ChileanJAR

In the case of flower rot of sunflower (Helianthus annus L.) caused by Sclerotinia sclerotiorum (Lib.) De Bary cv. Mayor, only a few sclerotia replace the seed while most of the sclerotia are formed beneath the seed in the parenchymatic tissues of the capitate inflorescence. Cross sections of the thin-walled parenchymatic cells of the testa and of the inner layers of the pericarp are infested with mycelial strands of S. sclerotiorum. Only in one occasion mycelium was observed to penetrate into the cotyledons. Howerer, in general, the cuticle and/ore the epidermis of the cotyledons appear to act as barrier against penetration by this fungus.
In the experiment with seed desinfectants, only a volatile, organic mercury fungicide (etil mercurio p-tolueno sulfanilida 7.7%) eliminated S. sclerotiorum completely in infested sunflower seed.