Elements of a technology of a quick test of sunflower plants susceptibility to Phoma rot infection at the first development stages

The research work was conducted in the laboratory of immunity of the V.S. Pustovoit All-Russian Research Institute of Oil Crops (VNIIMK), Krasnodar. The disease Phoma rot caused by the fungus Plenodomus lindquistii (Frezzi) Gruyter, Aveskamp & Verkley is widely spread in the many countries where sunflower is cultivated. Depending on the weather conditions, yield losses can reach 30– 70%. The pathogen inflicts the greatest harm to the host plant when the root system is damaged at the first stages of development, with direct contact of the root with the infectious matter of the fungus remaining in the infected plant residues in the soil. As a result of infection, seedlings die or the plant does not develop and does not enter the generative phase. The purpose of the research was to create elements of a quick test of sunflower plants susceptibility to Phoma rot infection at the first stages of crop development, to use this in sunflower 115 breeding for resistance to this disease. We tested three experimental doses of the infection level on sunflower variety VNIIMK 8883 and hybrids Mercury and Altair to create infected soil for artificial inoculation in special containers, where as a substrate for plants cultivation we used one-to-one weighted doses of river sand. We stated the dose of infection per a container should vary within 10–15 g at weighted dose of substrate (river sand) of 750 g. We developed 6-point scale to access visual symptoms of sunflower plant susceptibility to root system infecting with Phoma pathogen.