsory seed treatment with available effective fungicides prior to sowing.
• Deep ploughing, followed by double harrowing and removal of volunteer plants as land preparation components.
• Addition of FYM prior to addition of recommended inorganic fertilizers.
• Compulsory crop rotation of at least three four years.
• In rainfed situation with known history of disease outbreak, intercropping with suitable crop.
• Since there are no known threshold limits of diseases, actual survey and monitoring of diseases by way of diagnostic symptoms and signs.
• Rainfall prediction through national satellite network during kharif, and then link the spraying technology with rain pattern.
• Alternaria epidemic is ensured when sunflower head stage is cought in heavy rain.
• Two sprays of mancozeb at 0.255 with appropriate stickers before head emergence can prevent damage by the disease.
• Crop rotation if coupled with green manuring legume crop can be of great use in reducing soil or stubble inhabiting spore forms.
• During post-rainy seasons optimum use of irrigation water, avoidance of water stagnation, avoidance of direct contact of water with stem, wider spacings between plants and planting on ridges has been found useful in curtailing disease outbreaks.
• There are some areas where research gaps exists e.g., resistance to Alternaria, development of biocontrol system, forecasting models for disease epidemics, role of rhizobacteria and VAM etc.
• Integrated disease management is possible provided the components of management are suitably amended in IPM or in the total crop management system.

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Legislative Approach

• Failure to check the downy mildew pathogen of sunflower from introduction into India is a glaring example of how relaxed quarantines could be harmful.
• Since the Not so aggressive race 1 has entered the country, it is still important to have a strict vigilance on the entry of downy mildew for virulent races through quarantine means .
• Presently downy mildew is restircted to Central and South India, domestic quarantine measures can be adopted to prevent it from spreading to North India where it could pose a threat during rabi and spring seasons.
• Regulatory measures are, thus, an important component of management of diseases as it has been known to prevent entry of downy mildew pathogen into Australia.

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Host Resistance Approach

• The best option for disease management is host resistance.
• In sunflower development programme in India, it has become amply clear that incorporation of resistance of downy mildew and rust diseases into high yielding hybrids and cultivars is possible.
• Several sources of resistance to rust are known and the R1 and R2 genes have been widely utilised in development of rust resistant hybrids.
• The rust resistance has been originally derived from accession 953-88 (sunrise x Texas wild annual 0 carrying R2 gene).
• The resistance in the selection 953 102-1-122 from another accession is governed by R1 gene and has been incorporated in the two hybrids, advent and admiral.
• In India, several sources of resistance have been reported.
• These include 24 RHA lines 12 CMS, 20 hybrids, 5 inberds, 4 wild species and 86 open pollinated populations.
• A number of germplasm accessions have shown highly resistant reaction in the national screening projects.
• The widely used cultivars morden and EC 68414 are susceptible but majority of the hybrids released for cultivation are tolerant or highly resistant.
• The race flora of the rust pathogen has not been understood clearly in India.
• It is, therefore, necessary to understand the genetics of the pathogen, monitor the races and programme the resistance breeding accordingly.
• Downy mildew resistance breeding is well advanced in the USA, Russia and Europen countries.
• Thus, when the disease was first detected in India.
• A well suited three-tier screening system for downy mildew was developed and several sources of resistance to race 1 has been identified.
• New downy mildew resistant restorers; MRHA-1 and MRHA-2 were developed from segregating populations of HYSUN-33.
• Based on the breeding programme, two downy mildew resistant hybrids for endemic pocket of Maharashtra have been released.
• These hybrids LSH-1, CMS 338 Ax MRHA- 2.) and LSHO3 (CMS-207A x MRHA-1) have very good yield potential but posed some problem of seed production which are currently being refined.

Disease	Yield losses(%)
Alternaria Blight	90	10-30
Downy mildew	80	2-25
Rust	35	1-10
Soil borne disease	30	1-10
Seed borne disease	23	2-7

• Nine number of high yielding hybrids such as KBSH- 1, ICI-302, NSH-22, PKVSH-38, ITC-601, MSFH-17, SPIC-105, Jwalamukhi, NARF-114, KBSH-31 etc., have fairly high degree of resistance mainly because the majority of them have either one or both the parental lines derived from resistant sources.
• Therefore, management of downy mildew through resistance should not pose a problem in India provided monitoring of races is continued.
• Alternaria blight is by far the most serious and damaging disease during rainy season.
• The outbreak of the disease is closely linked with rainfall and it is also difficult to control when weather conditions are favourable.
• Attempts have been made to identify sources of resistance to the disease.
• However, high degree of resistance is not found in the available germplasm lines.
• Field tolerance has been observed in few lines and fortunately the hybrids often exhibited greater tolerance than cultivars.
• There are no specific efforts as yet in the country to evolve cultivars resistant to head rot, stem rot, dry root rot or other disease problems.
• Technique of screening for disease resistance are to be evolved before a breeding suitable practices that suppresses the growth pathogens but selectively favour growth of the host crop.

