S. Masheva, N. Valchev, V. Yankova

Abstract. The experiment was conducted in 2007 and 2008 with leek variety Starozagorski 72. Single treatment with biostimulator Aveikan® was performed (2,5 L/ha) in phase 6-7 leaf of the crop and threefold in seedlings phase, one week after transplanting and 20 days after second treatment. Aveikan® stimulates the growth and reproductive manifestations of the leek. The greatest increase was observed in the average weight. It is 19,64 % higher than the control in single treatment and in threefold – 33,93 %.The average stem height is 7,88 % higher in threefold treatment. The effect of Aveikan® is strongly expressed on the reproductive manifestations in leek. The yield of seeds in the treated plants is 37,50% higher than in the untreated plants. The treatment with Aveikan® has no significant effect on the degree of infestation by rust (Puccinia porry) and on the density of tobacco thrips (Thrips tabaci).