EN
Susceptibility of triticale to infection by powdery mildew (Blumeria graminis) in field and greenhouse conditions was studied. Each year in these sites were examined 55–60 objects. Observations on triticale crop were carried out for four years. The resistance to disease was evaluated using the 9-grade scoring system (9 to 1), where 9 – absence of symptoms and 1 – very strong infection. Every year the mean infection degree was significantly higher in greenhouse than in the field. A close correlation was found between infestation severity in the field and greenhouse after heading stage. Greenhouse observations on triticale supplement or replace field scoring especially in non favourable seasons. Observations of triticale infestation by powdery mildew confirmed break down of resistance in short time.