Perennial Weed Populations After 14 Years of Variable Tillage and Cropping Practices

Abstract

Management of perennial weeds is a major concern in reduced-tillage cropping systems. Field research was conducted at Nashua, IA, from 1977 through 1990 to evaluate the long-term impacts of tillage and cropping patterns on perennial weed populations in corn and soybean production. Continuous corn and a corn/soybean rotation were conducted utilizing moldboard plow, chisel plow, ridge tillage, and no-tillage systems. The research area was free of established perennial weed species at the initiation of the experiment in 1977. Hemp dogbane was observed by 1980, with the greatest densities in no-tillage. By 1990, continuous corn had greater hemp dogbane densities with no-tillage than other tillage system by crop rotation treatments. American germander densities were not affected by tillage systems in 1980 and 1981, but by 1990, corn/soybean rotations had greater densities in moldboard plow than other tillage systems. Field bindweed developed primarily in the corn/soybean rotations with the greatest densities occurring in no-tillage. Greater and more diverse populations of perennial weeds developed in reduced-tillage systems than in the moldboard plow system. However, practices used to control annual weeds and environmental factors interacted with tillage to regulate perennial weed populations.

Which cropping systems to reconcile weed-related biodiversity and crop production in arable crops? An approach with simulation-based indicators

“…These field reports also pointed to the main short-coming of the simulation-based method, i.e., FlorSys only considers annual weed species. This is not a problem in tillagebased systems as shown by the evaluation (Colbach et al, 2015, submitted) but certainly leads to underestimating weed harmfulness in no-till systems which tend to favor perennials (Buhler et al, 1994;Tørresen et al, 2003;Norsworthy, 2008;Trichard et al, 2013), indicating that the low or no-till strategies identified here as optimal for reconciling production and biodiversity would only remain efficient if there were no risk perennials. Pending the development of a perennial weed dynamics model, an indicator of perennial weed spread depending on cultural practices could be developed from expert opinion.…”

Weed Problems, Ecology, and Management Options in Conservation Agriculture: Issues and Perspectives

“…Several studies have documented that NT increased the density of perennial weeds (Buhler et al, 1994;Bryson and Hanks, 2001;Torresen and Skuterud, 2002). In contrast, Derksen et al (1993) concluded from several experiments that an increased association of perennial and annual grasses did not generally occur.…”

“…Efficient weed management has been identified as a limiting factor in the adoption of CT systems (Buhler et al, 1994;Stevenson et al, 1998;Mas and Verdu, 2003), as under noninversion tillage systems weed seeds are not buried when soil is inverted by the plough (Morris et al, 2010). Other than weed menace, the problems associated with the maintenance of crop residues in the field; in countries where there are alternate uses for the crop residues is also a serious concern.…”

“…Buhler et al (1994) have noticed greater and more diverse populations of perennial weeds under RT systems in corn-soybean rotations. Buhler (1995) found that the densities of large-seeded dicot species often decreased under RT in corn-soybean rotation as minimizing soil disturbance affected the composition of weed communities (Zanin et al, 1997), e.g., small-seeded weeds, such as pigweeds, emerged only from shallow burial depths (0.5-2.5 cm) (Buhler et al, 1996;Ghorbani et al, 1999;Oryokot et al, 1997).…”

“…Literature worldwide has proved the dominance of grassy perennial weeds under RT (Froud-Williams et al, 1983a,b, 1984 as well as NT, as species shifts and adaptation might occur when an environment changes over time and the management of shift to perennials is a major concern. The perennial species varies from one cropping system to another, of which field bindweed in corn/soybean rotation (Buhler et al, 1994) is a classic example in the United States. Swanton et al (1993) opined that this shift may either represent long-term ecological succession or temporary fluctuations in species composition.…”