Canada thistle phenology in broadbean canopy

Abstract

Soine of the developmental stages of Canada thistle - <i>Cirsium arvense</i> (L.) Scop. (I. emergence and early growth, II. shooting, II. budding, IV. flowering, V. fructification, VI. shedding of fruits) on the background of development stages of broad-bean, weeded by herbicides and without that weed-killing substances, were presented in the paper. Phenological observations were carried out on the plants growing on alluvial soil developed from light loam in Zakrz6w near Tarnobrzeg. It was proved that phenological development of Canada thistle, during broad-bean vegetation, depended on course of weather conditions and method of crop care. Emergence of the weed occurred earlier than broad-bean plants during warm and rather dry seasons. In every vegetation period, emergence and early vegetation stage (to 4 leaves seedling) of Canada thistle lasted about 3 months, until broad-bean got full pod setting. During wet and cold season (in 2001) the weed emerged also early under herbicide (Afalon 1,5 kg ha<sup>-1</sup>) condition. Until to broad-bean harvest, Canada thistle attained the finish developmental stages, that means fruiting and fruit shedding. Herbicide treatment delayed the last two stages and limited fruit shedding by plants of <i>Cirsium arvense</i>.