A Method for Evaluation of Sunflower Resistance to Diaporthe/Phomopsis helianthi Munt. Cvet. et al.

V. ENCHEVA and I. KIRYAKOV
Dobroudja Agricultural Institute BG-9520 General Toshevo, Bulgaria

Abstract

ENCHEVA, V. and I. KIRYAKOV, 2002. A method for evaluation of sunflower resistance to Diaporthe/Phomopsis helianthi Munt. Cvet. et al. Bulg. J. Agric. Sci., 8: 219–222

The use of a fast and easy to apply method for inoculation is of primary importance in breeding for resistance of sunflower cultivars and hybrids. A fast and easy to apply method for testing the breeding materials resistance to Diaporthe/Phomopsis helianthi is suggested to include in the breeding program. Sunflower plants at buttoning stage were inoculated with the help of the straw method. Results were read 10 days after inoculation according to a five degree scale: 0 – no symptoms or traces of pathogen invasion; 1 – spot covering the leaf petiole up to the stem; 2 – spots up to 5 cm long; 3 – spots covering the next internodule; 4 – stem breaking at the place of inoculation.
A high positive correlation (r = 0.86; P = 0.033) was established between the results obtained from the application of the straw test and the natural infection. The results obtained allow as to recommend the straw method for preliminary testing of sunflower germplasm for resistance to Ph. helianthi.

Key words: Diaporthe/Phomopsis helianthi, sunflower, method for inoculation