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Safflower: Diseases and Symptoms

Alternaria blight

Disease symptoms
  • blight imgIt is the most destructive disease.
  • Dark necrotic lesions 2-5 mm in diameter are formed first on hypocotyls and cotyledons.
  • In mature plants, small brown to dark brown concentric spots of 1-2 mm appear on leaves.
  • Symptoms also appear on stem and severely infected plant gets blighted.
  • Brown discolouration appears on the stem, dark brown spots with concentric rings up to 1 cm in diameter appear on the leaves which later develop into large lesions.
  • Seeds also may be affected. Dark sunken lesions are produced on the testa. It may rot and damping off of seedlings occur.
Survival and spread
  • The disease is externally and internally seed borne. The pathogen survives through spores (conidia) or mycelium in diseased plant debris or weed.
Favourable conditions
  • Moist (more than 70% relative humidity) and warm weather (12-25 ºC) and intermittent rains favours disease development.

Cercospora leaf spot

Disease symptoms
  • Leaf spot imgSafflower plants few weeks after planting or at flowering stage are commonly attacked.
  • Circular to irregular brown sunken spots of 3-10 mm diameter are formed on leaves.
  • Spots are surrounded by yellow halos.
  • Symptoms first appear on lower leaves and spread to upper leaves.
  • Stems and nodes may also be affected.
  • In severe infections bracts are also affected with reddish brown spots.
  • Affected flower buds turn brown and die.
Survival and spread
  • The fungus survives in seed and affected plant debris and spreads through wind borne spores.
Favourable conditions
  • Warm humid weather favours the disease development.

Powdery mildew

Disease symptoms

Mildew img

  • The disease is characterized by whitish powdery growth on leaves
  • Later the fungus spreads over the entire leaf. Leaves turn yellow and dry up
Survival and spread
  • The pathogen survives as oospores on the affected plant tissues and on weed hosts
Favourable conditions
  • Cool (10-20ºC) and wet weather (90% RH) favours disease development

Head rot and wilt

Disease symptoms
  • Plants become yellowish, turn brown and ultimately die
  • Large black sclerotia of the fungus are formed on the crown inside the stem, floral heads and adjoining roots
  • Shredding of the stem takes place

Mosaic

Disease symptoms
  • Mosaic imgIn CMV infected safflower plants young leaves show irregular yellow or light patches alternating with normal green areas.
  • Leaves may become blistered and distorted and infected plants are stunted.
  • In few plants primary leaves are produced, forming a rosette of leaves exhibiting mosaic mottling and from the centre of this, the axis bearing secondary leaves are produced.
Transmission and favourable conditions
  • The disease is transmitted in semi persistent manner by aphid Aphis gossypii.
  • Aphids are more active in warm summer conditions and increased their population as well as spread the viruses more.

Ramularia leaf spot

Disease symptoms
  • Leaf spotRound and irregular spots of 100 mm or more in diameter occur on both sides of leaves
  • Whitish dense mass of conidia remain at the center which reflects light, dry spots are brown in color.

Rust

Disease symptoms
  • Seedling infection causes twisting towards one side
  • Chesnut brown postules are formed on hypocotyl leading to collapse of seedling
  • On older plants girdling and hypertrophy of the stem base may occur
  • Small powdery chesnut brown postules of 1-2 mm in size develop on leaf surface which later turn black.

Wilt

Disease symptoms
  • Yellowing of leaves on one side of plant starts particularly from lower leaves followed by wilting the progresses upwards
  • Lesion at soil line is first symptom noticed which extends inside and affects the vascular system
  • Plant starts to wilt, drooping more often
  • Infected heads have aborted seed.

Root rot

Disease symptoms
  • Dark cortical lesions occur slightly below or at the soil level on the stem, which later extend upwards
  • Lesions frequently girdle the stem
  • Root development is reduced and finally seedlings die

 

IPM for Safflower

To know the IPM practices for Safflower, click here.

Source: NIPHM and Directorate of Plant Protection, Quarantine & Storage



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