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Wild Sunflower (Helianthus annuus)

Crop Impacts: cultivated fields

Wild Sunflower 1

About Wild Sunflower:

No one thinks that a sunflower could be a weed but low and behold it is. Wild Sunflowers are an annual plant that tends to grow wild in Canada, western USA and the northern parts of Mexico. Wild Sunflowers are spread and or planted by the carrying of seeds by humans and birds. They are very aggressive wild flowers that compete against row crops for sunlight, water and nutrients.

Family: Asteraceae Family

Wild Sunflower 2 Wild Sunflower 3

Wild Sunflower Scouting and Prevention:

Wild Sunflowers have a large flower head sitting at about 5 inches across with yellow petals and a red-brown central disk. The leaves alternate along the stem, and are rough, green, egg-shaped, or heart-shaped, have a scratchy texture and can grow up to 1 ft long. Under ideal circumstances the thick green stem can grow up to 9 ft tall, but typically is around 4 to 6 ft in height.

Common locations

  • - Cultivated fields
  • - Dry soil

Prevention

Prevention of Wild Sunflowers is definitely difficult due to the fact that most areas are contaminated by birds. That being said, make sure when you are seeding a new area you are doing so with certified weed-free seeds. If there is an infested area on your property, be sure to drive around, instead of through it. Finally, make sure to give all equipment that has been in infested fields a good clean, to make sure no seeds are transferred.

Wild Sunflower Control:

Cultural Control

Cultivation and hoeing are important cultural control methods for the control of sunflowers. Due to the fact that sunflowers have quite a strong root system, using implements to remove them is crucial. It is important when tilling fields that you do so when the sunflowers have two or more leaves. Harrowing may need to be done numerous times if the weed keeps emerging but only if field conditions are stable. If there is any weed missed by early tillage they can be controlled by cultivation between crop rows.

Chemical Control

Trying to control older and larger plants is much more difficult and time consuming, therefore timely application is critical. Herbicides will be ineffective if applied when the plant is under stress. The herbicides will have more effect right before or right after rain due to the fact that the roots of the plants are taking in water at the time, which in turn means they will be taking in the herbicides as well.

Latin / Alternative Wild Sunflower names:

  • - Helianthus annuus
  • - Common sunflower
  • - Annual sunflower

Additional Wild Sunflower Resources

https://www.fireflyforest.com/flowers/1209/helianthus-annuus-common-sunflower/

http://www.johnson-county.com/dept_sec_roads.aspx?id=1745

https://plants.usda.gov/plantguide/pdf/cs_hean3.pdf

https://appliedweeds.cfans.umn.edu/weedbull/Sunflower%202008.pdf