THE DISCOVERY OF THE RHIZOMANIA RESISTANCE TRAITS IN SUGARBEET.

Authors: DE BIAGGI, M - CROP RES.INST.ITALY; ERICHSEN, A - HOLLY SUGAR (RETIRED); Lewellen, Robert; BIANCARDI, E - CROP RES.INST.ITALY

Submitted to: International Institute For Beet Research Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 2/26/2003
Publication Date: 8/20/2003
Citation: DE BIAGGI, M., ERICHSEN, A.W., LEWELLEN, R.T., BIANCARDI, E. THE DISCOVERY OF THE RHIZOMANIA RESISTANCE TRAITS IN SUGARBEET. INTERNATIONAL INSTITUTE FOR BEET RESEARCH PROCEEDINGS. 2003. p. 131-147.

Interpretive Summary: Previously recognized as soil sickness or confused with other sugar beet diseases, the symptoms of rhizomania (in its current meaning) were known in several European countries well before the Second World War. Its rapid spreading was noticed in Italy after 1946, and few years later sporadic symptoms of the disease wee observed over 10,000 hectares in areas of intense cultivations. Without knowing the true pathogenic factor, some prophylactic measures were adopted: (1) avoid excess water; (2) avoid spreading of contamination trough machinery and tare soil; (3) early harvesting in diseased fields; (4) sowing Italian variety with high sugar content. The last advice was established after a number of field trials that included different commercial varieties. Later became evident that the best entries carried the quantitative resistance named "Alba type". Around 1965, the pathologists involved in such researches could establish that the rhizomania was caused by an atypical fungus-virus symbiosis. With this discovery, the disease was correctly explained, and the word rhizomania became used over many important sugar beet production countries. In the 1970's, both the rapid diffusion of the disease and the worsening of the damages on sugar yield pushed many research institutes and seed companies to find more efficient control measures. After years of searching, two monogenetic traits now known as "Rizor type" and "Holly type" were identified and commercially exploited in Italy (1983) and in U.S.A. (1986), respectively. For both countries, the full and particular background of the discovery of the different rhizomania resistances is given by the breeders involved.

Technical Abstract: Previously recognized as soil sickness or confused with other sugar beet diseases, the symptoms of rhizomania (in its current meaning) were known in several European countries well before the Second World War. Its rapid spreading was noticed in Italy after 1946, and few years later sporadic symptoms of the disease wee observed over 10,000 hectares in areas of intense cultivations. Without knowing the true pathogenic factor, some prophylactic measures were adopted: (1) avoid excess water; (2) avoid spreading of contamination trough machinery and tare soil; (3) early harvesting in diseased fields; (4) sowing Italian variety with high sugar content. The last advice was established after a number of field trials that included different commercial varieties. Later became evident that the best entries carried the quantitative resistance named "Alba type". Around 1965, the pathologists involved in such researches could establish that the rhizomania was caused by an atypical fungus-virus symbiosis. With this discovery, the disease was correctly explained, and the word rhizomania became used over many important sugar beet production countries. In the 1970's, both the rapid diffusion of the disease and the worsening of the damages on sugar yield pushed many research institutes and seed companies to find more efficient control measures. After years of searching, two monogenetic traits now known as "Rizor type" and "Holly type" were identified and commercially exploited in Italy (1983) and in U.S.A. (1986), respectively. For both countries, the full and particular background of the discovery of the different rhizomania resistances is given by the breeders involved.