The effect of mowing date on the development of common ragweed (Ambrosia artemisiifolia L.)

Common ragweed (Ambrosia artemisiifolia L.) is native to North America; it was introduced into Europe by contaminated agricultural goods from the end of the 19^th century. Since then due to its excellent ecological adaptability it has invaded whole Europe. Common ragweed is not only a noxious weed causing yield losses in agricultural crops; it invades disturbed urban areas and its highly allergenic pollen induces allergic rhinitis to sensitive people. In urban areas mowing is the most widely used mean of ragweed control.

Plants were mowed early (12 June) at BBCH 33 (3 visibly extended internode), late mowed plots were cut off on (25 July) .inflorescence visible BBCH 51 Mowing twice happened on 12 June and 25 July. At mean plant density of 91 plant/m² number of female flowers was 150/plant on an average, while that of the male inflorescences were 1676. Mowing treatments significantly decreased the above ground fresh biomass and plant height compared to the none-mowed control. The early mowing treatment did not decrease significantly the number of female flowers. Twice mowed and late mowed treatments significantly decreased the number of female flowers, that of the male inflorescences. Further studies are required to improve seed production decreasing effect of mowing treatments.