Safflower: Diseases and Symptoms

Alternaria blight

• It 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.

• The disease is externally and internally seed borne. The pathogen survives through spores (conidia) or mycelium in diseased plant debris or weed.

• Moist (more than 70% relative humidity) and warm weather (12-25 ºC) and intermittent rains favours disease development.

Cercospora leaf spot

• Safflower 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.

• The fungus survives in seed and affected plant debris and spreads through wind borne spores.

• Warm humid weather favours the disease development.

Powdery mildew

Disease symptoms

• The disease is characterized by whitish powdery growth on leaves
• Later the fungus spreads over the entire leaf. Leaves turn yellow and dry up

• The pathogen survives as oospores on the affected plant tissues and on weed hosts

• Cool (10-20ºC) and wet weather (90% RH) favours disease development

Head rot and wilt

• 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

• In 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.

• 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

• Round 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

• 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

• 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

• 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