WILDTYPE SUNFLOWER CLONES - SOURCE FOR RESISTANCE AGAINST SCLEROTINIA-SCLEROTIORUM (LIB) DE-BARY STEM INFECTION

Sunflower (Helianthus annuus L.) cultivars show a wide range of suscep tibility to the pathogen Sclerotinia sclerotiorum (Lib.) de Bary resul ting in high yield losses. Sufficient levels of resistance have not be en found in cultivated but in wild sunflowers. The objective of this w ork was to screen in vitro vegetatively propagated clones from eight w ild sunflower species for resistance to the pathogen. The plants were subjected to a mycelium stem and a mycelial outgrowth test. One resist ant species H. maximiliani Schrader and two moderately resistant speci es H. nuttallii T&G and H. giganteus L. were identified. The resistant clones will be further propagated to act as source for protoplasts, p roviding disease resistance to H. annuus cultivars via somatic hybridi zation.