Integrated Pest Management

Alternaria blight

Causal Organism

Alternaria helianthi, A. alternata, A. zinniae,

Damage

• Symptoms appear on leaves, petioles, stem, sepals and petals.

• Symptoms appear as  dark brown irregular leaf spots with very dark border and grey centre.

• 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.

• In later stages the leaf lesions may coalesce causing the leaf to wither.

• The disease affect the quality of seeds by reducing the germination percentage.

• The infection of the disease causes losses up to an extent of 10 - 30%.

Survival & Favourable Conditions

• Pathogen 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.

• Disease development is favoured by 25-27^o C temperatures with at least 12 hours of wet foliage.

Cultural Control

• Soil solarization.
• Deep summer ploughing.
• Proper spacing
• Clean cultivation and field sanitation.
• Use of resistant or tolerant variety like B.S.H.1 .
• Application of well rotten manures.
• Practicing crop rotation.
• Planting on mid-September.

Mechanical Control

• Remove and destroy the diseased plants

Chemical Control

• Spray 2 or 3 zineb or mancozeb 2 g or carbendazim 1 g/litre of water at 10 days interval starting with first spray as soon as the disease appear or 35 days after sowing.

Rust

Causal Organism

Puccinia helianthi

Damage

• Small reddish brown spots appear on the lower leaves and they slowly spread on all the leaves and green parts of the head.
• The leaves may turn yellow
• The disease may cause reduction in yield up to an extent of 1 - 10%.
• The disease is favoured by wet weather conditions.

Survival & Favourable Conditions

• Survival of the fungus as teliospores or uredospores on the seed surface exists.
• Day temperature of 25.5° to 30.5°C with relative humidity of 86 to 92 per cent enhances intensity of rust attack.

Cultural Control

• Use of tolerant and resistant varieties
• Crop rotation should be followed.
• Previous crop remains should be destroyed.
• Crop sanitation practices should be practiced.

Mechanical Control

• Removal of crop resolves and reduces the disease severity

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 Jike lime-sulphur, wettable sulphur (0.2 percent), sulphur dust (15 kg per ha) also give good control.
• Nickel compounds, Bordeaux mixture, Miltox and systemic fungici- des, benodanil and oxycarboxin have also been reported to be effective.

Head rot

Causal Organism

Rhizopus arrhizus

Damage

• This is a serious disease of sunflower.

• Fluffy fungal growth is seen on the back side of  the head which spreads to entire head region due to which the whole head rots.

• In severe cases, the seeds are transformed into a black powdery mass.

Survival & Favourable Conditions

• The disease is of importance in wet weather and causes loss in yield.
• Injury to the flower head is necessary for infection.
• Susceptibility of the flower head is increased as its age advances.
• 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.

Cultural Control

• Use of resistant varieties if available.
• Deep summer ploughing.
• Clean cultivation and field sanitation.

Chemical Control

• Two sprays of Dithane M-45 at head formation stage.

Charcoal rot

Causal Organism

Macrophomina phaseolina

Damage

• The disease is caused due to prevailing dry and moisture stress conditions.

• 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.

Survival & Favourable Conditions

• 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.

Cultural Control

• Closer planting of the seedling should be avoided.
• Optimum nutrition should be provided to maintain the plant vigour.

• Whenever the soil becomes dry and the soil temperature rises then irrigation should be provided.

• In endemic areas long crop rotation should be followed.

Biological Control

• Seed treatment with Trichoderma viride formulation at 4 g/kg seed.

Downy mildew

Causal Organism

Plasmopara halstedii, P. helianthi

Damage

• The disease affect on root, basal, stem, leaf & seed.
• The symptoms are damping-off, systemic infection, local lesion, basal rot or stem gall.

• In systemic infection, plants are severely stunted, chlorosis causes abnormally thick, downward curled leaves and whitish downy growth develop on lower surface of the leaves.

• The flower heads are remain sterile and erect.

• Local foliar lesion symptoms are characterized by small angular greenish yellow spots on leaves.

• Infected plants exhibit discoloured, scurfy roots having gall on primary root.

• Affected plants dry and get away by wind.

Survival & Favourable Conditions

• Survives in seed, soil borne through oospores and secondary through wind-borne.
• Rain during seedling growth favours disease.

Cultural Control

• Use of resistant varieties l
• Deep summer ploughing.
• Clean cultivation and field sanitation.
• Early sowing and shallow planting (up to 3 cm).
• Avoid excessive irrigation.
• Prevent water stagnation.
• Follow crop rotation practice is endemic areas.
• Removal of infected plants.

Chemical Control

• Treat the seeds with metalaxyl at 5g/kg of seed.
• Application of Aprom 35 SP is found to reduce the disease incidence.

Sclerotical wilt/ Collar rot

Causal Organism

Sclerotium rolfsii

Damage

• Initial symptoms of the disease appear 40 days sowing.
• The infected plants can be identified by their sickly appearance.
• Plants dry up due the the disease infestation.
• The lower portion of stem is covered with white or brownish white fungal colonies.
• In extreme cases the plants wilts and dies.

Survival & Favourable Conditions

• It infection occurs in the crop in the month of July and August.
• The fungus survives as sclerotina in soil and plant debris.

Cultural Control

• Deep summer ploughing.
• Complete field and crop sanitation.
• Use of resistant or tolerant varieties.

Mechanical Control

• Collect and destroy plant debris.

Biological Control

• Apply Trichoderma spp., on seed and soil to reduce sclerotinia wilt.

• Apply and incorporate fungus Coniothyrium minitans before sowing as it invades and destroy the pathogen in the soil.

• Seed treatment with Psuedomonas fluorescens or P. putida strains protect sunflower from sclerotinia infection during seedling stage.

Chemical Control

• Seed treatment with captan or thiram at the rate of 3 g/kg of seed.
• Drenching the base of the plant with chestnut compound 3 g per litre of water.
• Seed treatment with carbendazim at 0.2% followed by the addition of Trichoderma harzianum T 10 g/kg soil and spraying carbendazim at 0.2 % to 15 days old seedling.

Powdery mildew

Causal Organism

Erysiphe cichoracearum

Damage

• The disease produces white powdery growth on the leaves.

• White to grey mildew appears on the upper surface of older leaves.
• As plant matures black pin head sized are visible in white mildew areas.
• The affected leaves more luster, curl, become chlorotic and die.

Survival & Favourable Conditions

• Survives in seed and soil borne through microsclerotia.
• The disease is more under dry condition to the end of the winter months.

Cultural Control

• Complete field and crop sanitation.
• Early varieties should be preferred.

Mechanical Control

• Removal of infected plant debris.

Chemical Control

• Application of sulphur dust at 25-30kg/ha or calixin 1 ml/litre is found effective in reducing the  disease incidences.

Mosaic

Causal Organism

TMV

Damage

• The infected plants show irregular yellow or light green patches alternating with normal green areas.

• Small chlorotic circular spots develop on leaves.

• Cupping and malformation of leaves, poorly developed root and reduction of pollen fertility are other symptoms.

Survival & Favourable Conditions

• The virus is transmitted through sap and seed and white flies.
• The virus survives in Amaranthus.

Cultural Control

• Roughing of infected plant.

Chemical Control

• Spray triazophos 1 ml or monocrotophos 1.5 ml per litre of water.