Macrophomina phaseolina (Tassi) Goid. - Charcoal Rot of Sunflower.
Systematic position.Fungi, Ascomycota, Ascomycetes, Macrophomina.
Synonyms:Sclerotium bataticola Taubenh.; Rizoctonia bataticola (Taubenh.). ( http://www.SpeciesFungorum.org ).
Morphology and biology.The causative agent of Charcoal Rot of Sunflower is the fungus Macrophomina Phaseolina, developing only during the anamorphous stage in its life cycle. Morphological structures of the pathogen are vegetative mycelium and sclerotia. It also has a stage of sterile mycelium (Rhizoctonia bataticola) in its developmental cycle. The first visible symptoms of the disease are shown in the beginning of flowering as darkening of sunflower stalks near roots. Later it causes full withering of plants. Affected stalks become light gray. At strong disease severity, the surface tissue macerates. Inside the affected tissue of stalks, particularly in the central cylinder, numerous black small sclerotia are formed, varying in size from 50 to 200 mkm. They are formed less intensively inside the affected roots. Destruction of the affected stalk tissue results in full death of the plants. The disease can attack the head, later affecting seeds. Sources of the infection are the affected residues, microslerotia in soil, and infected seeds. The pathogen can also attack other cultures.
Distribution.In the former USSR, the Charcoal Rot of Sunflower is registered in Russia (Northern Caucasus, Central Black Soil Zone), Ukraine and Moldova.
Ecology.The causative agent affects sunflower in dry regions, more intensively in some places in dry years. Optimal temperature for growth and development for the pathogen are 30°C.
Economic significance.Yield loss of sunflower infected with the disease can reach 25%. Control measures include crop rotation, use of less susceptible varieties and hybrids, and pre-sowing treatment of seeds.
Reference citations:Acimovic' M. 1962. Sclerotium bataticola Taub., kao uzrocnik uvelosti suncokreta u Vojvodini. Zasita bilja, p.69-70 (in Serbian).
Kukin V.F. 1982. Diseases of sunflower and control measures against them. Moscow: Kolos, 80 p. (in Russian).
Maric A., Camprag D. & Masirevic S. 1987. Sunflower diseases and pests and their control. Belgrade: Nolit, 379 p. (in Serbian).
Mihaljcenic' M. 1978. Choosing a suitable technique for screening sunflower for resistance to charcoal rot in climatic condition of Yugoslavia. Proc. of 11th Inter. Sunfl. Conf. Minneapolis, p.258-264.
Yakutkin V.I. 2001. Diseases of sunflower in Russia and their control. Zashchita i karantin rastenii 10: 26-29 (in Russian).