Volunteer sunflower (Helianthus annuus L.) is a major problem in crop rotations which include sunflower. Sunflower (Helianthus annuus) seeds germinate in late spring and plants flower and set seeds in the same growing season. The seeds are eaten by birds and small mammals. It is a sturdy annual dicotyledon, growing 1–3 m tall. At all stages the plant is very large, with sturdy stems and large bright, yellow flowers.
The seeds of sunflower can persist in the soil for up to five years and have the ability to germinate at a considerable depth and over a long period. Although it may occur as a volunteer in the two years following a crop, it rarely persists for longer.
The growth of these volunteers was more vigorous where the crop was less competitive, especially on headlands and in gateways.
It is easily cleaned out from most other crop seeds.
For advice on herbicides, please speak with your agronomist or adviser.
Source: https://ahdb.org.uk/
