The center of origin of peanut is located in South America, specifically in southeastern Bolivia and northwestern Argentina, where its parental species are found in wild habits. Even though Argentina is only the seventh largest producer of peanut in the world (2% of global production), it is the leading exporter of edible grain and crushed (e.g., flour, butter, and oil) peanut products worldwide. Peanut production was moved to more southern areas of Cordoba in the early 1990s to avoid the consequences of production issues in the northern region. During this migration process, a new disease emerged in commercial plots: peanut smut caused by Thecaphora frezii. Peanut smut was first detected in the northern peanut producing areas in Córdoba Province, and then established on the central region where the main grain processing industries are located. Currently, the prevalence is 100% in Argentinian peanut area. This finding showed evidence that pathogens could also migrate along with peanut production activities and contaminate soil of new production areas.

Red stripe is a bacterial disease of sugarcane causing important economic losses in Argentina that affects 30 % of the milling stems and consequently the juice quality. In this study, sugarcane leaves exhibiting red stripe symptoms were sampled in the 2008-09 growing season from 13 different sugarcane producing areas of Tucumán and Salta (northwest of Argentina). To achieve the identification and characterization of the causal agent of red stripe, bacterial isolation was performed. Species-specific PCR using Oaf1/Oar1 primers allowed the amplification of a fragment of 550 bp from approximately 50 % of the isolates; 16S rDNA sequences analysis displayed a similarity greater than 99 % with Acidovorax avenae subsp. avenae. By means of RAPD-PCR the presence of at least four different biotypes among the analyzed isolates was detected. Results of pathogenicity test allowed us to confirm A. avenae subsp. avenae as the pathogenic agent for red stripe. This study constitutes the first report on the identification and molecular characterization of this plant pathogen from the Argentina sugarcane production areas. The genetic diversity observed among A. avenae is an important factor to be considered to improve an accurate diagnosis and/or the selection of sugarcane tolerant clones.

Thecaphora frezii was first reported in 1962 in wild peanut from Aquidauana, Mato Grosso do Sul, Brazil. In Argentina, it was first detected in 1995 in commercial crops from the central-northern area of Córdoba province. The fungus can survive in the soil as teliospores. When peanut gynophore penetrates the soil, their exudates disrupt telial dormancy; T. frezii penetrates and colonizes the tissues and replaces the cells with teliospores. Since its first report, peanut smut prevalence has gradually increased in peanut areas to reach a 100% in 2012. Currently, it is the most important peanut disease in Argentina, not only for its destructive power on crop but also for its quick spread throughout the growing region of Córdoba and the lack of effective tools for its management. It is important for additional research to find effective agronomical practice that reaches high control efficiencies. The collaboration of all those involved in Argentinian peanut production systems is necessary for the management of peanut smut to be successful.

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