Abstract
Corn- and soybean-dominated cropping systems create and maintain a favorable environment for summer annual weeds whose emergence and growth phenology are similar to these annual summer crops. Cropping system diversification can be an effective approach for controlling noxious weeds without increasing reliance on chemical herbicides. Diversification may be especially important for managing waterhemp, a dioecious, summer annual weed that is becoming increasingly prevalent in the US Corn Belt due to its life history characteristics and herbicide resistance profile. Compared to corn and soybean, alfalfa and oat emerge and establish earlier and are thus more competitive with warm-season weeds like waterhemp. Knowledge of vegetative and reproductive characteristics in a range of crop environments can be valuable for planning weed management strategies. However, most of the relevant characteristics for a population dynamics model were available in corn and soybean monocultures. We examined the relationship between waterhemp's aboveground mass and fecundity under four crop species' presence within three crop rotation systems: a 2-year sequence of corn and soybean; a 3-year sequence of corn, soybean, and oat intercropped with red clover; and a 4-year sequence of corn, soybean, oat intercropped with alfalfa, and alfalfa. All the rotation systems were treated with conventional or reduced rates of herbicides. We established eighteen linear equations to predict waterhemp's fecundity from dried aboveground mass in each crop and associated crop management program since measuring the latter allows for quicker estimation of fecundity compared to counting seeds on each individual plant. Rotation system and crop phase within rotation system had significant effects on all the response variables but weed control regime on some. The sex ratios at maturity were slightly female-biased in oat and alfalfa. Mature waterhemp plants were larger in corn and soybean than in oat and alfalfa. Oat and alfalfa were planted earlier than corn and soybean and successfully competed for resources against waterhemp despite the absence of herbicide or interrow cultivation. Frequent hay cuts in alfalfa served as physical weed control and contributed to suppressing waterhemp and other weeds substantially.
Highlights
Cropping system diversification can contribute to the effective suppression of noxious weeds such as velvetleaf (Abutilon theophrasti Medik.) (Westerman et al, 2005), giant foxtail (Setaria faberi Herrm.) (Liebman et al, 2014), giant ragweed (Ambrosia trifida L.) (Liebman and Nichols, 2020), and other species while complementing the effects of herbicides and physical weed control practices (Davis et al, 2012; Weisberger et al, 2019)
The present study focuses on fecundity and other relevant individual- and populationlevel reproductive and vegetative characteristics of waterhemp [Amaranthus tuberculatus (Moq.) J
In the conventional weed management regime, herbicide was broadcast on the whole area that was planted to corn, whereas in the low herbicide regime, herbicide was applied in 38-cm bands over corn rows, and interrow areas were cultivated
Summary
Cropping system diversification can contribute to the effective suppression of noxious weeds such as velvetleaf (Abutilon theophrasti Medik.) (Westerman et al, 2005), giant foxtail (Setaria faberi Herrm.) (Liebman et al, 2014), giant ragweed (Ambrosia trifida L.) (Liebman and Nichols, 2020), and other species while complementing the effects of herbicides and physical weed control practices (Davis et al, 2012; Weisberger et al, 2019). Much of the effectiveness of diversified cropping systems for weed suppression can be attributed to differences among crop species in their phenologies and the management techniques applied to them. Differences in crop phenology and diverse management tactics can lead to a net loss in weed seed population density in the soil seed bank (Liebman and Gallandt, 1997; MacLaren et al, 2020) resulting from reductions in weed fecundity and increased consumption of weed seeds by granivores. D. Sauer] in three rainfed cropping systems differing in crop species richness and management practices
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
