International Journal of Plant Protection

Kalamesh Basarigid , K. Karuna ¹, Y. G. Shadakshari ¹, K. S. Jagadish ¹, K. N. Geetha ¹

Affiliations
1 A.I.C.R.P. on Sunflower, Zonal Agricultural Research Station, University of Agricultural Sciences, Bengaluru Karnataka, IN

Abstract

Sunflower is an important oilseed crop of India. The crop is known to suffer from many diseases among which Alternaria leaf blight is one of the most important diseases. Alternaria helianthi was isolated from the leaf samples collected during Kharif. The toxin produced by Alternaria helianthi in potato dextrose broth was purified and based on its carbohydrate and protein content, the toxin was identified as glycoprotein. Toxin at 100 ppm concentration didn't affect seed germination while toxin concentration of 200 ppm to 3000 ppm affected seed germination. Minimum seed germination of 24.66 per cent was recorded when seeds were treated with toxin @ 3000 ppm. Minimum length of sunflower shoots (2.53 mm) and ischolar_main length (2.15 mm) was observed at 3000 ppm. Sunflower seedlings placed in 100 ppm toxin showed curling of leaves and wilting after 24 hr. whereas at 3000 ppm seedlings showed curling of leaves in 5 h and wilted within 12 hr. In detached leaf assay, 100 ppm toxin didn't produce any symptom. However, at concentrations of 500, 1000, 2000 and 3000 ppm, the toxin produced typical necrotic spots without yellow halo on sunflower leaves.

Keywords

Bioassay, Toxin, alternaria Helianthi, Leaf Blight, Sunflower

Full Text

     

Kalamesh Basarigid ¹, K. Karuna , K. S. Jagadish ¹, Y. G. Shadakshari ¹, K. N. Geetha ¹

Affiliations
1 Zonal Agricltural Research Station, University of Agricultural Sciences, Bengaluru Kanataka, IN

Abstract

Symptoms of Alternaria leaf spot/blight were observed in the form of small scattered brown spots on the leaf surface. Further, these spots covered larger leaf area with dark brown margin and yellow halo with indistinct zonations. Linear necrotic lesions were observed on the stem, petioles, capitulum, sepals, and petals at different stages of plant growth. Isolation of the fungus from the infected leaf sample collected from the field yielded Alternaria helianthi and pathogenicity was proved on KBSH 44 which expressed the symptoms in 8-9 days after inoculation under laboratory condition. The pathogenicity studies showed the external symptoms as small scattered brown spots on the leaf surface. Later, these spots increased in size covering larger area with dark brown margin and yellow halo with indistinct zonations. Linear necrotic lesions also appeared on stems, petioles and sepals. Cultural studies revealed that potato dextrose agar (82.80 mm) was the best followed by Sunflower leaf extract agar (71.54 mm) and Richard's agar (63.64 mm) for growth of fungus. Whereas, the growth of A. helianthi was not observed in water agar. In case of liquid media, potato dextrose broth yielded maximum dry mycelial weight (282.79 mg) followed by sunflower leaf extract broth (241.51 mg).

Keywords

Leaf Blight, Symptoms, Isolation, Pathogenecity, Culture Media

Full Text