The 2001–2002 season was particularly severe for argentine potato crops in regards to late blight infections, especially those located in the southeast region of the Buenos Aires province, the country’s main growing area. A conjunction of several factors may explain the situation: late planting due to excessive rains during the spring; low or nil application of fungicides due to the economic crisis; and excessive rains at the end of the growing period.

As previously reported by INTA Balcarce, in vitro resistance to metalaxyl has been found in 100 % of the isolates from different parts of the country. Therefore, the few growers that relied upon this product may have had greater difficulties in controlling blight. The use of chemicals with translaminar action gave some relief, when complemented with contact fungicides — although it was difficult to get any kind of agrochemical in the market. As a result of this shortage some growers went back to old formulas such as the application of the Bordeaux broth.

A renewed interest in resistant varieties has been manifested and Pampeana INTA was requested from INTA as an alternative to the highly susceptible Spunta and Kennebec. DSS (Decision Support Systems) are on trial by private companies and also by INTA, as they may give more rationality to the use of fungicides. A project of integrated and organic potato production is being launched through a coordinated action between growers, INTA, universities and municipalities as an alternative to the traditional cropping system, which is highly dependant on the use of agrochemicals.

Submitted by Marcelo Huarte, Coordinator Potato Group and National Potato Subprogram, INTA, Balcarce, Argentina, email: marcelohuarte(at)yahoo.com