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Cultural Approach

	Ploughing, harrowing, weeding, planting time, Organic amendments, fertiliser, use, intercropping, planting method, micronutrient balance, water use, etc., have impact on disease development of sunflower. The oldest known cultural practice of crop is basically a classical approach for reduction of diseases. A six year rotation in sunflower is found useful in the control of downy mildew in Russia and European countries. Crop rotation also reduces alternaria blight, rust and soil borne diseases. It is very clear that outbreak of sunflower downy mildew is ensured by water stagnation, deep sowing, continuous sunflower growing and those practices that delay emergence of seedling. The influence of several practices on different diseases has been examined at number of locations in India. It has been observed that early planting of sunflower during kharif reduces damage by Alternaria.

• Also intercropping, spacing, manuring has great effect on diseases which could be exploited fully for the advantage of disease management summarizes the beneficial effects of some major cultural practices on sunflower diseases.
• It is, therefore, suggested that emphasis on crop rotation, intercropping, timely planting, proper water use and field populations of sunflower be given a priority in management of disease.

Influence of cultural practices on sunflower disease

Practice	Disease	Severity%	Yield(Kg/ha)
Time of planting
a.) Onset of monsoon	Blight	30.8	842
b.)Three weeks delayed	Blight	60.0	796
Intercropping
a.) Groundnut+Sunfnlower	Blight	19.5	1640
b.) Sole sunflower	Blight	42.2	930
Manuring
a.)FYM or green manuring	Stem rot	4.5	1200
b.) No manuring	Stem rot	21.3	930
Irrigation
a.) One irrigation	Downy mildew	3to 6	1640
b.) Six irrigation	Downy Mildew	50 to60	701
Spacing
a.) 45 cm x 15 cm	Downy Mildew	18.6	-
b.)60 cm x 30 cm	Downy Mildew	4.5	-

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Biological Approach

The soil borne pathogens particularly sclerotium, Macrophomina and fusarium can be efficiently reduced by the biocontrol agents trichoderma and gliocladium. There is a great potential for application through seed as these systems have been widely used in other crops.

• A concentrated effort is also necessary to examine the organic management of diseases through vermicuture biofertilizer, plant porducts like neem extract and neem oil and commercially available natural products.
• The role of vasicular arbascular mycorrhiza (VAM) has also not been investigated which could be a part of integrated management.

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Chemical Approach

• The use of fungicides in management of sunflower diseases has been extensively documented in experimental trials.
• However, the utilisation of this strategy is restricted mainly because of cost, avaialbility and suitable time of application
• Chemical control in rainfed situation need to be restricted to seed treatment.
• This is an assured, safe and cost effective strategy and demonstrated throughout the country.
• A large number of pathogens in or on the seed can be effectively controlled by a range of available fungicides such as, PCNB, captan, Carbendazim, carboxin, thiram etc.,
• In case of irrigated crop management, limited use of spray fungicides particularly mancozeb (0.25%) or carboxin (0.05%) plus mancozeb (0.2%) effectively reduces alternaria blight and rust.
• However, the benefits of seed treatment have been found to be nearly equal to three sprays particularly in resistant hybrids.

Efficacy of seed dressing on control of seed and seedling diseases

Treatment.	Emergence	Yield (Kg/ha)
		Protected	Unprotected
PCNB (0.2 %)	85.2	1413	1116
Captan (0.2%)	84.7	1428	1116
Carbendazim (0.2%)	87.1	2180	1580
Carboxin (0.2%)	84.5	1972	1580
Thiram (0.2%)	85.0	2067	1580

• Mayee observed that the response of chemical control of rust in terms of yield of seed is higher in susceptible cultivars like Modern and EC 68414 but the chemical control response was negligible in resistant hybrids like MSFH-8, VSF-1 and VSF-2.
• However, since the losses in oil yield are not proportional to the degree of severity of rust in sunflower cultivars, the resistant hybrids exhibited high response to oil increase by chemical control of the disease.
• Thus, chemical sprays could be used efficiently provided the loss potential, cost benefit and some knowledge of likely outbreak of disease are known.
• There is no work on the epidemiology and forecasting of Alternaria blight, rust and downy mildew which will go a long way in optimising the chemical control strategy for sunflower diseases.

Influence of chemical management on diseases and yield of sunflower

Treatment	Cultivar	Downy mildew (%)	Blight (%)	Yield (Kg/ha)	Oil (%)
Control	Morden	20	28	626	38.7
	LSH - 12	6	25	908	36.8
SeedTreatment	Morden	3	24	760	38.7
	LSH - 12	3	23	1059	37.0
Three sprays	Morden	17	16	725	40.0
	LSH - 12	8	11	972	38.0

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