A fungal disease of sunflower caused by Phoma macdonaldii (Leptosphaeria lindquistii), affecting all vegetative organs and flower heads. It is characterized by the appearance of necrotic spots, which on stems take on a distinctive blue-black color with a metallic sheen.
In the reference
479
varieties
crop Sunflower,
where this is mentioned in the description.
The pathogen of the disease is the fungus Phoma macdonaldii, which also has an ascomycete stage of development, Leptosphaeria lindquistii. Symptoms appear on leaves at the 3–4 pair of true leaves stage as brown spots with a yellow margin, which spread to the stem through the petioles. At the points of petiole attachment, large dark brown or blue-black necroses occur, which can girdle the stem and lead to a loss of tissue integrity.
Infection of the flower heads manifests as the appearance of brown spots on their dorsal side, which leads to the formation of shriveled seeds or their complete underdevelopment. In sunflower breeding, there are no lines with complete genetic resistance to the pathogen, so work is carried out exclusively in the direction of selecting tolerant hybrids based on the evaluation of their phenotypic response under conditions of natural or artificial inoculation.
General information about the subject — on the page
Phoma rot.
Varieties of Sunflower mentioned in the description
Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.