Original articleEfficient reduction of biomass, seed and season long pollen production of common ragweed (Ambrosia artemisiifolia L.)

- In urban area the most widely used method for ragweed control was improved.
- Ideal timing and mowing height significantly reduced seed and pollen production in Ambrosia artemisiifoila.
- The assessment method of pollen production is unique, reproducible and based on season long collection of pollen grains.
- Optimal mowing dates are: first mowing before flowering of the terminal racemes (BBCH 59), second when re-sprouting terminal racemes reach (BBCH 59).
- 1-3 cm is the optimum cutting height.

Ragweed (Ambrosia artemisiifolia L.) is a noxious plant that not only is a troublesome agronomic weed that causes economic damage to agricultural crops but also − and even more importantly − causes severe health problems due to its severe allergenicity. The pollen of invasive ragweed has become a major allergenic risk factor in urban areas in newly occupied regions. Many urban areas prohibit herbicide application; thus, mowing is the most widely used control measure. Counting pollen is labour intensive; therefore, pollen production data are mainly based on estimations. Field experiments were conducted to determine the effects of different mowing scenarios, plant density and cutting height on the biomass, pollen production and seed production of common ragweed plants. Ragweed plants were mown twice: just before the flowering of terminal racemes (BBCH 59) and when the flowers of the re-sprouting lateral shoots reached BBCH 59. A 1- to 3-cm cutting height produced the greatest pollen reduction compared to that of intact control plants (94%) based on a season-long pollen collection. The number of female flowers also significantly decreased (97%). Compared to the control, the onset of pollen discharge was delayed by 5 weeks and the length of the pollen discharge period decreased from 9 to 4 weeks. The season-long unique and reproducible pollen production data can be integrated with airborne pollen modelling and population management strategies.

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