Field Crops> Sunflower (Helianthus annuus L.)> Diseases

There are a number of diseases which are responsible for reduction in yield both quantitatively and qualitatively. Important diseases and their control measures are being given below.

Seed Rot

After sowing, some of the seeds rot because of the presence of moulds on their surface. To protect the seed from rot and also to get good stand in the field, seed should be treated with Apron at the rate of 6 g/kg of seed.

Charcoal Rot

This disease is caused by a fungus, Macrophomina phaseoli. This disease may occur to a consideiable extent in summer crop. The affected plants mature early and when dry show black ashy colour of the stem. Flower heads on the affected plants remain undersized.

Control Measures: (1) Use certified seed only.
(2) All infected plants should be removed and burnt.
(3) Follow 3-4 years crop rotation.

Alternaria Blight

This disease is caused by the fungus, Atternaria helianthi. This disease occurs in severe form during rainy season. There are dark brown to black round spots on the leaves which later become concentric.There is usually a narrow chlorotic zone around the spots. Under favourable conditions, the spots coalesce and cause blight of leaves. The dead leaves dry up and droop on the stem.

Control Measures: (1) Treat the seed with Apron at the rate of 6 g/kg of seed.
(2) Spray weekly 2.5 kg Mancozeb 75 WP dissolved in 1000 litres of water per hectare. First spray should be given as the disease starts appearing on the lower leaves. A total of four sprays are required
(3) Grow resistant/tolerant varieties like KBSH-1, APSH-11, MSFH-8 etc.

Sclerotium Wilt

This disease is caused by the fungus, Sclerotium rolfsii. Plants can be affected at any stage of the growth. The sickly appearance of the plants can be seen from a long distance. A whitish growth of the fungus along with mustard seed like bodies can be seen over the affected plants near the soil surface.

Control Measures: (1) Collect and burn the affected plants together with 15 cm of surrounding soil.
(2) Follow crop rotation.
(3) Keep the field free from weeds.

Sclerotinia Wilt and Rot

This disease is caused by the fungus, Sclerotinia sclerotiorium. This disease mostly appears in Rabi crop. The wilt symptoms of this are the same as of Sclerotium wilt except that the sclerotia which are noticed on the affected portion are black, large and irregular. Sometimes, instead of wilt, rotting of stem and head can be noticed. This can be recognised by shredding of the affected stem and head.

Control Measures: (1) Treat the seed with Apron at the rate of 6 g/kg of seed.
(2) Collect and burn the affected plants.
(3) Follow up crop rotation preferably with cereals.
(4) Keep the field free from weeds.