Article 20
1. In accordance with the procedure referred to in Article 25(2), the Commission may prohibit, in whole or in part, the marketing of seed potatoes harvested in a particular area of the Community if the progeny of officially drawn samples of basic seed potatoes or certified seed potatoes harvested in that particular area and grown in one or more Community test fields has for three successive years fallen appreciably below the minimum conditions laid down in Annex I(1)(c), (2)(c), (3) and (4). Satisfaction of the other minimum conditions laid down in Annex I may also be checked during the comparative tests. 2. Any measures taken under paragraph 1 shall be withdrawn by the Commission as soon as it has been established with adequate certainty that the basic seed potatoes and certified seed potatoes harvested in the particular area of the Community concerned will in future satisfy the minimum conditions referred to in paragraph 1. 3. The necessary arrangements shall be made, in accordance with the procedure referred to in Article 25(2), for the comparative tests to be carried out. Seed potatoes harvested in third countries may be included in the comparative tests.