As an annual weed species in the pigweed family, waterhemp is capable of producing more than one million seeds per plant, and, in recent years, has emerged as a major threat to soybean production. According to the Purdue University Extension, just a few untreated weeds in a field can lead to a major infestation within a couple of years.
A summer annual broadleaf weed with a germination period that lasts several months, waterhemp can grow in a variety of climates, as evidenced by its presence in 40 states. A distinguishing characteristic of waterhemp that sets it apart from similar species in the pigweed family is the lack of hair on its stems and leaves, giving the weed a bright, glossy appearance.
Various factors have led to the increase in waterhemp populations, such as the adoption of reduced tillage, changes in herbicide programs, and the reduction in the use of cultivation as a weed management tool, according to the Iowa State University Extension. Adding to the increase are warm air temperatures coupled with increased soil moisture, which create an extensive amount of waterhemp growth in a short period of time.
Due to a limited number of effective herbicides, particularly in soybeans, waterhemp is difficult to control compared to most weed species. In many states, waterhemp has shown an increased resistance to glyphosate, and has confirmed resistance to auxins (2,4-D), ALS, HPPD*, PPO and PSII inhibitors, leading to failure to control the weed in soybean production, according to Purdue University researchers.
To properly manage waterhemp, a combination of pre-emergence and post-emergence herbicides is recommended, along with the use of row cultivation, according to Iowa State University weed scientists.
For preplant or pre-emergence control of waterhemp, Syngenta offers BroadAxe® XC herbicide for broad-spectrum, long-lasting residual control. BroadAxe XC combines multiple modes of action to effectively control waterhemp and many other weeds.
To further control waterhemp populations, follow BroadAxe XC with Flexstar® GT 3.5 herbicide for a post-emergence over-the-top application in glyphosate-tolerant (GT) soybeans. Flexstar GT 3.5 consists of two leading active ingredients and two different modes of action, providing fast, effective control of more than 50 broadleaf weeds in soybeans, like waterhemp.
BroadAxe XC and Flexstar GT 3.5 enable you to target difficult-to-control weeds that have developed or are likely to develop resistance to glyphosate and/or ALS-inhibitors in GT soybeans, while maximizing yield and profit potential. These brands, when combined with cultural practices such as crop rotation and tillage, help you reduce the weed seed bank, maximize diversity and fight herbicide resistance.
For all of the latest soybean news, visit SyngentaUS.com/soybeans or contact Syngenta at 866-796-4368. Tap into agronomic insights on KnowMoreGrowMore.com to help maximize your fields’ potential. Join the conversation online – connect with us at Social.SyngentaUS.com.
*Resistance has only been confirmed in post-emergence applications.
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