Virus infection in garlic considerably reduces yield and quality in Argentina. The production of virus free "seed" was attempted by means of thermotherapy and meristem tip culture. A hot water treatment was employed to determine the lethal temperature/time cobmination for clonal type (c.t.) Blanco cloves. It was established that 50-degrees-C x 20 min, 50-degrees-C x 15 min and 55-degrees-C x 5 min were the limit thermal/time combinations which garlic could withstand. Those treatments were employed followed by meristem tip culture, however, none of the successfully developed plants after culture (only 13 %) were virus-free. Hot air treatments in a growth chamber at 36-degrees-C lasting for 30, 40 and 60 days, and at 25-degrees - 32-degrees-C for 30 days in a greenhouse were tested on c.t. Blanco. Cloves kept at room temperature throughout the experiment were employed as controls. In the 25-degrees - 32-degrees-c treatment, 73 % of meristems produced plants and, of these, 33 % were virus free. After 30 and 40 days at 36-degrees-C, 62 % and 67 % of the meristems developed into plantlets, of which respectively 51 % and 50 % were virus-free. Very few meristems (10 %) developed into plants when cloves had been kept at 36-degrees-C for 60 days but the resulting plantlets were all virus free. Controls produced 78 % of plants, of which 14 % were virus free. Results of hot air treatments of 36-degrees-C for 40 days performed on c.t. Colorado, Rosado, Paraguayo, Espanol and Hilario Ascasubi were similar to those obtained with c.t. Blanco. In Espanol and Hilario Ascasubi, no virus-free plants were detected among control specimens (no thermotherapy treatment). The only virus (from up to 3 that infected the plants) that persisted in some plants after thermotherapy and meristem tip culture was garlic yellow streak.
